Evolving MRSA: High-level β-lactam resistance in Staphylococcus aureus is associated with RNA Polymerase alterations and fine tuning of gene expression
Fig 2
Identification of rpoB/C mutations and reconstitution of 8325–4 and Newman expressing single copy mecA.
A) Schematic representation of the genomic region of the rpoB/C operon, and downstream genes. Amino acid substitutions identified in resistant derivatives of lysA::pmecA (SJF4996) are indicated with a red box representing highly resistant mutants with oxacillin MIC of ≥256 μg/ml and a grey box representing intermediate resistant mutants with oxacillin MIC of up to 16 μg/ml. B) Chromosomal integration of mecA at lysA locus in 8325–4 did not result in high-level oxacillin resistance. C) The introduction of lysA::pmecA and rpoB-H929Q kan of SJF5046 into Newman resulted in the development of high-level resistance. Oxacillin susceptibility of Newman lysA::pmecA rpoB-H929Q kan (SJF5050) and its parental strain Newman were compared using Etest.