title: Putative mannose-specific phosphotransferase system component IID represses expression of suilysin in serotype 2 Streptococcus suis.
abstract: In this study, we generated a genomic mutant library from a North American strain of serotype 2 Streptococcus suis using the pGh9:ISS1 transposition vector. Suilysin is the hemolysin made by S. suis. A hyper-hemolytic mutant was identified by screening for hemolytic phenotype using media with human blood. The hyper-hemolytic phenotype was characterised by a quantitative hemolysis microplate method. The use of green fluorescent protein (GFP) as a reporter also showed that suilysin gene expression was greater in the mutant. DNA sequence analysis of 3.8 kb surrounding the ISS1 insertion site revealed four open reading frames (ORFs) with three consecutive ORFs that belong to a putative mannose-specific phosphotransferase system (PTS). The S. suis gene homologous to mannose permease IID, manN, was interrupted by the transposon. A complementation test showed that manN repressed the expression of suilysin and the absence of manN was responsible for the hyper-hemolytic phenotype. However, both wild type and isogenic hyper-hemolytic mutant S. suis fermented mannose, glucose and lactose. Thus, despite its potential roles in carbohydrate transport, phosphorylation and metabolism, the manN homologue in the putative mannose-specific PTS regulates gene expression in S. suis.
authors.affiliation: 120 Veterinary Road, Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Sask., Canada S7N 5E3.
authors.forename: Shichun
authors.initials: S
authors.lastname: Lun
authors.forename: P J
authors.initials: PJ
authors.lastname: Willson
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D050260:Carbohydrate Metabolism; D004269:DNA, Bacterial / Q000737:chemistry; D005285:Fermentation; D005434:Flow Cytometry; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000235:genetics; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D049408:Luminescent Agents; D009154:Mutation; D016366:Open Reading Frames; D009930:Organic Chemicals; D010641:Phenotype; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017011:Streptococcus suis / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D004269:DNA, Bacterial; D006460:Hemolysin Proteins; D049408:Luminescent Agents; D009930:Organic Chemicals; C104760:suilysin; D049452:Green Fluorescent Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C037992:phosphoenolpyruvate-mannose phosphotransferase