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)

Thiolase of Clostridium acetobutylicum is an important enzyme involved in both, acid and solvent fermentation. Two thiolase genes (thlA and thIB) have been cloned and sequenced from Clostridium acetobutylicum DSM 792, showing high homology to each other and to thiolases of PHA-synthesizing bacteria. The thlA gene is identical to the gene already cloned and sequenced from strain ATCC 824 (Stim-Herndon et al., 1995, Gene 154: 81-85). Using primer extension and S1 nuclease analysis a transcriptional start site was identified 102 bp upstream of the thlA start codon. This site was preceded by a region that exhibits high similarity to the sigma70 consensus promoter sequences of Gram-positive and -negative bacteria. Regulation of thlA and thlB was studied at the transcriptional level to elucidate the specific function of each gene. Non-radioactive primer extension analysis using fluorescein-labelled oligonucleotides and Northern blot analysis revealed high levels of thlA transcripts in acid- and solvent-producing cells. During an induced shift of a continuous culture from acid to solvent formation, the transcript level transiently decreased to a minimum, 3 to 7 h after induction. The thlA transcript length is about 1.4 kb, indicating a monocistronic organisation, whereas genetic organization and reverse transcription (RT)-PCR analysis indicated that thlB forms an operon with two other adjacent genes, thlR and thlC. Transcription and regulation of the thlB operon was studied using RTPCR and showed a very low expression in acid- and solvent-producing cells. Heterologously expressed clostridial ThlB showed high thiolase activity in Escherichia coli. The N-terminal part of ThlR possesses a potential helix-turn-helix motif and shows significant homology to regulatory proteins belonging to the TetR/AcrR family of transcriptional regulators. ThlR possibly acts as a transcriptional repressor of thlB operon expression. The data provide strong evidence that ThlA is involved in the metabolism of both acid and solvent formation, whereas the physiological function of ThlB has yet to be elucidated.
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PMID:Differential regulation of two thiolase genes from Clostridium acetobutylicum DSM 792. 1107 29

We report on the cloning of the gene smeT, which encodes the transcriptional regulator of the Stenotrophomonas maltophilia efflux pump SmeDEF. SmeT belongs to the TetR and AcrR family of transcriptional regulators. The smeT gene is located upstream from the structural operon of the pump genes smeDEF and is divergently transcribed from those genes. Experiments with S. maltophilia and the heterologous host Escherichia coli have demonstrated that SmeT is a transcriptional repressor. S1 nuclease mapping has demonstrated that expression of smeT is driven by a single promoter lying close to the 5' end of the gene and that expression of smeDEF is driven by an unique promoter that overlaps with promoter PSMET: The level of expression of smeT is higher in smeDEF-overproducing S. maltophilia strain D457R, which suggests that SmeT represses its own expression. Band-shifting assays have shown that wild-type strain S. maltophilia D457 contains a cellular factor(s) capable of binding to the intergenic smeT-smeD region. That cellular factor(s) was absent from smeDEF-overproducing S. maltophilia strain D457R. The sequence of smeT from D457R showed a point mutation that led to a Leu166Gln change within the SmeT protein. This change allowed overexpression of both smeDEF and smeT in D457R. It was noteworthy that expression of wild-type SmeT did not fully complement the smeT mutation in D457R. This suggests that the wild-type protein is not dominant over the mutant SmeT.
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PMID:Cloning and characterization of SmeT, a repressor of the Stenotrophomonas maltophilia multidrug efflux pump SmeDEF. 1238 40

A small plasmid designated pAR141 was isolated from Lactococcus lactis subsp. lactis M14 and its complete 1,594 base pair nucleotide sequence was determined. Analysis of the sequence indicated that this plasmid does not carry any industrially important determinants besides the elements involved in plasmid replication and control. The transcriptional repressor CopG and replication initiation protein RepB appeared as a single operon. A small countertranscribed RNA (ctRNA) coding region was found between the copG and repB genes. The double strand origin (dso) and single strand origin (sso) of rolling circle replicating (RCR) plasmids were also identified in pAR141, suggesting that this plasmid replicates by rolling circle (RC) mode. This observation was supported by S1 nuclease and Southern hybridization analyses.
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PMID:DNA sequence analysis of a small cryptic plasmid from Lactococcus lactis subsp. lactis M14. 1667 13