ジャーナル: J Biol Chem / 年: 2020 タイトル: Structural insights into the main S-layer unit of reveal a massive protein complex with porin-like features. 著者: Domenica Farci / Mehmet Alphan Aksoyoglu / Stefano Francesco Farci / Jayesh Arun Bafna / Igor Bodrenko / Matteo Ceccarelli / Joanna Kirkpatrick / Mathias Winterhalter / Sami Kereïche / Dario Piano / 要旨: In the extremophile bacterium , the outermost surface layer is tightly connected with the rest of the cell wall. This integrated organization provides a compact structure that shields the bacterium ...In the extremophile bacterium , the outermost surface layer is tightly connected with the rest of the cell wall. This integrated organization provides a compact structure that shields the bacterium against environmental stresses. The fundamental unit of this surface layer (S-layer) is the S-layer deinoxanthin-binding complex (SDBC), which binds the carotenoid deinoxanthin and provides both, thermostability and UV radiation resistance. However, the structural organization of the SDBC awaits elucidation. Here, we report the isolation of the SDBC with a gentle procedure consisting of lysozyme treatment and solubilization with the nonionic detergent -dodecyl-β-d-maltoside, which preserved both hydrophilic and hydrophobic components of the SDBC and allows the retention of several minor subunits. As observed by low-resolution single-particle analysis, we show that the complex possesses a porin-like structural organization, but is larger than other known porins. We also noted that the main SDBC component, the protein DR_2577, shares regions of similarity with known porins. Moreover, results from electrophysiological assays with membrane-reconstituted SDBC disclosed that it is a nonselective channel that has some peculiar gating properties, but also exhibits behavior typically observed in pore-forming proteins, such as porins and ionic transporters. The functional properties of this system and its porin-like organization provide information critical for understanding ion permeability through the outer cell surface of S-layer-carrying bacterial species.
名称: S-layer Deinoxanthin Binding Complex (SDBC) / タイプ: complex / ID: 1 / 親要素: 0 詳細: The SDBC is a hetero-oligomeric complex that constitutes the main protein complex of the S-layer of the radio-resistant bacterium Deinococcus radiodurans. This complex provides protection ...詳細: The SDBC is a hetero-oligomeric complex that constitutes the main protein complex of the S-layer of the radio-resistant bacterium Deinococcus radiodurans. This complex provides protection against UV radiation and shows gating properties by allowing ions currents across the cell wall.