National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2010

17. SrtG pilus structures on the cell surface of virulent Streptococcus suis strain and their assembly mechanisms

 Japanese

  The srtG cluster is one of the putative pilus gene clusters possessed by virulent Streptococcus suis strains. It consists of 1 pilin polymerase (sortase) gene (srtG) and 2 putative pilin subunit genes (sgp1 and sgp2). In this study, by constructing mutants for each of the genes in the cluster, and by both immunoblotting and immunogold electron microscopic analysis with antibodies against Sgp1 and Sgp2, we found that the srtG cluster mediates the expression of pilus-like structures in a virulent S. suis strain. In this pilus, Sgp1 forms the backbone whereas Sgp2 is incorporated as the accessory subunit. However, unlike other well-characterized gram-positive pili, the accessory subunit Sgp2 was required for polymerization of the backbone subunit Sgp1. Because homologues of this accessory pilus protein are encoded in several other gram-positive pilus gene clusters, in some types of pilus, accessory pilus proteins may contribute to backbone formation by a novel mechanism.
(Research Team for Bacterial/Parasitic Diseases)

References:

Okura M. et al. (2011) J. Bacteriol. 193 (4): 822-831

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