کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5673786 | 1593686 | 2017 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: The 95ÎG mutation in the 5â²untranslated region of the norA gene increases efflux activity in Staphylococcus epidermidis isolates The 95ÎG mutation in the 5â²untranslated region of the norA gene increases efflux activity in Staphylococcus epidermidis isolates](/preview/png/5673786.png)
- The 5â²UTR effect of norA gene over the efflux was studied in S. epidermidis.
- Isolates had a high efflux activity (HEA) phenotypic for ethidium bromide (EtBr).
- Isolates with HEA had the 5â²UTR 95ÎG mutation and high levels of norA expression.
- The 95ÎG mutation produces changes in the Shine-Dalgarno region.
- The 5â²UTR 95ÎG mutation of norA gene is involved in the EtBr efflux.
In the Staphylococcus aureus ATCC25923 strain, the flqB mutation in the 5â²untranslated region (5â²UTR) of the norA gene causes increased norA mRNA expression and high efflux activity (HEA). The involvement of the norA gene 5â²UTR in HEA has not been explored in S. epidermidis; therefore, we examined the function of this region in S. epidermidis clinical isolates. The selection of isolates with HEA was performed based on ethidium bromide (EtBr) MIC values and efflux efficiency (EF) using the semi-automated fluorometric method. The function of the 5â²UTR was studied by quantifying the levels of norA expression (RT-qPCR) and by identifying 5â²UTR mutations by sequence analysis. Only 10 isolates from a total of 165 (6.1%) had HEA (EtBr MIC = 300 μg/ml and EF ranged from 48.4 to 97.2%). Eight of 10 isolates with HEA had the 5â²UTR 95ÎG mutation. Isolates carrying the 95ÎG mutation had higher levels of norA expression compared with those that did not. To corroborate that the 95ÎG mutation is involved in HEA, a strain adapted to EtBr was obtained in vitro. This strain also presented the 95ÎG mutation and had a high level of norA expression and EF, indicating that the 95ÎG mutation is important for the HEA phenotype. The 95ÎG mutation produces a different structure in the Shine-Dalgarno region, which may promote better translation of norA mRNA. To our knowledge, this is the first report to demonstrate the participation of the 5â²UTR 95ÎG mutation of the norA gene in the HEA phenotype of S. epidermidis isolates. Here, we propose that the efflux of EtBr is caused by an increment in the transcription and/or translation of the norA gene.
Journal: Microbial Pathogenesis - Volume 103, February 2017, Pages 139-148