Expression of itaT toxin gene is enhanced under aminoglycoside stress in Escherichia coli harbouring aac(6′)Ib

Abstract

Toxin-antitoxin complex play a major role in dormant state and is compensated by their cognate antitoxin under normal growth phase. Toxins are released which impede the cellular processes by several system under antibiotics stress. Type II toxins reside at the GCN5 N-acetyltransferases (GNAT) subfamily to which the target was shown to be aminoacyl-tRNA. This study aims to observe the transcriptional expression of itaTR and ataTR under aminoglycoside stress. Clinical isolates, cured mutants (treated with SDS 2%,4%,6%,8% and 10%) as well as a clone of aac(6′)-Ib, were used for the study. Transcriptional expression analysis of itaTR and ataTR genes were carried out under normal condition (without antibiotic) and with aminoglycoside stress (2 μg/ml and 4 μg/ml). It was observed that against exposure of gentamicin and amikacin, expression level of itaT was increased but reduced when antibiotics concentration was raised and vice versa as for itaR. In the case of ataT expression level was decreased under antibiotic stress but for ataR it was overexpressed significantly. This study investigated, for the first time, how toxin-antitoxin (itaTR and ataTR) systems counter against amikacin and gentamicin stress in Escherichia coli harbouring aac (6′)-Ib.