ジャーナル: Proc Natl Acad Sci U S A / 年: 2010 タイトル: Structure of lactococcal phage p2 baseplate and its mechanism of activation. 著者: Giuliano Sciara / Cecilia Bebeacua / Patrick Bron / Denise Tremblay / Miguel Ortiz-Lombardia / Julie Lichière / Marin van Heel / Valérie Campanacci / Sylvain Moineau / Christian Cambillau / 要旨: Siphoviridae is the most abundant viral family on earth which infects bacteria as well as archaea. All known siphophages infecting gram+ Lactococcus lactis possess a baseplate at the tip of their ...Siphoviridae is the most abundant viral family on earth which infects bacteria as well as archaea. All known siphophages infecting gram+ Lactococcus lactis possess a baseplate at the tip of their tail involved in host recognition and attachment. Here, we report analysis of the p2 phage baseplate structure by X-ray crystallography and electron microscopy and propose a mechanism for the baseplate activation during attachment to the host cell. This approximately 1 MDa, Escherichia coli-expressed baseplate is composed of three protein species, including six trimers of the receptor-binding protein (RBP). RBPs host-recognition domains point upwards, towards the capsid, in agreement with the electron-microscopy map of the free virion. In the presence of Ca(2+), a cation mandatory for infection, the RBPs rotated 200 degrees downwards, presenting their binding sites to the host, and a channel opens at the bottom of the baseplate for DNA passage. These conformational changes reveal a novel siphophage activation and host-recognition mechanism leading ultimately to DNA ejection.
名称: Over-expressed Lactococcal phage p2 baseplate / タイプ: sample / ID: 1000 集合状態: One homotrimer of ORF16 binds to two hexamers of ORF15 and binds to six homotrimers of ORF18 Number unique components: 1