RESUMO
We report that the cold shock protein CspA of Staphylococcus aureus is required for maximal production of pigment. Results from transcriptional studies revealed that loss of CspA resulted in decreased expression of genes needed for the biosynthesis of 4,4'-diaponeurosporene and the alternative sigma factor SigB.
Assuntos
Proteínas de Bactérias/metabolismo , Pigmentos Biológicos/biossíntese , Staphylococcus aureus/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Bactérias/genética , Carotenoides/genética , Carotenoides/metabolismo , Regulação Bacteriana da Expressão Gênica , Fator sigma/genética , Fator sigma/metabolismo , Fatores de Transcrição/genética , Triterpenos/metabolismoRESUMO
A Tn551 insertional library of Staphylococcus aureus strain ISP479 was challenged with an antimicrobial peptide (CG 117-136) derived from human neutrophil cathepsin G (CG). After repeated selection and screening of surviving colonies, a mutant was identified that expressed increased resistance to CG 117-136. Southern hybridization analysis revealed that the Tn551 insert in this mutant (SK1) was carried on a 10.6-kb EcoRI chromosomal DNA fragment. Subsequent physical mapping of this Tn551 insert revealed that it was positioned between a putative promoter sequence and the translational start codon of the cspA gene, which encodes a protein (CspA) highly similar to the major cold shock proteins CspA and CspB of Escherichia coli and Bacillus subtilis, respectively. This Tn551 insertion as well as a separate deletion-insertion mutation in cspA decreased the capacity of S. aureus to respond to the stress of cold shock and increased resistance to CG 117-136. The results indicate for the first time that a physiologic link exists between bacterial susceptibility to an antimicrobial peptide and a stress response system.
