Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The bet regulon allows Escherichia coli to synthesize the osmoprotectant glycine betaine from choline. It comprises a regulatory gene, betI, and three structural genes: betT (choline porter), betA (choline dehydrogenase), and betB (betaine aldehyde dehydrogenase). The bet genes are regulated by oxygen, choline, and osmotic stress. Primer extension analysis identified two partially overlapping promoters which were responsible for the divergent expression of the betT and betIBA transcripts. The transcripts were initiated 61 bp apart. Regulation of the promoters was investigated by using cat (chloramphenicol acetyltransferase) and lacZ (beta-galactosidase) operon fusions. Mutation of betI on plasmid F'2 revealed that BetI is a repressor which regulates both promoters simultaneously in response to the inducer choline. Both promoters remained inducible by osmotic stress in a betI mutant background. On the basis of experiments with hns and hns rpoS mutants, we conclude that osmoregulation of the bet promoters was hns independent. The bet promoters were repressed by ArcA under anaerobic growth conditions. An 89-bp promoter fragment, as well as all larger fragments tested, which included both transcriptional start points, displayed osmotic induction and BetI-dependent choline regulation when linked with a cat reporter gene on plasmid pKK232-8. Flanking DNA, presumably on the betT side of the promoter region, appeared to be needed for ArcA-dependent regulation of both promoters.
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PMID:The complex bet promoters of Escherichia coli: regulation by oxygen (ArcA), choline (BetI), and osmotic stress. 862 94

Aldose reductase (AR; EC 1.1.1.21) is an oxidoreductase that catalyzes the NADPH-dependent conversion of glucose to sorbitol, the first step of the polyol pathway. AR is of great interest due to its implication in the etiology of diabetic complications. In renal medullary cells, AR also plays an osmoregulatory role by accumulating sorbitol to maintain the intracellular osmotic balance during antidiuresis. We have previously cloned the AR cDNA from mouse kidney, and we report here the isolation of the mouse AR gene promoter. Transient transfection of chloramphenicol acetyltransferase reporter constructs containing various 5'-flanking regions of the mouse AR gene in CV1 cells led to the identification of a sequence spanning base pairs -1053 to -1040, required for an enhancer activity in hypertonic compared with isotonic cell culture conditions. This sequence is similar to the tonicity-responsive element first characterized in the betaine-gamma-aminobutyric acid transporter promoter.
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PMID:Isolation of the mouse aldose reductase promoter and identification of a tonicity-responsive element. 900 94