Participation of the arcRACME protein in self-activation of the arc operon located in the arginine catabolism mobile element in pandemic clone USA300.

Zayda Lorena Corredor Rozo,Javier Escobar-Pérez,Natasha Vanegas Gómez,Ricaurte Alejandro Márquez-Ortiz,Betsy Esperanza Castro

doi:10.1590/0074-02760160424

Zayda Lorena Corredor Rozo, Javier Escobar-Pérez + Show 3 more

Open Access

https://doi.org/10.1590/0074-02760160424

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Abstract

ABSTRACT Staphylococcus aureus pandemic clone USA300 has, in addition to its constitutive arginine catabolism (arc) gene cluster, an arginine catabolism mobile element (ACME) carrying another such cluster, which gives this clone advantages in colonisation and infection. Gene arcR, which encodes an oxygen-sensitive transcriptional regulator, is inside ACME and downstream of the constitutive arc gene cluster, and this situation may have an impact on its activation. Different relative expression behaviours are proven here for arcR ACME and the arc ACME operon compared to the constitutive ones. We also show that the artificially expressed recombinant ArcRACME protein binds to the promoter region of the arc ACME operon; this mechanism can be related to a positive feedback model, which may be responsible for increased anaerobic survival of the USA300 clone during infection-related processes.

Highlights

Staphylococcus aureus USA300 clone is characterised by its resistance to most β-lactam antibiotics, virulence, global spread, and association with invasive diseases (Diep et al 2006)
The fragment indicated by an asterisk (*) is the promoter probe that contains the Crp-binding motif TGTGA-N6-TCACA. (B) Co-transcription of arcRACME with the other genes of the argenine transcriptional regulator gene (arcR) in the arginine catabolism mobile element (arcACME) operon in strain USA300 under anaerobic conditions, as determined by polymerase chain reaction (PCR) using total cDNA as a template and primers 1 and 2 from panel A
Lane 3 is the same PCR analysis of RNA as a control to rule out DNA remnants. (C) Relative transcription levels of genes arcRACME, arcCACME, arcRcons, and arcCcons genes during anaerobiosis in the stationary phase (20 h; results are expressed as the mean of two different experiments)

Summary

Introduction

Staphylococcus aureus USA300 clone is characterised by its resistance to most β-lactam antibiotics, virulence, global spread, and association with invasive diseases (Diep et al 2006). Quantification of relative expression of constitutive arcR and arcC genes (arcCcons and arcRcons) and the genes from ACME (arcRACME, arcCACME) was determined by quantitative PCR (qPCR) to treated (50 mM arginine) and untreated (without arginine) S. aureus USA300_FPR3757 and NCTC8325 strains (as a control of basal expression of the constitutive genes) strains in TSB cultures (Supplementary data, Tables I-II and methods).

Results

Conclusion