Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete nucleotide sequence of the Sesbania mosaic virus (SeMV) genomic RNA was determined by sequencing overlapping cDNA clones. The SeMV genome is 4149 nucleotides in length and encodes four potential overlapping open reading frames (ORFs). Comparison of the nucleotide sequence and the deduced amino acid sequence of the four ORFs of SeMV with that of other sobemoviruses revealed that SeMV was closest to southern bean mosaic virus Arkansas isolate (SBMV-Ark, 73% identity). The 5' non-coding regions of SeMV, SBMV and southern cowpea mosaic virus (SCPMV) are nearly identical. However ORF1 of SeMV which encodes for a putative movement protein of M(r) 18370 has only 34% identity with SBMV-Ark. ORF 2 encodes a polyprotein containing the serine protease, genome linked viral protein (VPg) and RNA dependent RNA polymerase domains and shows 78% identity with SBMV-Ark. The N-terminal amino acid sequence of VPg was found to be TLPPELSIIEIP, which mapped to the region 326-337 of ORF2 product and the cleavage site between the protease domain and VPg was identified to be E325-T326. The cleavage site between VPg and RNA dependent RNA polymerase was predicted to be E445-T446 based on the amino acid sequence analysis of the polyprotein from different sobemoviruses. ORF3 is nested within ORF2 in a--1 reading frame. The potential ribosomal frame shift signal and the downstream stem-loop structure found in other sobemoviruses are also conserved in SeMV RNA sequence, indicating that ORF3 might be expressed via--1 frame shifting mechanism. ORF4 encodes the coat protein of SeMV, which shows 76 and 66% identity with SBMV-Ark and SCPMV, respectively. Thus the comparison of the non-coding regions and the ORFs of SeMV with other sobemoviruses clearly revealed that it is not a strain of SBMV. Phylogenetic analysis of six different sobemoviruses, including SeMV, suggests that recombination event is not frequent in this group and that SeMV is a distinct member of the genus sobemovirus. The analysis also shows sobemoviruses infecting monocotyledons and dicotyledons fall into two distinct clusters.
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PMID:Complete nucleotide sequence of Sesbania mosaic virus: a new virus species of the genus Sobemovirus. 1131 33

Arthrobacter aurescens DSM 3747 hydrolyzes stereospecifically 5'-monosubstituted hydantoins to alpha-amino acids. The genes involved in hydantoin utilization (hyu) were isolated on an 8.7-kb DNA fragment, and by DNA sequence analysis eight ORFs were identified. The hyu gene cluster includes four genes: hyuP encoding a putative transport protein, the hydantoin racemase gene hyuA, the hydantoinase gene hyuH, and the carbamoylase gene hyuC. The four genes are transcribed in the same direction. Upstream of hyuP and in opposite orientation to the hyu genes, three ORFs were found showing similarities to cytochrome P450 monooxygenase (ORF1, incomplete), to membrane proteins (ORF2), and to ferredoxin (ORF3). ORF8 was found downstream of hyuC and again in opposite orientation to the hyu genes. The gene product of ORF8 displayed similarities to the LacI/GalR family of transcriptional regulators. Reverse transcriptase PCR experiments and Northern blot analysis revealed that the genes hyuPAHC are coexpressed in A. aurescens after induction with 3-N-CH3-IMH. The expression of the hyu operon was not regulated by the putative regulator ORF8 as shown by gene disruption and mobility-shift experiments.
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PMID:Organization of genes responsible for the stereospecific conversion of hydantoins to alpha-amino acids in Arthrobacter aurescens DSM 3747. 1151 66

Human enteric caliciviruses have been assigned to two distinct genera: the Norwalk-like viruses (NLVs) and the Sapporo-like viruses (SLVs). During a 3-year surveillance of gastroenteritis in the South West of England during November 1997-2000, a total of 27 clinical samples containing SLVs were collected. PCR amplicons covering a region of the RNA polymerase gene were obtained from 18 of the SLV samples. Sequence analysis of the PCR products indicated that the SLV isolates could be assigned to one of the two major genetic groups represented by Sapporo and London/92 caliciviruses. One of these isolates belonging to the London/92 group (Bristol/98) was subjected to a complete genome sequence analysis. The full genomic sequence of the Bristol/98 isolate was determined from RNA extracted from a single stool sample and consists of 7490 nucleotides, excluding the poly(A) tail. The genome is organised into two open reading frames (ORFs), similar to that of Manchester SLV although the small ORF overlapping the region encoding the capsid protein observed in Manchester SLV is absent in Bristol/98 SLV. The polyprotein (ORF1) of Bristol/98 SLV consists of 2,280 amino acids and, as observed in all SLVs, the structural protein is encoded in frame and contiguous with the 3' terminus of the ORF1. Phylogenetic studies based on complete capsid sequences and genome arrangements within the SLVs indicate that the human enteric viruses within the "Sapporo-like" virus clade should be divided into two distinct genetic groups analogous to the assignment of the Norwalk-like viruses.
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PMID:Epidemiology of human Sapporo-like caliciviruses in the South West of England: molecular characterisation of a genetically distinct isolate. 1199 91

