Transcriptional cross-regulation between Gram-negative and gram-positive bacteria, demonstrated using ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum.
The protein-gene pairs ArgP-argO of Escherichia coli and LysG-lysE of Corynebacterium glutamicum are orthologous, with the first member of each pair being a LysR-type transcriptional regulator and the second its target gene encoding a basic amino acid exporter. Whereas LysE is an exporter of arginine (Arg) and lysine (Lys) whose expression is induced by Arg, Lys, or histidine (His), ArgO exports Arg alone, and its expression is activated by Arg but not Lys or His. We have now reconstituted in E. coli the activation of lysE by LysG in the presence of its coeffectors and have shown that neither ArgP nor LysG can regulate expression of the noncognate orthologous target. Of several ArgP-dominant (ArgP(d)) variants that confer elevated Arg-independent argO expression, some (ArgP(d)-P274S, -S94L, and, to a lesser extent, -P108S) activated lysE expression in E. coli. However, the individual activating effects of LysG and ArgP(d) on lysE were mutually extinguished when both proteins were coexpressed in Arg- or His-supplemented cultures. In comparison with native ArgP, the active ArgP(d) variants exhibited higher affinity of binding to the lysE regulatory region and less DNA bending at both argO and lysE. We conclude that the transcription factor LysG from a Gram-positive bacterium, C. glutamicum, is able to engage appropriately with the RNA polymerase from a Gram-negative bacterium, E. coli, for activation of its cognate target lysE in vivo and that single-amino-acid-substitution variants of ArgP can also activate the distantly orthologous target lysE, but by a subtly different mechanism that renders them noninterchangeable with LysG.
Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.
Carmelita N
CN
Marbaniang
J
J
Gowrishankar
D026905:Amino Acid Transport Systems / Q000096:biosynthesis* / Q000235:genetics; D026923:Amino Acid Transport Systems, Basic / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D048230:Corynebacterium glutamicum / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D060847:Metabolic Engineering; D033902:Periplasmic Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D011995:Recombination, Genetic; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D026905:Amino Acid Transport Systems; D026923:Amino Acid Transport Systems, Basic; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C104616:LysE protein, Corynebacterium glutamicum; C438905:LysG protein, Corynebacterium glutamicum; D033902:Periplasmic Binding Proteins; C035727:arginine-ornithine periplasmic transport protein, bacteria; C068863:argP protein, E coli