Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mycoplasma pneumoniae adherence to host cells is a multifactorial process that requires the cytadhesin P1 and additional accessory proteins. The hmw gene cluster consists of the genes p30, hmw3, and hmw1, the products of which are known to be essential for cytadherence, the rpsD gene, and six open reading frames of unknown function. Putative transcriptional terminators flank this locus, raising the possibility that these genes are expressed as a single transcriptional unit. However, S1 nuclease protection and primer extension experiments identified probable transcriptional start sites upstream of the p32, p21, p50, and rpsD genes. Each was preceded at the appropriate spacing by the -10-like sequence TTAAAATT, but the -35 regions were not conserved. Analysis of the M. pneumoniae genome sequence indicated that this promoter-like sequence is found upstream of only a limited number of open reading frames, including the genes for P65 and P200, which are structurally related to HMW1 and HMW3. Promoter deletion studies demonstrated that the promoter-like region upstream of p21 was necessary for the expression of p30 and an hmw3-cat fusion in M. pneumoniae, while deletion of the promoter-like region upstream of p32 had no apparent effect. Analysis by reverse transcription-PCR confirmed transcriptional linkage of all the open reading frames in the hmw gene cluster. Taken together, these findings suggest that the genes of this locus constitute an operon expressed from overlapping transcripts.
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PMID:Transcriptional analysis of the hmw gene cluster of Mycoplasma pneumoniae. 1043 70

A multiple-gene locus for polyamine uptake and utilization was discovered in Pseudomonas aeruginosa PAO1. This locus contained nine genes designated spuABCDEFGHI (spu for spermidine and putrescine utilization). The physiological functions of the spu genes in utilization of two polyamines (putrescine and spermidine) were analyzed by using Tn5 transposon-mediated spu knockout mutants. Growth and uptake experiments support that the spuDEFGH genes specify components of a major ABC-type transport system for spermidine uptake, and enzymatic measurements indicated that spuC encodes putrescine aminotransferase with pyruvate as the amino group receptor. Although spuA and spuB mutants showed an apparent defect in spermidine utilization, the biochemical functions of the gene products have yet to be elucidated. Assays of lacZ fusions demonstrated the presence of agmatine-, putrescine-, and spermidine-inducible promoters for the spuABCDEFGH operon and the divergently transcribed spuI gene of unknown function. Since the observed induction effect of agmatine was abolished in an aguA mutant where conversion of agmatine into putrescine was blocked, putrescine or spermidine, but not agmatine, serves as the inducer molecule of the spuA-spuI divergent promoters. S1 nuclease mappings confirmed further the induction effects of the polyamines on transcription of the divergent promoters and localized the transcription initiation sites. Gel retardation assays with extracts from the cells grown on putrescine or spermidine demonstrated the presence of a polyamine-responsive regulatory protein interacting with the divergent promoter region. Finally, the absence of the putrescine-inducible spuA expression and putrescine aminotransferase (spuC) formation in the cbrB mutant indicated that the spu operons are regulated by the global CbrAB two-component system perhaps via the putative polyamine-responsive transcriptional activator.
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PMID:Functional analysis and regulation of the divergent spuABCDEFGH-spuI operons for polyamine uptake and utilization in Pseudomonas aeruginosa PAO1. 1208 45

We cloned a DNA fragment that suppressed the aerial-mycelium-deficient phenotype in an amfS mutant of Streptomyces griseus when it was introduced into the cells via a high-copy-number plasmid. The sasABCDR gene cluster was identified as being responsible for this suppressive activity. The proteins encoded by sasABCD were of unknown function, but the operon structure was found to be conserved in all the strains of Streptomyces spp. and related organisms whose genomes have been sequenced. sasR, the flanking opposite coding sequence, encoded a putative DNA-binding protein. Subcloning revealed that the presence of all five coding sequences was essential for complete suppression. Scanning electron microscopy of Streptomyces griseus strains carrying the sas gene cluster at a high copy-number revealed that bundle-like structures consisting of several aerial hyphae were often formed. S1 nuclease protection analyses were performed to identify the transcriptional start site in the promoters preceding sasA and sasR. The promoter preceding sasA was highly active during vegetative growth. Null mutants for sasABCD among the S. griseus and S. coelicolor A3(2) cells exhibited bald phenotypes; this suggested a positive regulatory role of this gene cluster in the onset of morphogenesis in these two phylogenetically distinct Streptomyces species.
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PMID:Identification of sas, a conserved gene cluster involved in the regulation of aerial mycelium formation in Streptomyces griseus. 1904 34


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