Omega4514 is the site of a Tn5 lac insertion in the Myxococcus xanthus genome that fuses lacZ expression to a developmentally regulated promoter. DNA upstream of the insertion site was cloned, and the promoter was localized. The promoter resembles vegetative promoters in sequence, and sigma(A) RNA polymerase, the major form of RNA polymerase in growing M. xanthus, initiated transcription from this promoter in vitro. Two complete open reading frames were identified downstream of the promoter and before the Omega4514 insertion. The first gene product (ORF1) has a putative helix-turn-helix DNA-binding motif and shows sequence similarity to transcriptional regulators. ORF2 is most similar to subunit A of glutaconate coenzyme A (CoA) transferase, which is involved in glutamate fermentation. Tn5 lac Omega4514 is inserted in the third codon of ORF3, which is similar to subunit B of glutaconate CoA-transferase. An orf1 disruption mutant exhibited a mild sporulation defect, whereas neither a disruption of orf2 nor insertion Omega4514 in orf3 caused a defect. Based on DNA sequence analysis, the three genes are likely to be cotranscribed with a fourth gene whose product is similar to alcohol dehydrogenases. ORF1 delays and reduces expression of the operon during development, but relief from this negative autoregulation does not fully explain the regulation of the operon, because expression from a small promoter-containing fragment is strongly induced during development of an orf1 mutant. Also, multiple upstream DNA elements are necessary for full developmental expression. These results suggest that transcriptional activation also regulates the operon. Omega4514 is the first example of a developmentally regulated M. xanthus operon that is transcribed by the major vegetative RNA polymerase, and its regulation appears to involve both negative autoregulation by ORF1 and positive regulation by one or more transcriptional activators.
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PMID:Identification of the Omega4514 regulatory region, a developmental promoter of Myxococcus xanthus that is transcribed in vitro by the major vegetative RNA polymerase. 1202 52

We found that the biosynthesis of actinorhodin (Act), undecylprodigiosin (Red), and calcium-dependent antibiotic (CDA) are dramatically activated by introducing certain mutations into the rpoB gene that confer resistance to rifampin to Streptomyces lividans 66, which produces less or no antibiotics under normal growth conditions. Activation of Act and/or Red biosynthesis by inducing mutations in the rpoB gene was shown to be dependent on the mutation's position and the amino acid species substituted in the beta-subunit of the RNA polymerase. Mutation analysis identified 15 different kinds of point mutations, which are located in region I, II, or III of the rpoB gene and, in addition, two novel mutations (deletion of nucleotides 1287 to 1289 and a double substitution at nucleotides 1309 and 1310) were also found. Western blot analyses and S1 mapping analyses demonstrated that the expression of actII-ORF4 and redD, which are pathway-specific regulatory genes for Act and Red, respectively, was activated in the mutants able to produce Act and Red. The ActIV-ORF1 protein (an enzyme for Act biosynthesis) and the RedD protein were produced just after the upregulation of ActII-ORF4 and RedZ, respectively. These results indicate that the mutation in the rpoB gene of S. lividans, resulting in the activation of Act and/or Red biosynthesis, functions at the transcription level by activating directly or indirectly the key regulatory genes, actII-ORF4 and redD. We propose that the mutated RNA polymerase may function by mimicking the ppGpp-bound form in activating the onset of secondary metabolism in STREPTOMYCES:
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PMID:Activation of antibiotic biosynthesis by specified mutations in the rpoB gene (encoding the RNA polymerase beta subunit) of Streptomyces lividans. 1208 71

Viruses of the genus 'Norwalk-like viruses' (NLVs) detected in humans have been genetically classified into two major genetic groups, genogroups I and II (GI and GII), which together are made up of at least 14 genetic subgroups. However, a comparable classification of NLVs in other species remains to be carried out. We sequenced a 2-kb region from within the RNA polymerase gene to the 3' end of open reading frame 2 (ORF2) of two NLV strains previously detected in the caecum contents of healthy pigs. The sequences of the entire ORF2 of these two NLV strains were analyzed for their genetic relationships to 15 human strains, which have already been reported and used as references for the genetic classification of human NLV strains, and additional two strains; one, a human strain which has recently been reported and appears to represent a new genetic subgroup of GII; and the other, an animal NLV strain. Analysis of a matrix showing pairwise identities and topology of a neighbor-joining tree showed that the two swine strains could be classified into a new genetic subgroup of GII on the basis of the amino acid sequences of the entire capsid protein. Grouping of the two swine strains was well corroborated by results of similar analyses of nucleotide sequences of the entire ORF2 and of a 510 base region at the 3' end of ORF1.
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PMID:Viruses detected in the caecum contents of healthy pigs representing a new genetic cluster in genogroup II of the genus "Norwalk-like viruses". 1219 80

