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)

The current studies show that mRNAs with 16 different 5'-untranslated regions (varying in length from 68 to 670 nucleotides) are produced from the 3-hydroxy-3-methylglutaryl coenzyme A reductase gene in hamster UT-1 cells. This complex pattern of mRNAs results from a combination of multiple transcription initiation sites and multiple 5' splice donor sites for the intron in the 5'-untranslated region of the gene. Analysis of the multiple mRNAs was made possible by a modification of the S1 nuclease technique in which we used a series of progressively truncated uniformly labeled, single-stranded [32P]DNA probes in addition to the usual end-labeled 32P-probes. All of the reductase mRNAs are diminished when UT-1 cells are incubated with sterols, indicating that all of them are subject to coordinate control.
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PMID:Multiple mRNAs for 3-hydroxy-3-methylglutaryl coenzyme A reductase determined by multiple transcription initiation sites and intron splicing sites in the 5'-untranslated region. 299 Dec 85

The promoter region of the human insulin-receptor (HINSR) gene was isolated from a human chromosome 19 bacteriophage library. With S1 nuclease mapping and primer-extension analysis, we identified multiple transcription-initiation sites. Dexamethasone, a known inducer of HINSR transcription, enhanced transcription of all major transcription-initiation sites. DNA sequence analysis indicated that the HINSR promoter has neither a TATA box nor a CAAT box. The HINSR promoter region contains six GGGCGG sequences that may be binding sites for the transcription factor Sp1. In addition, there were three TCCC sequences that were putative promoter regulatory regions. The HINSR gene promoter has structural similarity to the epidermal growth factor receptor gene promoter and has some features of the promoter of the meglutol (hydroxymethylglutaryl, HMG) CoA reductase gene and the early promoter of simian virus 40.
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PMID:Sequence and analysis of promoter region of human insulin-receptor gene. 341 Jan 65

FAS1, the structural gene of the pentafunctional fatty acid synthetase subunit beta in Saccharomyces cerevisiae has been sequenced. Its reading frame represents an intron-free nucleotide sequence of 5,535 base pairs, corresponding to a protein of 1,845 amino acids with a molecular weight of 205,130 daltons. In addition to the coding sequence, 1,468 base pairs of its 5'-flanking region were determined. S1 nuclease mapping revealed two transcriptional initiation sites; 5 and 36 base pairs upstream of the translational start codon. Within the flanking sequences two TATATAAA boxes, several A-rich and T-rich blocks and a TAG...TATGTT...TATGTT...TTT sequence were found and are discussed as transcriptional initiation and termination signals, respectively. The order of catalytic domains in the cluster gene was established by complementation of defined fas1 mutants with overlapping FAS1 subclones. Acetyl transferase (amino acids 1-468) is located proximal to the N-terminus of subunit beta, followed by the enoyl reductase (amino acids 480-858), the dehydratase (amino acids 1,134-1,615) and the malonyl/palmityl transferase (amino acids 1,616-1,845) domains. One major inter-domain region of about 276 amino acids with so far unknown function was found between the enoyl reductase and dehydratase domains. The substrate-binding serine residues of acetyl, malonyl and palmityl transferases were identified within the corresponding domains. Significant sequence homologies exist between the acyl transferase active sites of yeast and animal fatty acid synthetases. Similarly, a putative sequence of the enoyl reductase active site was identified.
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PMID:The pentafunctional FAS1 gene of yeast: its nucleotide sequence and order of the catalytic domains. 352 50

The rate-limiting enzyme of cholesterol biosynthesis, HMG CoA reductase, is controlled by negative feedback regulation of transcription. We have isolated the reductase gene from a bacteriophage lambda genomic library prepared from hamster UT-1 cells. The 25 kilobase gene is split into 20 exons. The 5' untranslated and promoter regions differ from those of previously characterized genes. The 5' untranslated region encompasses as many as 670 nucleotides; contains up to eight AUG codons upstream of the codon used to initiate translation; and has multiple transcription initiation sites as determined by S1 nuclease mapping and primer extension analysis. The promoter region lacks a characteristic TATA box and CCAAT box; is rich in G + C residues (65%); and contains repeat sequences homologous to the 21 base pair repeats of the SV40 promoter. These unusual features may be relevant to the mechanism of expression of "housekeeping" genes, particularly those that are subject to negative feedback regulation.
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PMID:HMG CoA reductase: a negatively regulated gene with unusual promoter and 5' untranslated regions. 608 70

The nucleotide sequence of the E.coli metF gene (888 nucleotides), coding for 5-10 methylene tetrahydrofolate reductase, has been determined. The metF gene product was identified in maxicells and found to be a protein of subunit molecular weight 33,000, in agreement with the size of the coding region. The starting point for metF transcription was determined by S1 nuclease mapping. No structural evidence was found for an attenuation mechanism regulating the independent metF transcriptional unit. Comparison of the regulatory region preceding the metF structural gene with the 5' flanking region of the metBL operon shows some homology spanning 24 nucleotides. These homologous sequences could be operator structures belonging to the two transcriptional units, metF and metBL, and recognized by the same regulatory protein.
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PMID:Nucleotide sequence of metF, the E. coli structural gene for 5-10 methylene tetrahydrofolate reductase and of its control region. 635 36

