MtfA (earlier known as YeeI) is a transcription factor A that binds Mlc (make large colonies), itself a repressor of glucose and hence a protein important in regulation of the phosphoenolpyruvate:glucose-phosphotransferase (ptsG) system, the major glucose transporter in E.coli. Mlc is a repressor of ptsG, and MtfA is found to bind and inactivate Mlc with high affinity. The membrane-bound protein EIICBGlc encoded by the ptsG gene is the major glucose transporter in Escherichia coli. MtfA is found to be a glucose-regulated peptidase, whose activity is regulated by binding to Mlc available in the cytoplasm, which in turn has been released from EIICBGlc during times when no glucose is taken up. A physiologically relevant target for this peptidase is not yet known.