title: Steady-state staphylococcal enterotoxin type C mRNA is affected by a product of the accessory gene regulator (agr) and by glucose.
abstract: The effects of the accessory gene regulator (agr) and glucose on staphylococcal enterotoxin type C (SEC) gene (sec+) expression were examined. For the agr studies, a Tn551 insertionally inactivated agr was transferred into two different sec+ Staphylococcus aureus strains. Western blot (immunoblot) analysis showed that each of the sec+ Agr- derivatives produced less extracellular SEC than their Agr+ parent strains. Analysis of Northern (RNA) blots was consistent with at least part of the agr effect being at the level of steady-state sec+ mRNA. We examined the glucose effect on sec+ expression by utilizing both a fermentor system with a completely defined amino acid-containing medium in which the pH of the medium was maintained at 6.5 and a shake flask system with a complex medium in which the pH was allowed to fluctuate during bacterial growth. In both systems, samples from the cultures containing glucose had less extracellular SEC and less steady-state sec+ mRNA compared with the control cultures which lacked glucose. An intact agr was not required for the glucose effect on sec+ expression; MJB407, an Agr- sec+ strain, produced more SEC and had more steady-state sec+ mRNA when grown in medium that lacked glucose compared with medium that contained glucose.
authors.affiliation: University of Wisconsin-Madison 53706.
authors.forename: L B
authors.initials: LB
authors.lastname: Regassa
authors.forename: J L
authors.initials: JL
authors.lastname: Couch
authors.forename: M J
authors.initials: MJ
authors.lastname: Betley
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D004768:Enterotoxins / Q000096:biosynthesis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D005947:Glucose / Q000378:metabolism*; D010957:Plasmids; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D014162:Transfection
chemical_list: D004768:Enterotoxins; D012333:RNA, Messenger; C034959:enterotoxin C, staphylococcal; D005947:Glucose