贪婪
噬菌体
化学
沙门氏菌
微生物学
结合位点
抗原
生物化学
蛋白质亚单位
血浆蛋白结合
生物
细菌
大肠杆菌
免疫学
遗传学
基因
作者
Dorothee Andres,Ulrich Baxa,Christin Hanke,Robert Seckler,Stefanie Barbirz
出处
期刊:Biochemical Society Transactions
[Portland Press]
日期:2010-09-24
卷期号:38 (5): 1386-1389
被引量:43
摘要
TSPs (tailspike proteins) are essential infection organelles of bacteriophage P22. Upon infection, P22TSP binds to and cleaves the O-antigen moiety of the LPS (lipopolysaccharide) of its Salmonella host. To elucidate the role of TSP during infection, we have studied binding to oligosaccharides and polysaccharides of Salmonella enterica Typhimurium and Enteritidis in vitro. P22TSP is a trimeric β-helical protein with a carbohydrate-binding site on each subunit. Octasaccharide O-antigen fragments bind to P22TSP with micromolar dissociation constants. Moreover, P22TSP is an endorhamnosidase and cleaves the host O-antigen. Catalytic residues lie at the periphery of the high-affinity binding site, which enables unproductive binding modes, resulting in slow hydrolysis. However, the role of this hydrolysis function during infection remains unclear. Binding of polysaccharide to P22TSP is of high avidity with slow dissociation rates when compared with oligosaccharides. In vivo, the infection of Salmonella with phage P22 can be completely inhibited by the addition of LPS, indicating that binding of phage to its host via TSP is an essential step for infection.
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