Tag: bacteria

ESRF X-rays capture vitamin B12 sensing light

ESRF X-rays capture vitamin B12 sensing light

Scientists led by the Institut de Biologie Structurale have combined advanced X-ray methods to unveil how a photoreceptor regulates carotenoid production in bacteria, including experiments at the ESRF. The results are out in Nature.

CarH is a photoreceptor which senses light through a vitamin B12 derivative and regulates carotenoid expression through direct interaction with genes. Bacteria use this remarkable machinery to regulate gene expression and produce carotenoid to protect themselves from photo-damage upon sun exposure. What scientists had never seen before was how tiny photoinduced changes at the vitamin B12 level, propagate into large-scale structural changes triggering a biological response. Now, an international collaboration has managed to film this process in unprecedented detail, with key experiments carried out at the ESRF and at XFELs.

CarH’s role has been clear since around 2015. In the dark, the protein binds to DNA and blocks the production of carotenoids. When light is present, CarH releases the DNA, allowing the cell to produce carotenoids that help defend against light-induced damage.

Previous crystal structures revealed the start and end points of this process. But the crucial missing piece was the journey in between — from the short-lived structural changes that occur immediately after light hits the vitamin B12 molecule to the large-scale conformational changes involving the whole protein structure and its interaction with DNA.

Read more on the ESRF website

Image credit: CEA and Maria Davila Miliani

Contribution of the HERMES beamline to the study of “Tubenets”

Contribution of the HERMES beamline to the study of “Tubenets”

Network-like structures built by bacteria inside insect cells to feed more efficiently

The cereal weevil, one of the world’s main crop pests, harbors symbiotic bacteria that live inside its cells. Scientists from INRAE and INSA Lyon, in collaboration with experts from the SOLEIL Synchrotron and Claude Bernard University in France, as well as the Max Planck Institute and EMBL in Germany, have discovered that these bacteria build complex, network-shaped membrane structures. These structures increase their surface area for exchange with the host cell, allowing the bacteria to absorb an essential nutrient: sugar.


This is the first time that bacterial structures of this scale have been observed. The SOLEIL’s HERMES beamline contributed to this discovery.

The cereal weevil is one of the major pests affecting cereals such as wheat, rice, and maize, both in the field and in storage. It feeds directly on the grains, but it is not alone: it hosts symbiotic bacteria that live inside its cells. These bacteria, named Sodalis pierantonius, reside in large numbers within specialized insect cells. They provide the weevil with essential nutrients that are absent from its cereal-based diet. This is a mutually beneficial relationship: the bacteria use the sugars produced during the digestion of grains and, in return, supply the insect with essential nutrients such as vitamins and certain amino acids.

While scientists have long understood the importance of this exchange, its exact mechanisms remained unknown. To investigate, the researchers used electron microscopy with an advanced sample preparation method that preserves membranes more effectively. For the first time, the team observed original tubular patterns forming complex membrane structures built by the bacteria. To study the architecture and composition of these structures, the scientists developed new 3D microscopy and analytical methods using the SOLEIL Synchrotron particle accelerator.

Read more on the SOLEIL website

Image: Scale 200 nm. Transmission electron microscopy image showing intracellular symbiotic bacteria from the cereal weevil Sitophilus oryzae. The bacteria form a three-dimensional network of tubular structures, called tubenets. These structures enhance host–bacterium nutritional exchanges, allowing efficient transfer of sugars from the host’s diet to the symbiotic bacteria. In purple, an example of a bacterium and its tubenets can be seen within the cytoplasm of the host cell.

Understanding bacteria’s role in transforming steroids to pharmaceuticals

Understanding bacteria’s role in transforming steroids to pharmaceuticals

Identifying 3D structure of enzymes by University of Guelph researchers key first step in harnessing alterations for disease treatments.

For decades, pharmaceutical companies have been using bacteria found in soil and water to chemically convert steroids into effective treatments for human diseases. One example is cortisol, which is used to treat asthma and skin rashes. But how bacteria convert steroids is not fully understood.

Now a research team from the University of Guelph has taken a significant step forward in answering that question. Using the Canadian Light Source (CLS) at the University of Saskatchewan, Dr. Stephen Seah and colleagues have determined the 3D structures of steroid-transforming enzymes from Proteobacteria (also called Pseudomonadota), a large, diverse family of gram-negative bacteria named after Proteus – the shape-shifting Greek sea god.Video: Understanding bacteria’s role in transforming steroids to pharmaceuticals

Studying the 3D structure of these enzymes, which Seah says would be impossible without the ultrabright X-ray source of the CLS, is key to understanding how this Proteobacteria chemically transforms steroids – such as bile acids – which are typically resistant to being changed.

