6e14

Handover mechanism of the growing pilus by the bacterial outer membrane usher FimDHandover mechanism of the growing pilus by the bacterial outer membrane usher FimD

6e14, resolution 4.00Å Show:Asymmetric Unit Biological Assembly Structural highlights 6e14 is a 5 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 4Å Experimental data: Check Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FIMD_ECOLI Involved in the export and assembly of FimA fimbrial subunits across the outer membrane. Publication Abstract from PubMed Pathogenic bacteria such as Escherichia coli assemble surface structures termed pili, or fimbriae, to mediate binding to host-cell receptors(1). Type 1 pili are assembled via the conserved chaperone-usher pathway(2-5). The outer-membrane usher FimD recruits pilus subunits bound by the chaperone FimC via the periplasmic N-terminal domain of the usher. Subunit translocation through the beta-barrel channel of the usher occurs at the two C-terminal domains (which we label CTD1 and CTD2) of this protein. How the chaperone-subunit complex bound to the N-terminal domain is handed over to the C-terminal domains, as well as the timing of subunit polymerization into the growing pilus, have previously been unclear. Here we use cryo-electron microscopy to capture a pilus assembly intermediate (FimD-FimC-FimF-FimG-FimH) in a conformation in which FimD is in the process of handing over the chaperone-bound end of the growing pilus to the C-terminal domains. In this structure, FimF has already polymerized with FimG, and the N-terminal domain of FimD swings over to bind CTD2; the N-terminal domain maintains contact with FimC-FimF, while at the same time permitting access to the C-terminal domains. FimD has an intrinsically disordered N-terminal tail that precedes the N-terminal domain. This N-terminal tail folds into a helical motif upon recruiting the FimC-subunit complex, but reorganizes into a loop to bind CTD2 during handover. Because both the N-terminal and C-terminal domains of FimD are bound to the end of the growing pilus, the structure further suggests a mechanism for stabilizing the assembly intermediate to prevent the pilus fibre diffusing away during the incorporation of thousands of subunits. Handover mechanism of the growing pilus by the bacterial outer-membrane usher FimD.,Du M, Yuan Z, Yu H, Henderson N, Sarowar S, Zhao G, Werneburg GT, Thanassi DG, Li H Nature. 2018 Oct 3. pii: 10.1038/s41586-018-0587-z. doi:, 10.1038/s41586-018-0587-z. PMID:30283140 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Adhesin 3D structures