Ion (203, 502). The expression of gdhA in E. coli is also repressed by Nac (503). However, whether the mechanism of repression of gdhA in E. coli by NacE is similar to that of NacK remains to be determined. The expression of gdhA may also be affected by the global transcriptional regulator FNR during growth in high-osmolarity media, but the underlying mechanism is unknown (494). Finally, gdhA tran