In order to examine whether splicing can occur cotranscriptionally in mammalian nuclei, we mapped exon-intron boundaries on nascent RNA chains transcribed by RNA polymerase II. A procedure that allows fractionation of nuclei into a chromatin pellet containing DNA, histones, and ternary transcription complexes and a supernatant containing the bulk of the nonhistone proteins and RNAs that are released from their DNA templates was developed. The transcripts of the genes encoding DBP, a transcriptional activator protein, and HMG coenzyme A reductase recovered from the chromatin pellet and the supernatant were analyzed by S1 nuclease mapping. The large majority of the RNA molecules from the pellet appeared to be nascent transcripts, since, in contrast to the transcripts present in the supernatant, they were not cleaved at the polyadenylation site but rather contained heterogeneous 3' termini encompassing this site. Splicing intermediates could be detected among nascent and released transcripts, suggesting that splicing occurs both cotranscriptionally and posttranscriptionally. Our results also indicate that polyadenylation is not required for the splicing of the last DBP intron. In addition to allowing detailed structural analysis of nascent RNA chains, the physical isolation of nascent transcripts also yields reliable measurements of relative transcription rates.
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PMID:Physical isolation of nascent RNA chains transcribed by RNA polymerase II: evidence for cotranscriptional splicing. 752 61

Mycobacterium tuberculosis is a natural mutant with inactivated oxidative stress regulatory gene oxyR. This characteristic has been linked to the exquisite sensitivity of M. tuberculosis to isonicotinic acid hydrazide (INH). In the majority of mycobacteria tested, including M. tuberculosis, oxyR is divergently transcribed from ahpC, a gene encoding a homolog of the subunit of alkyl hydroperoxide reductase that carries out substrate peroxide reduction. Here we compared ahpC expression in Mycobacterium smegmatis, a mycobacterium less sensitive to INH, with that in two highly INH sensitive species, M. tuberculosis and Mycobacterium aurum. The ahpC gene of M. smegmatis was cloned and characterized, and the 5' ends of ahpC mRNA were mapped by S1 nuclease protection analysis. M. smegmatis AhpC and eight other polypeptides were inducible by exposure to H2O2 or organic peroxides, as determined by metabolic labeling and Western blot (immunoblot) analysis. In contrast, M. aurum displayed differential induction of only one 18-kDa polypeptide when exposed to organic peroxides. AhpC could not be detected in this organism by immunological means. AhpC was also below detection levels in M. tuberculosis H37Rv. These observations are consistent with the interpretation that ahpC expression and INH sensitivity are inversely correlated in the mycobacterial species tested. In further support of this conclusion, the presence of plasmid-borne ahpC reduced M. smegmatis susceptibility to INH. Interestingly, mutations in the intergenic region between oxyR and ahpC were identified and increased ahpC expression observed in deltakatG M. tuberculosis and Mycobacterium bovis INH(r) strains. We propose that mutations activating ahpC expression may contribute to the emergence of INH(r) strains.
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PMID:Oxidative stress response and its role in sensitivity to isoniazid in mycobacteria: characterization and inducibility of ahpC by peroxides in Mycobacterium smegmatis and lack of expression in M. aurum and M. tuberculosis. 865 66

In contrast to the intact oxyR gene (a homolog of the central regulator of peroxide stress response in enteric bacteria) in Mycobacterium leprae, this gene is inactive in all strains of M. tuberculosis. In both species, oxyR is divergently transcribed from ahpC, which encodes a homolog of alkyl hydroperoxide reductase. To initiate investigations of the regulation of oxidative stress in mycobacteria and consequences of the elimination of oxyR in M. tuberculosis, in this work we tested the hypothesis that mycobacterial OxyR acts as a DNA binding protein and analyzed its interactions with the oxyR and ahpC promoters. M. leprae OxyR was overproduced and purified, and its binding to the oxyR-ahpC intergenic region of M. leprae was demonstrated. By using a sequential series of overlapping DNA fragments, the minimal OxyR binding site was delimited to a 30-bp DNA segment which included a palindromic sequence conforming with the established rules for the LysR family of regulators. A consensus sequence for the mycobacterial OxyR recognition site (cTTATCggc-N3-gccGATAAg) was deduced based on its conservation in different mycobacteria. A variance in two potentially critical nucleotides within this site was observed in M. tuberculosis, in keeping with its reduced affinity for OxyR. Transcription of plasmid-borne M. leprae oxyR and ahpC was investigated in M. smegmatis and M. bovis BCG by S1 nuclease protection and transcriptional fusion analyses. Two mRNA 5' ends were detected in each direction: (i) P1oxyR and P2oxyR and (ii) P1ahpC and P2ahpC. The binding site for OxyR overlapped P1oxyR, reminiscent of the autoregulatory loops controlling expression of oxyR in enteric bacteria and characteristic of the LysR superfamily in general. This site was also centered 65 bp upstream of P1ahpC, matching the usual position of LysR-type recognition sequences in relationship to positively controlled promoters. Superimposed on these features was the less orthodox presence of multiple transcripts and their unique arrangement, including a region of complementarity at the 5' ends of the P2ahpC and P2oxyR mRNAs, suggesting the existence of complex regulatory relationships controlling oxyR and ahpC expression in mycobacteria.
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PMID:Interactions of OxyR with the promoter region of the oxyR and ahpC genes from Mycobacterium leprae and Mycobacterium tuberculosis. 907 28