PMID:21494631

Citation	Liang, X, Hall, JW, Yang, J, Yan, M, Doll, K, Bey, R and Ji, Y (2011) Identification of single nucleotide polymorphisms associated with hyperproduction of alpha-toxin in Staphylococcus aureus. PLoS ONE 6:e18428
Abstract	The virulence factor α-toxin (hla) is needed by Staphylococcus aureus in order to cause infections in both animals and humans. Although the complicated regulation of hla expression has been well studied in human S. aureus isolates, the mechanisms of of hla regulation in bovine S. aureus isolates remain undefined. In this study, we found that many bovine S. aureus isolates, including the RF122 strain, generate dramatic amounts of α-toxin in vitro compared with human clinical S. aureus isolates, including MRSA WCUH29 and MRSA USA300. To elucidate potential regulatory mechanisms, we analyzed the hla promoter regions and identified predominant single nucleotide polymorphisms (SNPs) at positions -376, -483, and -484 from the start codon in α-toxin hyper-producing isolates. Using site-directed mutagenesis and hla promoter-gfp-luxABCDE dual reporter approaches, we demonstrated that the SNPs contribute to the differential control of hla expression among bovine and human S. aureus isolates. Using a DNA affinity assay, gel-shift assays and a null mutant, we identified and revealed that an hla positive regulator, SarZ, contributes to the involvement of the SNPs in mediating hla expression. In addition, we found that the bovine S. aureus isolate RF122 exhibits higher transcription levels of hla positive regulators, including agrA, saeR, arlR and sarZ, but a lower expression level of hla repressor rot compared to the human S. aureus isolate WCUH29. Our results indicate α-toxin hyperproduction in bovine S. aureus is a multifactorial process, influenced at both the genomic and transcriptional levels. Moreover, the identification of predominant SNPs in the hla promoter region may provide a novel method for genotyping the S. aureus isolates.
Links	PubMed PMC3072997 Online version:10.1371/journal.pone.0018428
Keywords	Amino Acid Sequence; Animals; Bacterial Toxins/biosynthesis; Bacterial Toxins/chemistry; Bacterial Toxins/genetics; Cattle; Electrophoresis, Polyacrylamide Gel; Female; Gene Expression Regulation, Bacterial; Genes, Bacterial; Hemolysin Proteins/biosynthesis; Hemolysin Proteins/chemistry; Hemolysin Proteins/genetics; Hemolysis; Humans; Mastitis, Bovine/microbiology; Molecular Sequence Data; Mutation/genetics; Polymorphism, Single Nucleotide/genetics; Promoter Regions, Genetic/genetics; Staphylococcus aureus/genetics; Staphylococcus aureus/isolation & purification; Staphylococcus aureus/metabolism; Transcription, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STAAB:SARZ		GO:0006355: regulation of transcription, DNA-dependent	ECO:0000270:		P		Results Paragraph: SarZ is associated with the SNPs in the regulation of hyperproduction of α-toxin	complete CACAO 3407

References

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