UNASSIGNED: The widely spread @entity5967 (also known as Group B Streptococcus, @entity5011 ) "hypervirulent" @entity23690 clone is strongly associated with @entity693 . The PI-2b locus is mainly found in @entity23690 strains but is also present in a few non @entity23690 @entity1 isolates such as the @entity22459 prototype strain A909. Here, we analysed the expression of the PI-2b pilus in the @entity23690 strain BM110 as compared to the non @entity23690 A909. Comparative genome analyses revealed the presence of a 43-base pair (bp) hairpin-like structure in the upstream region of PI-2b operon in all 26 @entity23690 genomes, which was absent in the 8 non- @entity23690 strains carrying the PI-2b locus. Deletion of this 43-bp sequence in strain BM110 resulted in a 3- to 5-fold increased transcription of PI-2b. Characterization of PI-2b promoter region in A909 and BM110 strains was carried out by RNAseq, primer extension, qRT-PCR and transcriptional fusions with gfp as reporter gene. Our results indicate the presence of a single promoter (Ppi2b) with a @entity1021 ( @entity1021 ) mapped 37 bases upstream of the start codon of the first PI-2b gene. The large operon of 16 genes located upstream of PI-2b codes for the group B @entity1735 (also known as antigen B), a major constituent of the bacterial cell wall. We showed that the hairpin sequence located between antigen B and PI-2b operons is a transcriptional terminator. In A909, increased expression of PI-2b probably results from read-through transcription from antigen B operon. In addition, we showed that an extended 5' promoter region is required for maximal transcription of gfp as a reporter gene in @entity5967 from Ppi2b promoter. Gene reporter assays performed in @entity7878 NZ9000, a related non-pathogenic Gram-positive species, revealed that @entity5011 -specific regulatory factors are required to drive PI-2b transcription. PI-2b expression is up-regulated in the BM110  covR mutant as compared to the parental BM110 strain, but this effect is probably indirect. Collectively, our results indicate that PI-2b expression is regulated in @entity5011 @entity23690 strains, which may confer a selective advantage in the @entity1 host either by reducing host immune responses and/or increasing their dissemination potential.

Regulation of PI-2b Pilus Expression in Hypervirulent XXXX ST-17 BM110.

@entity1 :: ('9606', 'Species') :: ['human'] @entity5967 :: ('1311', 'Species') :: ['Streptococcus agalactiae', 'S. agalactiae'] @entity1735 :: ('CHEBI:16646', 'Chemical') :: ['carbohydrate'] @entity1021 :: ('MESH:D020922', 'Disease') :: ['transcriptional start site', 'TSS'] @entity693 :: ('MESH:D008581', 'Disease') :: ['neonatal meningitis'] @entity22459 :: ('7982', 'Gene') :: ['ST-7'] @entity5011 :: ('MESH:D020275', 'Disease') :: ['GBS'] @entity23690 :: ('23705', 'Gene') :: ['ST17'] @entity7878 :: ('1358', 'Species') :: ['Lactococcus lactis strain']
@entity5967 :: (1311,Species) :: ['Streptococcus agalactiae']
