NEWS In a new study, researchers at the universities of Umeå and Cagliari reveal the three-dimensional structure of one of the large protein complexes in the cell envelope of the radiation-resistant bacterium Deinococcus radiodurans. The results are published in the prestigious Journal of Biological Chemistry.
the structure of the SDBC with its typical three-pore organization and ligands, seen from the side (left) and from the top (right). In pink, it is highlighted the surface of the complex which, due to presence of deinoxanthin and native lipids, acts as a screen.
ImageDomenica FarciNew knowledge is important for future applications in biomedicine for the development of new generation antibiotics and in nanotechnologies for the development of new biomaterials.
Deinococcus radiodurans is named by the Guinness Book of World Records as the world's toughest bacteria. This extremophile has incredible abilities to resist strong dehydration, heat, and electromagnetic stress; in particular, due to its ability to withstand a dose of gamma radiation 15 000 times higher than those sufficient to kill a man, this bacterium is currently a unique organism of its kind.
In the current study, the research team has studied a protein complex, important in proving to this bacterium resistance to ultraviolet radiation, with the scientific name S-layer deinoxanthin-binding complex (SDBC), is. In the study it was possible to locate the components granting protection functions to this complex and define its organization.
“Fundamental for its shielding functions are not only its extraordinary amino acidic composition, but also the presence of metal ions Iron and Copper and powerful antioxidants such as deinoxanthin, a pigment of the carotenoids family, and specific phospholipids, all exclusive to this bacterium,” says Domenica Farci, post doc in Wolfgang Schröder lab at the Department of Chemistry at Umeå University.
She has performed the study together with Professor Dario Piano at Cagliari University in Italy.
Furthermore, the study revealed how, by covering the entire cell surface and in addition to acting as a shield against ultraviolet radiation, the SDBC allows the exchange of nutrients with the environment avoiding acting as an obstacle. The channel proteins that perform this function are called porins and in the work it emerges that SDBC is 7 to 10 times larger than the porins known so far.
The obtained new knowledge is important for future applications in biomedicine for the development of new generation antibiotics and in nanotechnologies for the development of new biomaterials that can be used in photonics and to produce biosensors.
Farci D, Haniewicz P, de Sanctis D, Iesu L, Kereïche S, Winterhalter M, Piano
D.: The cryo-EM structure of the S-layer deinoxanthin-binding complex of Deinococcus radiodurans informs properties of its environmental interactions. Journal of Biological Chemistry (2022), doi: https://doi.org/10.1016/j.jbc.2022.102031
