Steady-state staphylococcal enterotoxin type C mRNA is affected by a product of the accessory gene regulator (agr) and by glucose.

AUTOR(ES)

Regassa, L B

RESUMO

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.

Documentos Relacionados

• Staphylococcal enterotoxin A gene (sea) expression is not affected by the accessory gene regulator (agr).
• Identification of sequences in c-myc mRNA that regulate its steady-state levels.
• Role of the accessory gene regulator (agr) in pathogenesis of staphylococcal osteomyelitis.
• Modulation of Bacillus subtilis levansucrase gene expression by sucrose and regulation of the steady-state mRNA level by sacU and sacQ genes.
• Glucose and nonmaintained pH decrease expression of the accessory gene regulator (agr) in Staphylococcus aureus.