Seah and his colleagues found that the bacteria have evolved to transform steroids as a means to obtain carbon and energy for their own growth. However, he says, these transformations can be harnessed to chemically alter steroids into compounds that we can use for disease treatments; a discovery that will help advance future pharmaceutical development.

“If we understand the process, we can manipulate other bacteria to produce novel compounds that may have medicinal properties,” says Seah. “I think my work helps fill in this gap of knowledge.” The team’s research findings were published recently in both the Journal of Biological Chemistry and Biochemistry.

This new research, says Seah, also opens the door to exploring the potential of other enzymes in bacteria to change the chemical structure of steroids. “In other words, one could create steroids with diverse chemical structures using the many steroid-modifying enzymes that bacteria produced to alter naturally occurring steroids,” he says. “Some of these modified steroids may have therapeutic properties.”

Read more on the CLS website

Image: Protein structure

Credit: CLS

Scientists visualise crucial step in protein production in bacteria

Scientists visualise crucial step in protein production in bacteria

Researchers have visualized for the first time how mRNA is delivered to the ribosome to begin production of proteins. They solved 9 of the structures using the ESRF’s cryo-EM. The results are published in Science.

Our DNA holds the instructions for making proteins, which are essential for the body to function. To use these instructions, a molecular machine called RNA polymerase (RNAP) copies the relevant section of DNA into a short-lived copy called messenger RNA (mRNA). This mRNA carries the instructions to another molecular machine, the ribosome. In bacteria, these two steps happen at the same time, allowing RNAP and the ribosome to cooperate and regulate each other.

A team led by Albert Weixlbaumer at the  Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC) in Strasbourg, France, wanted to know how bacterial ribosomes are recruited to mRNAs, while they are still transcribed by RNAP. Using cryo-electron microscopy (cryo-EM), they studied complexes where an mRNA emerging from RNA polymerase (RNAP) was bound to the ribosome’s small subunit.

The team used cryo-EM at the ESRF and at IGBMC to visualize the ribosome-mRNA assemblies at molecular resolution. This enabled them to observe the process in great detail. The cryo-EM experiments at the ESRF provided the structure of 9 of the complexes studied. “Access to high-end cryo-EM instruments is absolutely essential and represents the culmination of our work. It is a real pleasure to work with the scientists at the ESRF, we always feel they are very dedicated to the projects they support and the data quality and amount of date we obtain could not be better”, explains Albert Weixlbaumer, leader of the team and researcher at the IGBMC.

Complementary single-molecule fluorescence co-localization experiments carried out in the lab of Nils Walter (University of Michigan, USA) and in vivo crosslinking followed by mass spectrometry carried out in the lab of Juri Rappsilber (Technical University Berlin, Germany) suggest RNAP and the ribosome cooperate to facilitate recruitment of the small ribosomal subunit to the mRNA.

Intricate machines

“Our research reveals how these molecules work like intricate machines. I am always amazed that it is possible to reconstitute such an intricate and biologically fundamental process in a tube in the laboratory,” says Michael Webster, now a group leader at the John Innes Centre in the UK and one of the lead authors of the study which was published in Science.

“It is particularly exciting to have the opportunity to use powerful imaging techniques to answer questions that researchers have been interested in for a long time,” he adds.

Read more on ESRF website

Toxic behaviour: why do tuberculosis bacteria poison themselves?

Toxic behaviour: why do tuberculosis bacteria poison themselves?

Tuberculosis bacteria halt their growth with self-toxins that could inspire novel therapeutics

Stealthy bacteria slow down their division when they invade the body to avoid drawing the immune system’s attention. Mycobacterium tuberculosis, the world’s leading bacterial infectious killer, takes a seemingly counterintuitive approach to that end. M. tuberculosis expresses self-toxins that damage its DNA and shut down growth as well as antitoxins to later help recuperate and resume proliferation. By studying these toxin-antitoxin pairs, Durham University microbiologist Professor Tim Blower aims to find ways to mimic the self-toxins with new therapeutics

By conducting X-ray crystallography at Diamond’s I04 beamline, Blower and his colleagues uncovered the structure of toxin-antitoxin complexes, providing insight into how they regulate DNA damaging activity. The findings reveal that the protein pair potentially form two types of complexes. A grouping of two toxins and four antitoxins dominated at body temperature, whereas an equal pairing of two and two were more common in colder conditions, which may reflect how the proteins come together when bacteria live in the environment. These findings change our perspective on how the toxins and antitoxins operate, bringing researchers closer to designing new drugs against a pandemic microbe that continuously evolves resistance to existing antibiotics. 

