User:Fadel A. Samatey/FlhBc I

Interactive 3D Complement in Proteopedia

Inhibition of a type III secretion system by the deletion of a short loop in one of its membrane proteins.

Vladimir A. Meshcheryakov, Akio Kitao, Hideyuki Matsunami and Fadel A. Samatey. Acta Cryst. D69: 812-820 (2013). doi:10.1107/S0907444913002102

Brief IntroductionBrief Introduction

FlhB is a membrane protein that is part of the flagellum-specific secretion apparatus. It is required for secretion of flagellar proteins, and for bacterial motility. FlhB is paralogous to a protein in the virulence type III secretion system. FlhB has a hydrophobic integral membrane domain, predicted to have four transmembrane helices, a flexible linker that is highly conserved and essential for function, and a cytoplasmic domain. The present study reports the structures of the cytoplasmic domains of two bacterial taxa. (Please see the publication for a more detailed introduction.)

Molecular Tour: FlhBc StructuresMolecular Tour: FlhBc Structures

Salmonella FlhB from Salmonella typhimurium consists of 383 amino acids. The cytoplasmic domain 219-383 (length 165, 43% of full length) was crystallized. The resulting model 3b0z includes coordinates for residues 229-353 (length 125, 76% of the crystallized length). The asymmetric unit contains a single molecule (). As explained in the publication, the position of the long alpha helix appears to be stabilized by crystal contacts (not shown). The chain is . This is believed to be autocatalytic cleavage involved in the transition of the export apparatus from hook to filament mode. Mutations that prevent this cleavage render the bacteria non-motile. Aquifex FlhB from the thermophile Aquifex aeolicus is shorter, 350 residues (vs. 383 for S. typhimurium), with 32% sequence identity. Residues 213-350 (length 138) were crystallized, and the resulting model 3b1s has in the asymmetric unit. The molecule displayed in the comparison in the next section, with chains designated C and D, was chosen because it has the lowest average temperature factor (66.2, vs. 84.7 and 72.6 for A,B and E,F respectively). It has coordinates for 232-337 (length 106, 77% of the crystallized segment), cleaved at NPTH between Asn263 and Pro264. Comparison The FlhBc Salmonella 3D structure is very similar</scene> to that of Aquifex. 102 alpha carbons align with an RMSD of 1.0 Å. Their FlhB's have 32% sequence identity. , then click the button below to do a structural alignment.

spinqualitylabelsall models Cytoplasmic domain of FlhB Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Notes for DevelopersNotes for Developers

• File:Workbench 3b0z.pdb.gz
• File:Workbench 3b1s.pdb.gz
• File:Workbench 3b0z 3b1sCD.pdb 1.1 is 3b0z(St) while 1.2 is 3b1s chains C and D. Not aligned.
• File:Workbench 3b0z 3b1sCD aligned.pdb