Dual inducer signal recognition by an Mlc homologue.

The Mlc transcription factor in Escherichia coli controls the expression of the phosphotransferase system genes implicated in the transport of glucose into the cell. Transport of glucose derepresses Mlc-repressed genes by provoking the sequestration of Mlc to the membrane, via an interaction with the dephosphorylated EIIB domain of the glucose transporter, PtsG. NagC, a paralogue of Mlc in E.

Operator recognition by the ROK transcription factor family members, NagC and Mlc.

NagC and Mlc, paralogous members of the ROK family of proteins with almost identical helix-turn-helix DNA binding motifs, specifically regulate genes for transport and utilization of N-acetylglucosamine and glucose. We previously showed that two amino acids in a linker region outside the canonical helix-turn-helix motif are responsible for Mlc site specificity. In this work we identify four amino acids in the linker, which are required for recognition of NagC targets.

The linker sequence, joining the DNA-binding domain of the homologous transcription factors, Mlc and NagC, to the rest of the protein, determines the specificity of their DNA target recognition in Escherichia coli.

Protein-DNA recognition is fundamental to transcriptional regulation. Transcription factors must be capable of locating their specific sites situated throughout the genome and distinguishing them from related sites. Mlc and NagC control uptake and use of the sugars, glucose and N-acetylglucosamine.

Activation of 5'-3' exoribonuclease Xrn1 by cofactor Dcs1 is essential for mitochondrial function in yeast.

The scavenger decapping enzyme Dcs1 has been shown to facilitate the activity of the cytoplasmic 5'-3' exoribonuclease Xrn1 in eukaryotes. Dcs1 has also been shown to be required for growth in glycerol medium. We therefore wondered whether the capacity to activate RNA degradation could account for its requirement for growth on this carbon source.

Polyadenylation of a functional mRNA controls gene expression in Escherichia coli.

Although usually implicated in the stabilization of mRNAs in eukaryotes, polyadenylation was initially shown to destabilize RNA in bacteria. All the data are consistent with polyadenylation being part of a quality control process targeting folded RNA fragments and non-functional RNA molecules to degradation. We report here an example in Escherichia coli, where polyadenylation directly controls the level of expression of a gene by modulating the stability of a functional transcript.