Structural biologists discover unexpected results at PETRA III at DESY in Germany.
An investigation at DESY’s X-ray light source PETRA III has revealed a surprising shape of an important scaffolding protein for biological cells. The scaffolding protein PDZK1 is comprised of four so-called PDZ domains, three linkers and a C-terminal tail. While bioinformatics tools had suggested that PDZK1’s PDZ domains and linkers would behave like beads on a string moving around in a highly flexible manner, the X-ray experiments showed that PDZK1 has a relatively defined L-shaped conformation with only moderate flexibility. The team led by Christian Löw from the Centre for Structural Systems Biology CSSB at DESY and Dmitri Svergun from the Hamburg branch of the European Molecular Biology Laboratory EMBL report their results in the journal Structure.
Similar to metal scaffolding which provides construction workers with access points to a building, scaffolding proteins mediate interactions between proteins situated on the membrane of the human cell. While the molecular structure of each of PDZK1’s four individual PDZ domains has been solved using X-ray crystallography and NMR spectroscopy, the overall arrangement of the domains in the protein as well as their interactions was not yet understood.
Image: Artistic shape interpretation of the scaffolding protein PDZK1. (Credit: Manon Boschard)tistic shape interpretation of the scaffolding protein PDZK1.
Credit: Manon Boschard