The prevalence and implications of single nucleotide polymorphisms in genes encoding the RNA polymerase of clinical isolates of Staphylococcus aureus.

Aishwarya Krishna,Sivaramesh Wigneshweraraj,Sharon J Peacock,Bing Liu

doi:10.1002/mbo3.1058

Abstract

Central to the regulation of bacterial gene expression is the multisubunit enzyme RNA polymerase (RNAP), which is responsible for catalyzing transcription. As all adaptive processes are underpinned by changes in gene expression, the RNAP can be considered the major mediator of any adaptive response in the bacterial cell. In bacterial pathogens, theoretically, single nucleotide polymorphisms (SNPs) in genes that encode subunits of the RNAP and associated factors could mediate adaptation and confer a selective advantage to cope with biotic and abiotic stresses. We investigated this possibility by undertaking a systematic survey of SNPs in genes encoding the RNAP and associated factors in a collection of 1,429 methicillin‐resistant Staphylococcus aureus (MRSA) clinical isolates. We present evidence for the existence of several, hitherto unreported, nonsynonymous SNPs in genes encoding the RNAP and associated factors of MRSA ST22 clinical isolates and propose that the acquisition of amino acid substitutions in the RNAP could represent an adaptive strategy that contributes to the pathogenic success of MRSA.

Highlights

In their natural environments, bacteria must survive a multitude of stresses and cope with repeated bouts of feast and famine
It is possible that the entire sequence type 22 (ST22) lineage contains single nucleotide polymorphisms (SNPs) that are not present in other S. aureus lineages from other types of infection, results revealed that 144 methicillin-resistant Staphylococcus aureus (MRSA) ST22 clinical isolates (~10% of the collection) harbored at least one SNP in genes encoding the core RNA polymerase (RNAP) subunits or the σ factors that were absent in the reference strain HO 5096 0412
The majority of SNPs in genes encoding the S. aureus σA-RNAP resulted in aa substitutions that appeared on the surface of the enzyme—in regions of the RNAP potentially involved in interactions with nucleic acids and/or regulatory factors (Figure 2)

Summary

Introduction

Bacteria must survive a multitude of stresses and cope with repeated bouts of feast and famine. It is possible that the entire ST22 lineage contains SNPs that are not present in other S. aureus lineages from other types of infection, results revealed that 144 MRSA ST22 clinical isolates (~10% of the collection) harbored at least one SNP in genes encoding the core RNAP subunits or the σ factors that were absent in the reference strain HO 5096 0412.

Results

Conclusion