Impact of sigB mutation on Staphylococcus aureus oxacillin and vancomycin resistance varies with parental background and method of assessment

Singh, Vipender; Schmidt, J; Jayaswal, Radheshyam K.; Wilkinson, Brian J.

doi:10.1016/s0924-8579(02)00359-x

Cited by 56 publications

(43 citation statements)

References 26 publications

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“…5), previous studies in other laboratories found that methicillin-resistant S. aureus and glycopeptideintermediate S. aureus isolates displayed increased resistance to methicillin (oxacillin) and vancomycin compared to their isogenic sigB-negative counterparts, respectively (30,44,49). These results suggest that the molecular components involved in resistance to cell wall antibiotics may differ from those that confer tolerance.…”

Section: Discussionmentioning

confidence: 92%

“…However, the precise role of these genes in the general stress response remains to be determined. Both the lrg and cid operons have been previously shown to be involved in penicillin-induced killing (20,42), and B has been shown to affect the resistance of S. aureus to various antibiotics, including teicoplanin (2), vancomycin (44), and methicillin (oxacillin) (30,44,49). Therefore, one possibility is that the B stress regulon is involved in antibiotic resistance, and likewise the lrg and cid operons may also play a role in this response.…”

Section: Discussionmentioning

confidence: 99%

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Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

et al. 2004

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The Staphylococcus aureus lrg and cid loci are homologous operons that have been shown to regulate murein hydrolase activity and affect sensitivity to penicillin. Although the mode of action of these operons has not been demonstrated, a model based on the similarities of the lrgA and cidA gene products to the bacteriophage holin family of proteins has been proposed. In this study, the transcription organization and regulation of these operons were examined by Northern blot analyses. Unexpectedly, cidB and a gene located immediately downstream, designated cidC, were found to be cotranscribed on a 2.7-kb transcript. Maximal cidBC transcription occurred during early exponential growth, and high-level transcription of cidBC was dependent on the rsbUmediated activation of the alternative sigma factor B ( B ). In contrast, lrgAB transcription in stationary phase was negatively regulated by B . Although cidABC transcription was not detected by Northern blot analysis, reverse transcriptase PCR revealed that these genes are also cotranscribed as a single RNA message in early exponential growth. Primer extension analysis revealed the presence of two cidBC transcription start sites, but no apparent B -dependent promoter consensus sequence was identified in these regions. The rsbU gene was also shown to have a positive impact on murein hydrolase activity but a negligible effect on sensitivity to penicillin-induced killing. These results suggest that the lrgAB and cidBC genes may be part of the S. aureus B -controlled stress regulon.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

et al. 2004

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“…B of S. aureus was demonstrated to influence the expression of a variety of genes (6,26,33,43,78,79), including virulence factors (23,27,34,38,43,50,51,52,62,78,79) and regulatory elements (5,6,21,26,34,47,60,66). Moreover, it affects methicillin and glycopeptide resistance (4,56,65,74), biofilm production (58), and internalization into endothelial cells (51) and is involved in the general stress response (12,25,27,34,42,43). Although B interferes with the expression of virulence determinants, its effect in animal models seemed not apparent (12,23,34,52) except in a murine model of septic arthritis (35).…”