Each year, Mycobacterium tuberculosis leads approximately 10 million people to endure a bloody cough, exhaustion, and fever, and it causes over one million deaths. Doctors typically prescribe patients a course of four to six antibiotics to clear the infection, but the bacteria evolve mechanisms to resist the effects of the drugs. As many as 2.5 percent of tuberculosis patients carry variants of the bacteria resistant to the four most common first-line antibiotics, and that proportion is expected to climb if researchers don’t develop other therapeutics that could kill resistant strains.    

Poison control

Blower and the team from Durham University and Newcastle University study mechanisms the bacteria use to limit their own growth in pursuit of inspiration for new drug candidates. Specifically, they focus on an enzyme that controls DNA organisation in the cell and a pair of toxins and antitoxins that regulate this enzyme’s function. 

Bacteria and eukaryotes (for instance, humans), organise DNA in the cell differently. Eukaryotic DNA is tightly packaged in the nucleus by histone proteins that wind it up into compact chromosomes. Bacteria, on the other hand, lack histones and rely on DNA to undergo a process called supercoiling. Like how a wound-up rubber band contracts into a small volume, bacterial DNA winds up into a condensed coil to save space. However, supercoiled DNA needs constant maintenance, which involves occasional unwinding and rewinding of the molecules. To this end, an essential enzyme called DNA gyrase cuts the DNA, allows it to untwist, and glues the cut ends back together again, so they can coil again. 

Repairing the DNA breaks is essential to the bacteria’s survival because it avoids the build-up of harmful DNA damage and mutations, but sometimes M. tuberculosis interferes with the process. It achieves this using a toxin-antitoxin system that inhibits DNA gyrase. Scientists are still uncertain about the biological role of the toxin, Blower said, but one hypothesis is that by partially shutting down bacterial growth, it prevents antibiotics that target growth machinery from working. Another is that the toxin helps quiescent bacteria evade immune detection as slow-growing microbes tend to slip under the radar. The antitoxin relieves the bacteria, allowing those that survived the accumulation of DNA breaks to seal them back together and resume growth when conditions in the body become favourable. 

Researchers developing new therapeutics are drawn to these systems. Suggesting scientists could develop copycat drugs, Professor Blower said: 

If these toxins are so effective at killing, then we should take advice from nature and work out how they work.

Read more on Diamond website

New research on gut bacteria could lead to helpful new probiotics

New research on gut bacteria could lead to helpful new probiotics

There are trillions of bacteria in the human gut microbiome. When we eat fruits and vegetables, some of these bacteria break down the dietary fiber and provide us with metabolites, small molecules our body can use for energy or cell repair.

Researchers from the University of British Columbia (UBC) used the Canadian Light Source (CLS) at the University of Saskatchewan to study a particular bacterium commonly found in the gut of people who eat a plant-rich diet.

The specifics of how bacteria break down our food is still a “black box,” according to Dr. Harry Brumer, the UBC professor who led this research. “Our team is trying to determine what molecular machinery the bacteria have that give them the unique ability to break down dietary fiber,” he said.

Using ultrabright synchrotron X-rays at the CLS and the Stanford Synchrotron Radiation Lightsource in California, Brumer and colleagues determined the three-dimensional structure and function of the proteins and enzymes this bacterium uses to break down food, and the details of that process.

“The CLS made it possible for us to study these mechanics on the atomic level,” said Brumer. “It’s really cool to understand how gut bacteria perform those complex processes and contribute to our health.” The team published their findings in the Journal of Biological Chemistry.

Read more on CLS website

Towards prevention of diabetes linked substance produced by human gut microbiota 

Towards prevention of diabetes linked substance produced by human gut microbiota 

The team at the Novo Nordisk Foundation funded life science beamline MicroMAX welcomed the first users in December 2023. In the experiment the users investigated an enzyme that may be found in some bacteria of human gut microbiota and may have a role in the development of diabetes and other diseases.

