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Genetic instability of the global regulator agr explains the phenotype of the xpr mutation in Staphylococcus aureus KSI9051.

ABSTRACT: Staphylococcus aureus KSI9051 has a complex mutation that was associated with the aberrant expression of cell surface and extracellular proteins (M. S. Smeltzer, M. E. Hart, and J. J. Iandolo, J. Bacteriol. 61:919-925, 1993). This mutation was named xpr, although no specific gene was identified. Here this mutation is referred to as Delta1058::Tn551. In this study, we show that in strain KSI9051, the Delta1058::Tn551 mutation occurred coincidentally with a frameshift in agrC that is expected to truncate the sensor component of the known staphylococcal global regulatory locus agr. Remarkably, pleiotropic mutations affecting cell surface and extracellular proteins are generated at frequencies approaching 50% upon the transduction of erythromycin resistance (Emr) encoded by Delta1058::Tn551 from S. aureus KSI905 back to its parental strain, S6C. Three independent isolates created in the manner of KSI9051 contained mutations within agrC. Each isolate had different mutations, suggesting that the transduction of Emr encoded by Delta1058::Tn551 affects the stability of agrC in S6C. In similar experiments with strains from an S. aureus 8325 genetic background, a mutant AgrC phenotype could not be isolated, implying that strain S6 has aberrant genetic behavior. A comparison of the nucleotide sequences of AgrC from several strains revealed seven errors in the GenBank entry for agr (X52543); these data were confirmed with plasmid pRN6650, the original wild-type clone of agr.

SUBMITTER: McNamara PJ

PROVIDER: S-EPMC107210 | biostudies-literature | 1998 May

REPOSITORIES: biostudies-literature

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Genetic instability of the global regulator agr explains the phenotype of the xpr mutation in Staphylococcus aureus KSI9051.

McNamara P J PJ Iandolo J J JJ

Journal of bacteriology 19980501 10

Staphylococcus aureus KSI9051 has a complex mutation that was associated with the aberrant expression of cell surface and extracellular proteins (M. S. Smeltzer, M. E. Hart, and J. J. Iandolo, J. Bacteriol. 61:919-925, 1993). This mutation was named xpr, although no specific gene was identified. Here this mutation is referred to as Delta1058::Tn551. In this study, we show that in strain KSI9051, the Delta1058::Tn551 mutation occurred coincidentally with a frameshift in agrC that is expected to t ...[more]

PMID: 9573143

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Project description:BackgroundStaphylococcus aureus (S. aureus) with accessory gene regulator (agr) dysfunction occurs in health care settings. This study evaluated the prevalence and the molecular and drug resistance characteristics of S. aureus with dysfunctional agr in a pediatric population in Beijing, China.ResultsA total of 269 nonduplicate S. aureus clinical isolates were isolated from Beijing Children's Hospital, including 211 methicillin-resistant S. aureus (MRSA) from September 2010-2017 and 58 methicillin-sensitive S. aureus (MSSA) from February 2016-2017. Only 8 MRSA and 2 MSSA isolates were identified as agr dysfunction, and the overall prevalence rate was 3.7%. For MRSA isolates, ST59-SCCmec IV and ST239-SCCmec III were the most common clones, and the prevalence rate of agr dysfunction in ST239-SCCmec III isolates (17.39%) was significantly higher than in ST59-SCCmec IV (1.69%) and other genotype strains (P = 0.006). Among the agr dysfunctional isolates, only one MRSA ST59 isolate and one MSSA ST22 isolate harbored pvl. No significant difference was detected between agr dysfunction and agr functional isolates regarding the biofilm formation ability (P = 0.4972); however, 9/10 agr dysfunctional isolates could effectuate strong biofilm formation and multidrug resistance. Among MRSA, the non-susceptibility rates to ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole were significantly higher in agr dysfunctional isolates than in isolates with functional agr (P < 0.05). Two isolates belonging to ST239 had no mutations in agr locus, but a synonymous mutation was found in agrA in another ST239 isolate. The inactivating mutations were detected in other seven agr dysfunctional isolates. The variants were characterized by non-synonymous changes (n = 5) and frameshift mutations (insertions, n = 2), which mainly occurred in agrC and agrA.ConclusionsThe results showed that agr dysfunctional S. aureus was not common in Chinese children, and ST59-SCCmec IV was associated with lower prevalence of agr dysfunction as compared to ST239-SCCmec III isolates. The agr dysfunctional isolates were healthcare-associated, multidrug resistant and form strong biofilm, which suggested that agr dysfunction might offer potential advantages for S. aureus to survive in a medical environment.

Dataset Information

Genetic instability of the global regulator agr explains the phenotype of the xpr mutation in Staphylococcus aureus KSI9051.

Publications

Genetic instability of the global regulator agr explains the phenotype of the xpr mutation in Staphylococcus aureus KSI9051.

Similar Datasets

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