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confidence: 99%

Molecular Analysis and Organization of the σ ^B Operon in Staphylococcus aureus

et al. 2005

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The alternative sigma factor B of Staphylococcus aureus controls the expression of a variety of genes, including virulence determinants and global regulators. Genetic manipulations and transcriptional start point (TSP) analyses showed that the sigB operon is transcribed from at least two differentially controlled promoters: a putative A -dependent promoter, termed sigB p1 , giving rise to a 3.6-kb transcript covering sa2059-sa2058-rsbU-rsbV-rsbW-sigB, and a B -dependent promoter, sigB p3 , initiating a 1.6-kb transcript covering rsbV-rsbWsigB. TSP and promoter-reporter gene fusion experiments indicated that a third promoter, tentatively termed sigB p2 and proposed to lead to a 2.5-kb transcript, including rsbU-rsbV-rsbW-sigB, might govern the expression of the sigB operon. Environmental stresses, such as heat shock and salt stress, induced a rapid response within minutes from promoters sigB p1 and sigB p3 . In vitro, the sigB p1 promoter was active in the early growth stages, while the sigB p2 and sigB p3 promoters produced transcripts throughout the growth cycle, with sigB p3 peaking around the transition state between exponential growth and stationary phase. The amount of sigB transcripts, however, did not reflect the concentration of B measured in cell extracts, which remained constant over the entire growth cycle. In a guinea pig cage model of infection, sigB transcripts were as abundant 2 and 8 days postinoculation as values found in vitro, demonstrating that sigB is indeed transcribed during the course of infection. Physical interactions between staphylococcal RsbU-RsbV, RsbV-RsbW, and RsbW-B were inferred from a yeast (Saccharomyces cerevisiae) two-hybrid approach, indicating the presence of a partner-switching mechanism in the B activation cascade similar to that of Bacillus subtilis. The finding that overexpression of RsbU was sufficient to trigger an immediate and strong activation of B , however, signals a relevant difference in the regulation of B activation between B. subtilis and S. aureus in the cascade upstream of RsbU.Staphylococcus aureus is one of the leading causes for nosocomial-and community-acquired infections (11,46). Its capacity to cause a wide spectrum of diseases and to survive in unfavorable conditions is due to a network of global regulatory elements enabling it to rapidly sense changes and to respond appropriately. These elements comprise two-component regulatory systems, including the agr locus, the SarA protein family, and alternative factors (reviewed in reference 16 and references within).Computational analysis of the published staphylococcal genomes suggests that S. aureus harbors only two alternative sigma factors, B and H (45). B of S. aureus was demonstrated to influence the expression of a variety of genes (6,26,33,43,78,79), including virulence factors (23,27,34,38,43,50,51,52,62,78,79) and regulatory elements (5,6,21,26,34,47,60,66). Moreover, it affects methicillin and glycopeptide resistance (4,56,65,74), biofilm production (58), and internalization into endothelial ce...

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“…The genomic DNAs were digested by EcoRI and NdeI, and probed with the sigB specific probe. and arbekacin) or in other phenotypes, such as carotenoid accumulation or survival after the stationary phase (data not shown), which are known to be altered by abolishing the SigB activity (Kullik et al, 1998;Singh et al, 2003;Wu et al, 1996). These results suggested that the effect of SigB amino acid substitutions is specific to certain stress tolerance.…”

Section: Amino Acid Substitutions In Sigb Are Essential To Maintain Tmentioning

confidence: 87%

“…It has been established that sigB is essential to achieve high-level b-lactam resistance in many strains (Singh et al, 2003;Wu et al, 1996). In addition, the quantitative effect of SigB was also postulated in N315; overexpression of sigB using a pRIT5H high 268 INOSE et al Vol.…”

Section: Effects Of the Substitutions On Phenotypesmentioning

confidence: 99%

Genetic characterization of the natural SigB variants found in clinical isolates of Staphylococcus aureus

Inose

Takeshita

Hidaka

et al. 2006

J. Gen. Appl. Microbiol.

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Impact of sigB mutation on Staphylococcus aureus oxacillin and vancomycin resistance varies with parental background and method of assessment

Cited by 56 publications

References 26 publications

Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

Molecular Analysis and Organization of the σ ^B Operon in Staphylococcus aureus

Genetic characterization of the natural SigB variants found in clinical isolates of Staphylococcus aureus

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Impact of sigB mutation on Staphylococcus aureus oxacillin and vancomycin resistance varies with parental background and method of assessment

Cited by 56 publications

References 26 publications

Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

Transcription of the Staphylococcus aureus cid and lrg Murein Hydrolase Regulators Is Affected by Sigma Factor B

Molecular Analysis and Organization of the σ B Operon in Staphylococcus aureus

Genetic characterization of the natural SigB variants found in clinical isolates of Staphylococcus aureus

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Molecular Analysis and Organization of the σ ^B Operon in Staphylococcus aureus