The expression of gyrI in E. coli strains in the exponential phase of growth

Background and Aim: The gyrI gene is one of the SOS regulon genes, encoding GyrI protein. This protein can inhibit the activity of DNA gyrase. This enzyme plays an important role in the replication of bacteria and its inhibition by fluoroquinolones, such as ciprofloxacin causes DNA double-strand breaks and eventually cell death. Double-strand breaks in DNA induce the SOS response. The aim of this study was to measure the expression of gyrI gene in E. coli strains.Methods: To investigate the expression of gyrI, the cellular RNA was first extracted in exponential phase of growth and after cDNA synthesis; the relative expression of genes was measured by Real Time PCR.Results: The results showed significantly increased expression of gyrI during the exponential phase of growth in ciproflucacin-resistant mutant strain compared to wild type strain (P <۰.۰۵).Conclusion: According to this result, we suggest an indirect role of the SOS system on the activity of DNA gyrase.

Keywords:

Fluoroquinolone , DNA gyrase , E. coli , GyrI , Real Time PCR