ジャーナル: Cell / 年: 2008 タイトル: Fiber formation across the bacterial outer membrane by the chaperone/usher pathway. 著者: Han Remaut / Chunyan Tang / Nadine S Henderson / Jerome S Pinkner / Tao Wang / Scott J Hultgren / David G Thanassi / Gabriel Waksman / Huilin Li / 要旨: Gram-negative pathogens commonly exhibit adhesive pili on their surfaces that mediate specific attachment to the host. A major class of pili is assembled via the chaperone/usher pathway. Here, the ...Gram-negative pathogens commonly exhibit adhesive pili on their surfaces that mediate specific attachment to the host. A major class of pili is assembled via the chaperone/usher pathway. Here, the structural basis for pilus fiber assembly and secretion performed by the outer membrane assembly platform--the usher--is revealed by the crystal structure of the translocation domain of the P pilus usher PapC and single particle cryo-electron microscopy imaging of the FimD usher bound to a translocating type 1 pilus assembly intermediate. These structures provide molecular snapshots of a twinned-pore translocation machinery in action. Unexpectedly, only one pore is used for secretion, while both usher protomers are used for chaperone-subunit complex recruitment. The translocating pore itself comprises 24 beta strands and is occluded by a folded plug domain, likely gated by a conformationally constrained beta-hairpin. These structures capture the secretion of a virulence factor across the outer membrane of gram-negative bacteria.
SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW ... SHEET DETERMINATION METHOD: DSSP THE SHEETS PRESENTED AS "AA" IN EACH CHAIN ON SHEET RECORDS BELOW IS ACTUALLY AN 47-STRANDED BARREL THIS IS REPRESENTED BY A 48-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL.