Dataset Information


The Fusidic acid Stimulon of Staphylococcus aureus

ABSTRACT: Genome-wide transcriptional profiling studies of the growth of bacteria with antimicrobial agents often reveals aspects of the drug-specific protective bacterial response. Fusidic acid is a steroid antimicrobial that inhibits protein synthesis by interfering with the release of elongation factor G (EF-G) after it has functioned in the translocation step. Two hundred and seventy two genes were both up- and down-regulated in a fusidic acid-susceptible strain of Staphylococcus aureus following challenge with 2 mg/L-1 fusidic acid for 15 min. Many genes altered by fusidic acid challenge are associated with protein synthesis such as fusA, which encodes EF-G which was up-regulated following exposure to the drug. The Staphylococcus microarray meta-database which curates and compares S. aureus transcriptome data revealed that the fusidic acid stimulon has the greatest overlap with the S. aureus cold shock- and stringent-responses. Six out of 9 autolysin genes making up the two component YycFG regulon (ssaA1-ssaA4, isaA and sceD) were also upregulated by fusidic acid; as were a carboxylesterase (est) and two putative Emr-Qac-like multidrug efflux pumps (emr-qac1 and emr-qac2). Genes down-regulated by fusidic acid induction encode a putative secreted acid phosphatase (sapS) and a number of protease genes (yjbG1, yjbG2, htrA1 and htrA2). Transcriptional analysis in conjunction with mutant fusidic acid susceptibility experiments revealed that th45 e virulence gene regulatory agr operon, a YycFG controlled peptidoglycan hydrolase gene isaA and the proteases htrA1 and htrA2 are required for the expression of wild-type levels of fusidic acid susceptibility. Overall design: S. aureus pangenome microarrays were utilized to determine transcriptome alterations occurring in S. aureus grown in the presence of fusidic acid. Total bacterial RNA was isolated as previously described from S. aureus strain SH1000 grown in Muellar-Hinton broth to an OD580nm of 1.0 (37°C, 200 rpm) and then induced with 2 mg/L-1 fusidic acid for 15 min. This RNA and RNA isolated from untreated SH1000 cultures were then converted to fluorescently-labeled cDNA and hybridized to S. aureus microarrays version 4 (NIAID's Pathogen Functional Genomics Resource Center). The Staphylococcus aureus microarray meta-database (SAMMD) curates data from various microarray experiments and allows for the comparison of microarray data obtained from different protocols and experiments. SAMMD was used to analyze the transcriptome generated from SH1000 grown in the presence of fusidic acid. Real-time PCR to confirm microarray data was performed. Following growth of SH1000 with and without fusidic acid addition at various time points, the cultures were serial diluted with fresh MHB, inoculated onto Muellar Hinton agar and the total surviving CFUs/ml were determined after 24 h.

INSTRUMENT(S): JCVI PFGRC Staphylococcus aureus version 4 array

SUBMITTER: John E Gustafson Arunachalam Muthaiyan  

PROVIDER: GSE12210 | GEO | 2008-08-25



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The fusidic acid stimulon of Staphylococcus aureus.

Delgado Alejandro A   Zaman Shahrear S   Muthaiyan Arunachalam A   Nagarajan Vijayaraj V   Elasri Mohamed O MO   Wilkinson Brian J BJ   Gustafson John E JE  

The Journal of antimicrobial chemotherapy 20080910 6

Fusidic acid interferes with the release of elongation factor G (EF-G) after the translocation step of protein synthesis. The objective of this study was to characterize the fusidic acid stimulon of a fusidic acid-susceptible strain of Staphylococcus aureus (SH1000).S. aureus microarrays and real-time PCR determined transcriptome alterations occurring in SH1000 grown with fusidic acid. The Staphylococcus aureus microarray meta-database (SAMMD) compared and contrasted the SH1000 fusidic stimulon  ...[more]

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