An enzyme called urocanate reductase may be present in the bacteria that are found in the human gut. The enzyme breaks down urocanic acid, a natural constituent of skin and other tissues of the body, into the metabolite imidazole propionate. The metabolite has been linked to diabetes and other diseases.

The user team from Lund University used MicroMAX to investigate the molecular structure of the enzyme.

“A possible therapeutic strategy is to inhibit the enzyme and prevent the imidazole propionate production. The high-resolution atomic structure is needed to design inhibitor molecules that could occupy the active site of the enzyme,” says Raminta Venskutonyte, one of the researchers who conducted the study.

The experiment was conducted using X-ray diffraction at room temperature on a crystal prepared from a purified enzyme. One of the features of MicroMAX is that the experimental setup can handle even small amounts of samples, so-called microcrystals. It is important as it lets the researchers study samples that cannot be made to form large crystals and extend investigations into new areas.

“We aim to carry out time-resolved studies using microcrystals of urocanate reductase to further clarify its enzymatic mechanism. We are also looking forward to using MicroMAX in other projects involving medically interesting proteins, which only yield microcrystals,” concludes Raminta Venskutonyte.

Read more om the MAX IV website

Image: Raminta Venskutonyte in the experiment hutch at beamline MicroMAX

Newly identified protein could help fight cancer

Newly identified protein could help fight cancer

Researchers from the University of British Columbia (UBC) have identified a new protein that helps an oral bacterium thrive in other locations around the body. The discovery could eventually lead to the development of new drugs that specifically target the protein.

“This bacterium is common in the mouths of humans and generally doesn’t cause disease in that location. However, it can travel through the bloodstream to other areas of the body, which leads to some pretty big health concerns,” says Dr. Kirsten Wolthers, Associate Professor of Biochemistry and Microbiology at UBC’s Okanagan Campus.

Most notably, this bacteria is prevalent in the tumors of colorectal cancer patients. The presence of the bacteria can contribute to tumor growth, spread of cancer to other sites in the body, and resistance to chemotherapy.

With the help of the CMCF beamline at the Canadian Light Source (CLS), located at the University of Saskatchewan, Wolthers and her colleagues determined that the new protein they identified enables the bacteria to take essential nutrients, such as iron, from our blood cells.

Read more on the CLS website

Image: Alexis Gauvin, inspecting a protein sample for particulate matter, using the glove box. Gauvin is a biochemistry student and a member of Dr. Kirsten Wolthers’s research group in the Department of Chemistry, University of British Columbia (Okanagan Campus).

Magnetotactic microorganisms studied through materials science and advanced imaging

Magnetotactic microorganisms studied through materials science and advanced imaging

 Researchers from the Bioscience and Biotechnology Institute of Aix-Marseille (BIAM) have recently published a new work in the journal Proceedings of the National Academy of Science. The study reveals a singular association between magnetotactic bacteria and their host, a unicellular eukaryote (protist).

Magnetoreception is a function unique in the world of the living. Microorganisms are capable of perceiving and reacting to fluctuations in their environment: temperature, light, pressure, gravity, etc. The Earth’s magnetic field is also perceived by certain microorganisms: magnetotactic bacteria, whose mobility is guided by geomagnetic field lines. Magnetoreception guides their movement in aquatic sediments while locating more easily specific depths of the surface. In the microbial world, magnetoreception is based on the synthesis of intracellular chains of magnetic nanocrystals. It is currently the only form of geolocation to have been characterized by scientists.

All the microorganisms sensitive to the magnetic field described so far associate magnetoreception with sensory systems dedicated to certain physicochemical signals, thanks to which they can navigate towards or away from specific substances. This navigation behavior is called magnetotaxis and was, until recently, only observed in magnetotactic bacteria present in areas with strong chemical gradients such as aquatic sediments. By guiding their movement along vertical lines rather than in three-dimensions, their magnetism allows them to more easily find the zone where conditions are optimal for their growth. However, findings by researchers at the BIAM, revealed in 2019 that protists had also acquired this ability through a singular strategy. Some flagellated protists acquired magnetotaxis by associating with magnetotactic bacteria attached to their surface, becoming indispensable symbionts during evolution. This discovery, “revealed that magnetotaxis was performed collectively, with the eukaryotic host enabling swimming and perception of the chemical environment on one hand and the bacterial symbionts producing the nano-sized magnetic needles on the other. However, we did not yet uncover how these partners interacted from a physical point of view and how the magnetic properties are formed,” says Christopher Lefèvre, co-coordinator of the study.


