期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 285, 期 50, 页码 39079-39086出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M110.175646
关键词
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资金
- Marseille-Nice Geno-pole
- CNRS
- Agence Nationale de la Recherche [ANR-07-BLAN-0095]
- Ministere francais de l'enseignement superieur et de la recherche [22976-2006]
- National Institutes of Health [P41 RR-01081]
- Agence Nationale de la Recherche (ANR) [ANR-07-BLAN-0095] Funding Source: Agence Nationale de la Recherche (ANR)
P335 lactococcal phages infect the Gram(+) bacterium Lactococcus lactis using a large multiprotein complex located at the distal part of the tail and termed baseplate (BP). The BP harbors the receptor-binding proteins (RBPs), which allow the specific recognition of saccharidic receptors localized on the host cell surface. We report here the electron microscopic structure of the phage TP901-1 wild-type BP as well as those of two mutants bppL(-) and bppU(-), lacking BppL (the RBPs) or both peripheral BP components (BppL and BppU), respectively. We also achieved an electron microscopic reconstruction of a partial BP complex, formed by BppU and BppL. This complex exhibits a tripod shape and is composed of nine BppLs and three BppUs. These structures, combined with light-scattering measurements, led us to propose that the TP901-1 BP harbors six tripods at its periphery, located around the central tube formed by ORF46 (Dit) hexamers, at its proximal end, and a ORF47 (Tal) trimer at its distal extremity. A total of 54 BppLs (18 RBPs) are thus available to mediate host anchoring with a large apparent avidity. TP901-1 BP exhibits an infection-ready conformation and differs strikingly from the lactococcal phage p2 BP, bearing only 6 RBPs, and which needs a conformational change to reach its activated state. The comparison of several Siphoviridae structures uncovers a close organization of their central BP core whereas striking differences occur at the periphery, leading to diverse mechanisms of host recognition.
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