Daptomycin tolerance in the Staphylococcus aureus pitA6 mutant is due to upregulation of the dlt-operon
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ABSTRACT: It is very important to understand the mechanisms how bacteria become tolerant towards antibiotics during clinical therapy. In a previous study we showed that increased daptomycin (DAP) tolerance of Staphylococcus aureus was due to a point mutation in pitA (inorganic phosphate transporter) that led to intracellular accumulation of both inorganic phosphate (Pi) and polyphosphate (polyP). DAP tolerance in that pitA6 mutant differs from classical resistance mechanisms as there was no increase in minimal inhibitory concentration (MIC). In this study we demonstrate that DAP tolerance in the pitA6 mutant is not triggered by the accumulation of polyP. Transcriptome analysis revealed that about 234 genes were at least 2.0-fold differently expressed in the mutant. Particularly, genes involved in protein biosynthesis, carbohydrate and lipid metabolism as well as in replication and maintenance of DNA were downregulated. However, the most important change was the upregulation of the dlt-operon, which is induced by the accumulation of intracellular Pi. The GraXRS system, known as activator of both dlt and mprF, as well as surface charge, cell wall thickness or the content of wall teichoic acids (WTA) are not involved in DAP tolerance in the pitA6 mutant. In conclusion the DAP tolerance in the pitA6 mutant is due to an upregulation of the dlt-operon triggered directly or indirectly by the accumulation of Pi. WT strain HG003 and its pitA mutant were used to compare transcriptomic changes after 6 or 8 hours of growth in suspension in TSB medium
ORGANISM(S): Staphylococcus aureus
SUBMITTER: FRANCOIS Patrice
PROVIDER: E-GEOD-77069 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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