Phage P22 tailspike protein: Crystal structure of the head-binding domain at 2.3 angstrom, fully refined structure of the endorhamnosidase at 1.56 angstrom resolution, and the molecular basis of O-antigen recognition and cleavage
Phage P22 tailspike protein: Crystal structure of the head-binding domain at 2.3 angstrom, fully refined structure of the endorhamnosidase at 1.56 angstrom resolution, and the molecular basis of O-antigen recognition and cleavage
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DOI：
10.1006/jmbi.1997.0922
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发表时间：
1997-04-11
影响因子：
5.6
通讯作者：
Huber, R
中科院分区：
文献类型：
--
作者：
Steinbacher, S;Miller, S;Huber, R
沙门氏菌噬菌体P22的尾钉蛋白是一种具有受体结合和破坏活性的病毒黏附蛋白。它识别A、B和D1群细胞表面脂多糖的O-抗原性重复单位为受体，但也通过内切糖苷酶(内切糖苷酶)活性使其受体失活。在噬菌体P22组装的最后一步中，六个同源三聚体尾钉分子通过它们的N末端头部结合结构域非共价连接到DNA注射装置上。我们报道了P22 Tail Spike蛋白头部结合结构域的晶体结构，分辨率为2.3埃，用重组碲蛋氨酸衍生物和非晶体对称性平均法求解。三聚体穹顶状结构由两个垂直的β-折叠形成，每个亚单位分别有五条和三条链，并覆盖了在C末端受体结合和切割片段结构中观察到的三螺旋束，这里报道了在1.56埃分辨率下完全精制后的结构。在受体结合片段的中央部分，13个完整转角的三个平行的β-螺旋并列在一起，而三个多肽链朝着它们的C末端合并成一个单一的结构域，并在与β-螺旋部分的连接处紧密交错。详细描述了以1.8埃分辨率测定的鼠伤寒沙门氏菌、肠炎沙门氏菌和伤寒沙门氏菌253Ty的受体片段的复杂结构。插入到β-螺旋中形成O-抗原结合槽，该槽还含有活性部位残基Asp392、Asp395和Glu359。在尾刺蛋白的完整结构中，头部结合部分和受体结合部分可能由一个灵活的铰链连接，其功能可能是处理暴露在暴露的150埃长尾刺上的剪切力，或者允许它们在感染过程中弯曲。(C)1997年学术出版社有限公司。
The tailspike protein of Salmonella phage P22 is a viral adhesion protein with both receptor binding and destroying activities. It recognises the O-antigenic repeating units of cell surface lipopolysaccharide of serogroup A, B and D1 as receptor, but also inactivates its receptor by endoglycosidase (endorhamnosidase) activity. In the final step of bacteriophage P22 assembly six homotrimeric tailspike molecules are non-covalently attached to the DNA injection apparatus, mediated by their N-terminal, head-binding domains. We report the crystal structure of the head-binding domain of P22 tailspike protein at 2.3 Angstrom resolution, solved with a recombinant telluromethionine derivative and non-crystallographic symmetry averaging. The trimeric dome-like structure is formed by two perpendicular beta-sheets of five and three strands, respectively in each subunit and caps a three-helix bundle observed in the structure of the C-terminal receptor binding and cleaving fragment, reported here after full refinement at 1.56 Angstrom resolution. In the central part of the receptor binding fragment, three parallel beta-helices of 13 complete turns are associated side-by-side, while the three polypeptide strands merge into a single domain towards their C termini, with close interdigitation at the junction to the beta-helix part. Complex structures with receptor fragments from S. typhimurium, S. enteritidis and S. typhi253Ty determined at 1.8 Angstrom resolution are described in detail. Insertions into the beta-helix form the O-antigen binding groove, which also harbours the active site residues Asp392, Asp395 and Glu359. In the intact structure of the tailspike protein, head-binding and receptor-binding parts are probably linked by a flexible hinge whose function may be either to deal with shearing forces on the exposed, 150 Angstrom long tailspikes or to allow them to bend during the infection process. (C) 1997 Academic Press Limited.