When microbiology meets materials science and advanced imaging techniques

The study of living systems interactions at the microscopic scale would still be inaccessible without interdisciplinarity of scientists equipped with advanced scientific techniques. “Studying such an environmental biological system is difficult due to their size, low abundance and lack of models in culture, pushing technological limits,”comments Daniel Chevrier, CNRS researcher at BIAM, first author and also co-coordinator of the study. Researchers had to deploy “an arsenal of approaches and technologies”, including synchrotron-based X-ray microscopy at MISTRAL beamline of the ALBA Synchrotron.

Read more on the ALBA website

Image: Magnetotactic holobiont – the host is a unicellular eukaryote with magnetotactic bacteria on its surface

Undermining the foundations of bacterial resistance

Undermining the foundations of bacterial resistance

Scientists from the University of Guelph have used the Canadian Light Source (CLS) at the University of Saskatchewan to better understand how several infectious bacteria, including E. coli., build a protective sugar-based barrier that helps cloak their cells.

Published in the Journal of Biological Chemistry, the Guelph research provides the very early steps toward new treatments for E. coli and a whole range of bacteria. Their particular focus is on strains of E. coli that cause urinary tract and bloodstream infections, particularly those that are antibiotic resistant.

The research is looking to understand the enzyme that many infectious bacteria use to build the foundations of their protective capsule. The capsule helps shield the bacterium from attack by the human immune system and exists in many clinically distinct variants.

Making vaccines or drugs that targets the capsule itself directly is impractical as such treatments would target only a few bacteria. Instead, the Guelph team is focused on a key enzyme that builds the capsule foundation. This foundation could serve as a common point of attack, allowing a single treatment for several key pathogens infecting humans and livestock.

“We are interested in the machinery that builds the bacterium’s protective layer,” said Dr. Chris Whitfield, Professor Emeritus in the Department of Molecular and Cellular Biology. “By understanding and targeting the machinery, we can render the pathogen unable to survive in the host”.

Read more on the Canadian Light Source website

Image : Matthew Kimber, Chris Whitfield, and enzyme

Scientists discover potential method to starve the bacteria that cause Tuberculosis

Scientists discover potential method to starve the bacteria that cause Tuberculosis

By deepening our understanding of how Tuberculosis bacteria feed themselves, University of Guelph researchers have identified a potential target for drug treatment. The team used the Canadian Light Source (CLS) at the University of Saskatchewan to image the bacteria in fine detail.

The infectious disease Tuberculosis (TB) is one of the leading causes of death worldwide. While rates of TB in Canada have remained relatively static since the 1980s, the disease disproportionately affects Indigenous populations. With TB-causing bacteria becoming increasingly resistant to antibiotics, researchers and drug makers are eager to find new, more effective treatments.

Researchers have known for some time that the bacteria that causes TB (Mycobacterium tuberculosis) uses our body’s cholesterol – a steroid – as a food source. Other relatives of the bacteria that do not cause disease share its ability to break down steroids. In this study, the University of Guelph team identified the structure of an enzyme (acyl CoA dehydrogenase) involved in steroid degradation in another member of the same bacteria family, called Thermomonospora curvata.

Read more on the CLS Website

Image: This rendering shows the shape of a tunnel (orange) where the substrate binds. Any drugs targeting this enzyme would need to fit to this pocket.

Helping our immune systems bypass antibiotic resistance

Helping our immune systems bypass antibiotic resistance

Over 700,000 people die each year due to drug-resistant diseases and this figure could increase to 10 million per year by 2050, according to a 2019 report.

As the search continues for new antibiotics to treat drug-resistant infections, a group of researchers used the Canadian Light Source (CLS) at the University of Saskatchewan to address the problem from a different direction, by trying to weaken the ability of bacteria to develop resistance in the first place.

“The goal is to knock the bacterial cells down in terms of their resistance,” said Dr. Anthony Clarke, Professor and Dean of Science at Wilfrid Laurier University and adjunct professor at the University of Guelph. “We haven’t been successful over the last 30 years in finding new classes of antibiotics so, in the short term, we’re trying to weaken the cells so our own immune system can take over to fight infection.”

