Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycine betaine is a potent osmoprotectant accumulated by Sinorhizobium meliloti to cope with osmotic stress. The biosynthesis of glycine betaine from choline is encoded by an operon of four genes, betICBA, as determined by sequence and mutant analysis. The betI and betC genes are separated by an intergenic region containing a 130-bp mosaic element that also is present between the betB and betA genes. In addition to the genes encoding a presumed regulatory protein (betI), the betaine aldehyde dehydrogenase (betB), and the choline dehydrogenase (betA) enzymes also found in Escherichia coli, a new gene (betC) was identified as encoding a choline sulfatase catalyzing the conversion of choline-O-sulfate and, at a lower rate, phosphorylcholine, into choline. Choline sulfatase activity was absent from betC but not from betB mutants and was shown to be induced indifferently by choline or choline-O-sulfate as were the other enzymes of the pathway. Unlike what has been shown in other bacteria and plants, choline-O-sulfate is not used as an osmoprotectant per se in S. meliloti, but is metabolized into glycine betaine. S. meliloti also can use this compound as the sole carbon, nitrogen, and sulfur source for growth and that depends on a functional bet locus. In conclusion, choline-O-sulfate and phosphorylcholine, which are found in higher plants and fungi, appear to be substrates for glycine betaine biosynthesis in S. meliloti.
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PMID:Presence of a gene encoding choline sulfatase in Sinorhizobium meliloti bet operon: choline-O-sulfate is metabolized into glycine betaine. 973 47

The symbiotic soil bacterium Sinorhizobium meliloti has the capacity to synthesize the osmoprotectant glycine betaine from choline-O-sulfate and choline. This pathway is encoded by the betICBA locus, which comprises a regulatory gene, betI, and three structural genes, betC (choline sulfatase), betB (betaine aldehyde dehydrogenase), and betA (choline dehydrogenase). Here, we report that betICBA genes constitute a single operon, despite the existence of intergenic regions containing mosaic elements between betI and betC, and betB and betA. The regulation of the bet operon was investigated by using transcriptional lacZ (beta-galactosidase) fusions and has revealed a strong induction by choline at concentrations as low as 25 microM and to a lesser extent by choline-O-sulfate and acetylcholine but not by osmotic stress or oxygen. BetI is a repressor of the bet transcription in the absence of choline, and a nucleotide sequence of dyad symmetry upstream of betI was identified as a putative betI box. Measurements of intracellular pools of choline, well correlated with beta-galactosidase activities, strongly suggested that BetI senses the endogenous choline pool that modulates the intensity of BetI repression. In contrast to Escherichia coli, BetI did not repress choline transport. During symbiosis with Medicago sativa, S. meliloti bet gene expression was observed within the infection threads, in young and in mature nodules. The existence of free choline in nodule cytosol, peribacteroid space, and bacteroids was demonstrated, and the data suggest that bet regulation in planta is mediated by BetI repression, as in free-living cells. Neither Nod nor Fix phenotypes were significantly impaired in a betI::omega mutant, indicating that glycine betaine biosynthesis from choline is not crucial for nodulation and nitrogen fixation.
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PMID:The Sinorhizobium meliloti glycine betaine biosynthetic genes (betlCBA) are induced by choline and highly expressed in bacteroids. 1290 15