Structural highlights
Function[PAPA_ECOLX] Polymerizes to form the thick (6.8 nm in diameter) rod of the pilus (also called fimbria). The rod is a right-handed helical cylinder with 3.28 PapA subunits per turn. Pili are polar filaments radiating from the surface of the bacterium to a length of 0.5-1.5 micrometers and numbering 100-300 per cell, and enable bacteria to colonize the epithelium of specific host organs. Publication Abstract from PubMedTypes 1 and P pili are prototypical bacterial cell-surface appendages playing essential roles in mediating adhesion of bacteria to the urinary tract. These pili, assembled by the chaperone-usher pathway, are polymers of pilus subunits assembling into two parts: a thin, short tip fibrillum at the top, mounted on a long pilus rod. The rod adopts a helical quaternary structure and is thought to play essential roles: its formation may drive pilus extrusion by preventing backsliding of the nascent growing pilus within the secretion pore; the rod also has striking spring-like properties, being able to uncoil and recoil depending on the intensity of shear forces generated by urine flow. Here, we present an atomic model of the P pilus generated from a 3.8 A resolution cryo-electron microscopy reconstruction. This structure provides the molecular basis for the rod's remarkable mechanical properties and illuminates its role in pilus secretion. Structure of a Chaperone-Usher Pilus Reveals the Molecular Basis of Rod Uncoiling.,Hospenthal MK, Redzej A, Dodson K, Ukleja M, Frenz B, Rodrigues C, Hultgren SJ, DiMaio F, Egelman EH, Waksman G Cell. 2015 Dec 22. pii: S0092-8674(15)01568-8. doi: 10.1016/j.cell.2015.11.049. PMID:26724865[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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