The target for his team’s work is peptidoglycan, which gives bacterial cell walls their rigidity. “Think of it as building a brick wall around the bacteria’s cells,” said Clarke. Since peptidoglycan can be broken down by lysozyme, an enzyme that exists in human immune systems, bacteria have developed strategies that block these enzymes by modifying their peptidoglycan, thereby “cementing the bricks in place,” and resisting our defences.

Read more on the Canadian Light Source website

Image: Dr. Clarke inspecting flasks of bacterial cultures in a student laboratory.

Preventing hospital-acquired pneumonia

Preventing hospital-acquired pneumonia

Researchers used the Canadian Light Source (CLS) at the University of Saskatchewan to identify a previously unrecognized family of enzymes that put us at risk for deadly diseases.

Klebsiella pneumoniae is responsible for a variety of hospital-acquired infections such as pneumonia and sepsis. The bacterium has become increasingly resistant to antibiotics, making it a focus of interest for health care professionals and researchers.

>Read more on the Canadian Light Source website

Image: Chris Whitfield has been working on polysaccharides like LPS throughout his career.

Discoveries map out CRISPR-Cas defence systems in bacteria

Discoveries map out CRISPR-Cas defence systems in bacteria

For the first time, researchers at the University of Copenhagen have mapped how bacterial cells trigger their defence against outside attacks. This could affect how diseases are fought in the future.

With the aid of highly advanced microscopes and synchrotron sources, researchers from the University of Copenhagen have gained critical insight into how bacteria function as defence mechanisms against attacks from other bacteria and viruses. The study, which has just been published in the renowned journal, Nature Communications, also describes how the defence systems can be activated on cue. This discovery can turn out to be an important cornerstone in fighting diseases in the future.

The researchers have shown how a cell attacked by a virus activates a molecule called COA (Cyclic Oligoadenylate), which in turn activates a so-called protein complex called CSX1 to eradicate the attacker.

>Read more on the MAX IV website

Image: Model of the CSX1 protein complex.

The future of fighting infections

The future of fighting infections

Scientists analyze 3D model of proteins from disease-causing bacteria at the CLS.

Millions of people are affected by the Streptococcus pneumoniae bacterium, which can cause sinus infections, middle ear infections and more serious life-threatening diseases, like pneumonia, bacteremia, and meningitis. Up to forty percent of the population are carriers of this bacterium.
Researchers from the University of Victoria (UVic) used the Canadian Light Source (CLS) at the University of Saskatchewan to study proteins that the pathogen uses to break down sugar chains (glycans) present in human tissue during infections. These proteins are key tools the bacterium uses to cause disease.

They used the Canadian Macromolecular Crystallography Facility (CMCF) at the CLS to determine the three-dimensional structure of a specific protein, an enzyme, that the bacterium produces to figure out how it interacts with and breaks down glycans.

>Read more on the Canadian Light Source website

Image: The 3D structure of an enzyme from the disease-causing bacterium Streptococcus pneumoniae.

Research on how light-harvesting bacteria toggle off and on

Research on how light-harvesting bacteria toggle off and on

The results could have long-range implications for artificial photosynthesis and optogenetics—the use of light to selectively activate biological processes.

Cyanobacteria are water-dwelling microbes capable of absorbing sunlight and converting it into chemical energy through photosynthesis. Long ago, ancient versions of these bacteria were incorporated into plant cells, where they eventually evolved into chloroplasts, the organelles responsible for carrying out photosynthesis in green plants. Today, in seeking to develop artificial photosynthesis to harness the sun’s abundant energy, scientists look to cyanobacteria to better understand the nuts and bolts of how natural photosynthesis works.

Cyanobacterial “off switch”

One topic of interest is how cyanobacteria respond to too much light. If a sunlight-harvesting system becomes overloaded with absorbed solar energy, it most likely will suffer some form of damage. Nature has solved the problem in cyanobacteria through a protective mechanism—an energy-quenching “off switch” in which excess solar energy is safely dissipated as heat.

>Read more on the Advanced Light Source at BNL

Illustration: X-ray footprinting provides time-resolved information about where key conformational changes occur. On the left is the overall OCP structure. The two structures on the right highlight local areas with increasing protein packing over time (blue shading) and areas with decreasing protein packing over time (red shading). The changes in accessibility are initiated by the movement of the carotenoid molecule (magenta chain).