ジャーナル: Mol Cell / 年: 2016 タイトル: Calcium-Driven Folding of RTX Domain β-Rolls Ratchets Translocation of RTX Proteins through Type I Secretion Ducts. 著者: Ladislav Bumba / Jiri Masin / Pavel Macek / Tomas Wald / Lucia Motlova / Ilona Bibova / Nela Klimova / Lucie Bednarova / Vaclav Veverka / Michael Kachala / Dmitri I Svergun / Cyril Barinka / Peter Sebo / 要旨: Calcium-binding RTX proteins are equipped with C-terminal secretion signals and translocate from the Ca(2+)-depleted cytosol of Gram-negative bacteria directly into the Ca(2+)-rich external milieu, ...Calcium-binding RTX proteins are equipped with C-terminal secretion signals and translocate from the Ca(2+)-depleted cytosol of Gram-negative bacteria directly into the Ca(2+)-rich external milieu, passing through the "channel-tunnel" ducts of type I secretion systems (T1SSs). Using Bordetella pertussis adenylate cyclase toxin, we solved the structure of an essential C-terminal assembly that caps the RTX domains of RTX family leukotoxins. This is shown to scaffold directional Ca(2+)-dependent folding of the carboxy-proximal RTX repeat blocks into β-rolls. The resulting intramolecular Brownian ratchets then prevent backsliding of translocating RTX proteins in the T1SS conduits and thereby accelerate excretion of very large RTX leukotoxins from bacterial cells by a vectorial "push-ratchet" mechanism. Successive Ca(2+)-dependent and cosecretional acquisition of a functional RTX toxin structure in the course of T1SS-mediated translocation, through RTX domain folding from the C-terminal cap toward the N terminus, sets a paradigm that opens for design of virulence inhibitors of major pathogens.
分子量: 16024.102 Da / 分子数: 1 / 断片: BLOCK V OF RTX DOMAIN (UNP RESIDUES 1529-1681) / 由来タイプ: 組換発現 詳細: The last 3 amino acids are too flexible to be fit in the electron density map. 由来: (組換発現) Bordetella pertussis (strain ATCC 9797 / DSM 5571 / NCTC 10739 / 18323) (百日咳菌) 遺伝子: cya, cyaA, BN118_0468 / プラスミド: PET42B / 発現宿主: Escherichia coli BL21(DE3) (大腸菌) / 参照: UniProt: J7QLC0, アデニル酸シクラーゼ