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Analysis of a Cell Wall Mutant Highlights Rho-Dependent Genome Amplification Events in Staphylococcus aureus
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Resumo(s)
In a study of antibiotic resistance in Staphylococcus aureus, specific cell wall mutants were previously generated for the peptidoglycan biosynthesis gene murF, by the insertion of an integrative plasmid. A collection of 30 independent mutants was obtained, and all harbored a variable number of copies of the inserted plasmid, arranged in tandem in the chromosome. Of the 30 mutants, only 3, F9, F20 and F26, with a lower number of plasmid copies, showed an altered peptidoglycan structure, lower resistance to β-lactams and a different loss-of-function mutation in rho gene, that encodes a transcription termination factor. The rho mutations were found to correlate with the level of oxacillin resistance, since genetic complementation with rho gene reestablished the resistance and cell wall parental profile in F9, F20 and F26 strains. Furthermore, complementation with rho resulted in the amplification of the number of plasmid tandem repeats, suggesting that Rho enabled events of recombination that favored a rearrangement in the chromosome in the region of the impaired murF gene. Although the full mechanism of reversion of the cell wall damage was not fully elucidated, we showed that Rho is involved in the recombination process that mediates the tandem amplification of exogeneous DNA fragments inserted into the chromosome
Descrição
This work was financed by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy - i4HB. This work was also supported by FCT through Projects LISBOA-01-0145-FEDER007660 (Microbiologia Molecular, Estrutural e Celular); and by ONEIDA project (LISBOA-01-0145-FEDER-016417) co-funded by FEEI—“Fundos Europeus Estruturais e de Investimento” from “Programa Operacional Regional Lisboa2020” and by national funds through FCT.
Palavras-chave
antimicrobial resistance cell wall DNA recombination methicillin resistant Staphylococcus aureu Rho termination of transcription factor Physiology Ecology General Immunology and Microbiology Genetics Microbiology (medical) Cell Biology Infectious Diseases