Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most genes required for cysteine biosynthesis in Salmonella typhimurium and Escherichia coli are positively regulated by cysB, which encodes a transcriptional activator belonging to the LysR family of regulatory proteins. CysB protein binds just upstream of the -35 region of positively regulated promoters, where in the presence of inducer it facilitates formation of a transcription initiation complex. CysB protein also autoregulates its own synthesis by binding to the cysB promoter as a repressor. Cysteine down-regulates the pathway by inhibiting synthesis of O-acetylserine, a direct cysteine precursor and possibly an inducer of gene expression. O-Acetylserine spontaneously isomerizes to N-acetylserine, which is clearly an inducer. Sulphide and thiosulphate provide additional regulation by acting as anti-inducers. Inducer stimulates CysB protein binding to sites involved in positive regulation, and inhibits binding to the negatively autoregulated cysB promoter. For three sites with unknown function, binding is stimulated at one and inhibited at the other two.
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PMID:The molecular basis for positive regulation of cys promoters in Salmonella typhimurium and Escherichia coli. 143 53

Pseudomonas putida DS1 is able to utilize dimethyl sulfone as a sulfur source. Expression of the sfnFG operon responsible for dimethyl sulfone oxygenation is directly regulated by a sigma(54)-dependent transcriptional activator, SfnR, which is encoded within the sfnECR operon. We investigated the transcription mechanism for the sulfate starvation-induced expression of these sfn operons. Using an in vivo transcription assay and in vitro DNA-binding experiments, we revealed that SfnR negatively regulates the expression of sfnECR by binding to the downstream region of the transcription start point. Additionally, we demonstrated that a LysR-type transcriptional regulator, CysB, directly activates the expression of sfnECR by binding to its upstream region. CysB is a master regulator that controls the sulfate starvation response of the sfn operons, as is the case for the sulfonate utilization genes of Escherichia coli, although CysB(DS1) appeared to differ from that of E. coli CysB in terms of the effect of O-acetylserine on DNA-binding ability. Furthermore, we investigated what effector molecules repress the expression of sfnFG and sfnECR in vivo by using the disruptants of the sulfate assimilatory genes cysNC and cysI. The measurements of mRNA levels of the sfn operons in these gene disruptants suggested that the expression of sfnFG is repressed by sulfate itself while the expression of sfnECR is repressed by the downstream metabolites in the sulfate assimilatory pathway, such as sulfide and cysteine. These results indicate that SfnR plays a role independent of CysB in the sulfate starvation-induced expression of the sfn operons.
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PMID:Transcription factors CysB and SfnR constitute the hierarchical regulatory system for the sulfate starvation response in Pseudomonas putida. 1845 3