N-acetylgalatosamine-Mediated Regulation of the Operon by AgaR in .

Here, we analyze the transcriptomic response of D39 to N-acetylgalactosamine (NAGa). Transcriptome comparison of D39 grown in NAGaM17 (0.5% NAGa + M17) to that grown in GM17 (0.5% Glucose + M17) revealed the elevated expression of various carbon metabolic genes/operons, including a PTS operon (denoted here as the operon), which is putatively involved in NAGa transport and utilization, in the presence of NAGa. We further studied the role of a GntR-family transcriptional regulator (denoted here as AgaR) in the regulation of operon. Our transcriptome and RT-PCR data suggest the role of AgaR as a transcriptional repressor of the operon. We predicted a 20-bp operator site of AagR (5'-ATAATTAATATAACAACAAA-3') in the promoter region of the operon (P), which was further verified by mutating the AgaR operator site in the respective promoter. The role of CcpA in the additional regulation of the operon was elucidated by further transcriptome analyses and confirmed by quantitative RT-PCR.