Phage P22 tailspike protein: crystal structure of the head-binding domain at 2.3 A, fully refined structure of the endorhamnosidase at 1.56 A resolution, and the molecular basis of O-antigen recognition and cleavage.

摘要: Abstract The tailspike protein of Salmonella phage P22 is a viral adhesion with both receptor binding and destroying activities. It recognises the O-antigenic repeating units cell surface lipopolysaccharide serogroup A, B D1 as receptor, but also inactivates its by endoglycosidase (endorhamnosidase) activity. In final step bacteriophage assembly six homotrimeric molecules are non-covalently attached to DNA injection apparatus, mediated their N-terminal, head-binding domains. We report crystal structure domain at 2.3 A resolution, solved recombinant telluromethionine derivative non-crystallographic symmetry averaging. trimeric dome-like formed two perpendicular β-sheets five three strands, respectively in each subunit caps three-helix bundle observed C-terminal cleaving fragment, reported here after full refinement 1.56 resolution. central part parallel β-helices 13 complete turns associated side-by-side, while polypeptide strands merge into single towards C termini, close interdigitation junction β-helix part. Complex structures fragments from S. typhimurium, enteritidis typhi253Ty determined 1.8 resolution described detail. Insertions form O-antigen groove, which harbours active site residues Asp392, Asp395 Glu359. intact protein, receptor-binding parts probably linked flexible hinge whose function may be either deal shearing forces on exposed, 150 long tailspikes or allow them bend during infection process.