Evolving MRSA: High-level β-lactam resistance in Staphylococcus aureus is associated with RNA Polymerase alterations and fine tuning of gene expression

Autor: Oliver T. Carnell, Nikolay Zenkin, William L. Kelley, Bohdan Bilyk, Jeffrey Green, Viralkumar V. Panchal, Simon J. Foster, Jamie K. Hobbs, Joshua A. F. Sutton, Hamed Mosaei, David P. Hornby, Caitlin Griffiths
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Penicillin binding proteins
Penicillin-Binding Proteins/genetics
Staphylococcus
Bacterial/genetics
Gene Expression
medicine.disease_cause
Pathology and Laboratory Medicine
Biochemistry
Polymerases
chemistry.chemical_compound
Antibiotics
RNA polymerase
Gene expression
Medicine and Health Sciences
Staphylococcus Aureus
Biology (General)
ddc:616
0303 health sciences
Antimicrobials
030302 biochemistry & molecular biology
Drugs
DNA-Directed RNA Polymerases
DNA-Directed RNA Polymerases/genetics
Beta-Lactam Resistance/genetics
3. Good health
Bacterial Pathogens
Anti-Bacterial Agents
Staphylococcus aureus
Medical Microbiology
Pathogens
Research Article
Methicillin-Resistant Staphylococcus aureus
Cell Physiology
QH301-705.5
Immunology
Biology
Microbiology
beta-Lactam Resistance
Anti-Bacterial Agents/pharmacology
Methicillin-Resistant Staphylococcus aureus/drug effects/genetics
03 medical and health sciences
Antibiotic resistance
Bacterial Proteins
Virology
Microbial Control
DNA-binding proteins
medicine
Genetics
Point Mutation
Penicillin-Binding Proteins
Molecular Biology
Gene
Microbial Pathogens
030304 developmental biology
Pharmacology
Bacteria
Bacterial Proteins/genetics
Organisms
Biology and Life Sciences
Proteins
Cell Biology
Gene Expression Regulation
Bacterial
RC581-607
biochemical phenomena
metabolism
and nutrition
rpoB
Methicillin-resistant Staphylococcus aureus
Cell Metabolism
chemistry
Gene Expression Regulation
Antibiotic Resistance
Mutation
Parasitology
Antimicrobial Resistance
Immunologic diseases. Allergy
Zdroj: PLoS Pathogens
PLOS Pathogens, Vol. 16, No 7 (2020) P. e1008672
PLoS Pathogens, Vol 16, Iss 7, p e1008672 (2020)
ISSN: 1553-7374
1553-7366
Popis: Most clinical MRSA (methicillin-resistant S. aureus) isolates exhibit low-level β-lactam resistance (oxacillin MIC 2–4 μg/ml) due to the acquisition of a novel penicillin binding protein (PBP2A), encoded by mecA. However, strains can evolve high-level resistance (oxacillin MIC ≥256 μg/ml) by an unknown mechanism. Here we have developed a robust system to explore the basis of the evolution of high-level resistance by inserting mecA into the chromosome of the methicillin-sensitive S. aureus SH1000. Low-level mecA-dependent oxacillin resistance was associated with increased expression of anaerobic respiratory and fermentative genes. High-level resistant derivatives had acquired mutations in either rpoB (RNA polymerase subunit β) or rpoC (RNA polymerase subunit β’) and these mutations were shown to be responsible for the observed resistance phenotype. Analysis of rpoB and rpoC mutants revealed decreased growth rates in the absence of antibiotic, and alterations to, transcription elongation. The rpoB and rpoC mutations resulted in decreased expression to parental levels, of anaerobic respiratory and fermentative genes and specific upregulation of 11 genes including mecA. There was however no direct correlation between resistance and the amount of PBP2A. A mutational analysis of the differentially expressed genes revealed that a member of the S. aureus Type VII secretion system is required for high level resistance. Interestingly, the genomes of two of the high level resistant evolved strains also contained missense mutations in this same locus. Finally, the set of genetically matched strains revealed that high level antibiotic resistance does not incur a significant fitness cost during pathogenesis. Our analysis demonstrates the complex interplay between antibiotic resistance mechanisms and core cell physiology, providing new insight into how such important resistance properties evolve.
Author summary Methicillin resistant Staphylococcus aureus (MRSA) places a great burden on human healthcare systems. Resistance is mediated by the acquisition of a non-native penicillin-binding protein 2A (PBP2A), encoded by mecA. MRSA strains are resistant to virtually all β-lactam antibiotics, and can shift from being low- to high-level resistant. Prior studies have revealed the involvement of components of the core genome in increased resistance, but the underlying mechanism is still unknown. In this study, we have found that increased resistance is associated with mutations in either rpoB (RNA polymerase subunit β) or rpoC (RNA polymerase subunit β’) resulting in slower growth and elevated levels of PBP2A. Furthermore, transcript profiling revealed that insertion of mecA triggered metabolic imbalance by altering anaerobic and fermentative gene expression, accompanied by low-level resistance whereas, acquisition of rpoB and rpoC mutations reversed gene expression to wild-type level and enabled cells to become highly-resistant. The mutations also affected RNA polymerase activity. A set of matched strains revealed that changes in antibiotic resistance levels do not have a significant cost in terms of pathogenic potential. Our study reveals a novel effect of mecA acquisition on central metabolism and sheds light on potential pathways essential for high-level resistance.
Databáze: OpenAIRE
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