The putA gene of Agrobacterium tumefaciens is transcriptionally activated in response to proline by an Lrp-like protein and is not autoregulated

Molecular Microbiology
K Cho, S C Winans

Abstract

The Agrobacterium tumefaciens putA gene, which encodes proline dehydrogenase, is transcriptionally induced by exogenous proline. In contrast to the putA genes of enteric bacteria, the A. tumefaciens putA gene is not regulated by the PutA protein, as the putA promoter remained strongly proline inducible in strains lacking PutA. A putA null mutation increased the expression of the putA promoter under a variety of conditions. However, this mutation is predicted to increase the cytoplasmic concentration of proline, and this alone probably accounts for its effects on putA expression. The putA promoter was also strongly induced by valine, and the putA genotype did not affect expression by this gratuitous inducer. An open reading frame (ORF) encoding an Lrp-like protein was found transcribed divergently from putA. Disruption of this ORF, designated putR, abolished induction of the putA promoter by proline or valine. In addition to activating putA, PutR also repressed its own transcription, and this autorepression was only slightly affected by exogenous proline. The transcription start sites for the putA and putR genes are separated by 64 nucleotides, suggesting that PutR could regulate both promoters by binding to a single operator.

Citations

Feb 3, 2006·Journal of Bacteriology·Navasona Krishnan, Donald F Becker
Feb 2, 2008·Biological & Pharmaceutical Bulletin·Tsuyoshi KawashimaMasashi Suzuki
Feb 21, 2004·Proceedings of the National Academy of Sciences of the United States of America·Hideaki KoikeMasashi Suzuki
Mar 8, 2014·Critical Reviews in Microbiology·Michael Frederick Dunn
Oct 4, 2018·Scientific Reports·Annabelle MouammineJustine Collier
Apr 11, 2018·Frontiers in Microbiology·Ruiping ZhengZhihui Cheng
Sep 1, 1997·Journal of Bacteriology·B R BelitskyC Von Wachenfeldt

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