Through labeling HEV RNAs with [32P]-phosphate, two subgenomic RNAs at 6.5 to 7.5 h post-infection, one subgenomic RNA at 8.5 to 10.5 h post-infection and none subgenomic RNAs were detected at 21 post-infection or in purified virus. Hybridization results illustrated that the HEV subgenomic RNAs form a 3' nested set which is situated at the 3' end of genome, but their 5' ends do not share a common leader sequence. UV transcription results showed that the HEV subgenomic RNAs were transcribed independently from its promote. Primer extension analysis suggested that the 5' end of large subgenomic RNA was mapped to the initiative region within RNA polymerase region, and the small subgenomic RNA was mapped to the intergenic region between ORF1 and ORF2.
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PMID:[Studies on the subgenomic RNAs of hepatitis E virus]. 1254 57

Virus-like particles (VLPs, named HmTV1-17), about 40 nm in diameter were found in the violet root rot fungus Helicobasidium mompa Tanaka strain No. 17, which had been isolated from an apple tree. Purified preparations of HmTV1-17 contained two species of double-stranded RNA (dsRNA), designated 17L and 17S. cDNAs were constructed from HmTV1-17 genomic dsRNAs purified using CF-11 cellulose column chromatography. The sequences of 17L and 17S cDNA comprised 5,207 and 2,096 bp, respectively. Although 17S has no large open reading flame (ORF) on either strand, 17L has two large overlapping ORFs. The 5' located ORF1 encodes the coat protein (CP, 788 amino acids), whereas the gene product of ORF2, which is in the -1 frame relative to ORF1, shows the typical features of a RNA dependent RNA polymerase (RDRP, 845 amino acids). Phylogenetic analysis based on RDRP showed that HmTV1-17 is closely related to Sphaeropsis sapinea SsRV1, a member of the genus Totivirus from filamentous fungus S. sapinea.
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PMID:Cloning and characterization of a totivirus double-stranded RNA from the plant pathogenic fungus, Helicobasidium mompa Tanaka. 1287 50

Ureases are multisubunit enzymes requiring Ni(2+) for activity. The low pH-inducible urease gene cluster in Streptococcus salivarius 57.I is organized as an operon, beginning with ureI, followed by ureABC (structural genes), and ureEFGD (accessory genes). Urease biogenesis also requires a high-affinity Ni(2+) uptake system. By searching the partial genome sequence of a closely related organism, Streptococcus thermophilus LMG18311, three open reading frame (ORFs) homologous to those encoding proteins involved in cobalamin biosynthesis and cobalt transport (cbiMQO) were identified immediately 3' to the ure operon. To determine whether these genes were involved in urease biogenesis by catalyzing Ni(2+) uptake in S. salivarius, regions 3' to ureD were amplified by PCRs from S. salivarius by using primers identical to the S. thermophilus sequences. Sequence analysis of the products revealed three ORFs. Reverse transcriptase PCR was used to demonstrate that the ORFs are transcribed as part of the ure operon. Insertional inactivation of ORF1 with a polar kanamycin marker completely abolished urease activity and the ability to accumulate (63)Ni(2+) during growth. Supplementation of the growth medium with NiCl(2) at concentrations as low as 2.5 micro M partially restored urease activity in the mutant. Both wild-type and mutant strains showed enhanced urease activity when exogenous Ni(2+) was provided at neutral pH. Enhancement of urease activity by adding nickel was regulated at the posttranslational level. Thus, ORF1, ORF2, and ORF3 are part of the ure operon, and these genes, designated ureM, ureQ, and ureO, respectively, likely encode a Ni(2+)-specific ATP-binding cassette transporter.
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PMID:Identification and characterization of the nickel uptake system for urease biogenesis in Streptococcus salivarius 57.I. 1461 41

Recent studies have demonstrated the widespread contamination of river and seawater with noroviruses (NV), often with more than one strain. The heteroduplex mobility assay (HMA) in which amplicons from study samples are hybridised (by denaturing and reannealing) to amplicons from reference strains and resolved by electrophoresis, has the potential to provide a simple and rapid means to identify samples containing multiple NV strains and to establish the diversity of strains within that sample. PCR amplicons from environmental samples that were tested directly in the HMA assay were shown to contain more than one strain. In order to evaluate HMA for investigations of NV diversity in environmental samples, amplicons from three representative samples were cloned and, for each, 20 amplicons derived from individual clones were analysed by HMA. Between two and six different HMA profiles were demonstrated among clones from a single sample indicating the extent of NV diversity in the sample. Sequence analysis confirmed the relationship of HMA profile and NV 'genotype'. Far greater diversity was seen among Genogroup (G) II (Ni/E3) amplicons than Genogroup (G) I (Ando/E3) amplicons (generated from the RNA dependent RNA polymerase region of the ORF1 of noroviruses), which often contained only a single strain, which is reflective of the greater prevalence of GII NVs over GI NVs. Overall, four GII and four GI strains were identified in these environmental water/sewage samples.
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PMID:Application of the heteroduplex mobility assay (HMA) for the investigation of the genomic diversity among noroviruses in environmental samples. 1523 10


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