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 objective of this study was to explore the nature of the antigen-specific T cell response in giant cell arteritis by analyzing clonally expanded T cells in temporal artery specimens. In temporal artery tissue from eight patients, 10% of the T cell receptor beta chain repertoire was systematically screened for clonal T cells by reverse-transcriptase polymerase chain reaction with selected BV, BJ, and BC specific primers and by direct sequencing of the amplified product. In five additional patients tissue-derived T cell clones were characterized. All expanded clonotypes were analyzed for their presence at different sites of the inflamed artery. T cell lines were tested for their proliferation to autologous monocytes pulsed with temporal artery extracts from patients with giant cell arteritis, polymyalgia rheumatica, and unrelated diseases. Clonally expanded T cells were identified in 30% of the BV-J combinations of the sampled repertoire. A subset of these clones were encountered at different sites of the inflammation, but not in the peripheral blood. The T cell receptor beta chain sequences were diverse. The patients had between none and five such clonotypes in the sampled repertoire, suggesting that only few T cell specificities in each patient are involved in antigen recognition. One of these T cell clonotypes was shown to proliferate in response to an antigen selectively expressed in temporal artery specimens from giant cell arteritis and from polymyalgia rheumatica patients. Clonotypes with identical T cell receptor beta chain sequences can be found at distinct sites of the inflammation in giant cell arteritis, suggesting recognition of the same antigen at different locations. At least for some of these T cell clones the antigen is shared between different giant cell arteritis and polymyalgia rheumatica patients but not expressed in temporal arteries of patients with unrelated diseases. While different HLA-DR4+ patients utilize distinct T cell specificities, the actual number of responding T cells in individual patients is small and may be disease limiting.
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PMID:Recognition of tissue residing antigen by T cells in vasculitic lesions of giant cell arteritis. 895 56

Deviations from the universal genetic code have evolved independently several times in ciliated protozoa. Thus, in some species UAA and UAG are no longer used as termination codons, but are read as glutamine, whereas in the genus Euplotes , UGA is translated as cysteine. We have investigated the nature of the tRNACys isoacceptor responsible for decoding UGA in Euplotes cells. Southern hybridization analyses indicated that a single DNA molecule of 630 bp encoding tRNACys exists in the macronucleus of Euplotes octocarinatus . Cloning and sequencing of this fragment revealed that it contains only one copy of a tRNACys gene, which codes for a normal tRNACys with GCA anticodon. This is the first report of the characterization of a tRNA gene in any hypotrichous ciliate. It contains putative signals for initiation and termination of transcription by RNA polymerase III and can be transcribed efficiently in vitro in HeLa cell nuclear extract. Intensive studies on the DNA and tRNA level involving PCR analyses have not disclosed the existence of any tRNA Cys isoacceptor with UCA or ICA anticodons. Translation of the UGA codon by tRNA sub GCA sup Cys necessitates a G:A mispairing in the first anticodon position. We discuss a number of aspects which might contribute to the finding that a near-cognate tRNA isoacceptor efficiently translates the UGA stop codon.
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PMID:The hypotrichous ciliate Euplotes octocarinatus has only one type of tRNACys with GCA anticodon encoded on a single macronuclear DNA molecule. 975 21

The gene for the DNA primase encoded by Salmonella typhimurium bacteriophage SP6 has been cloned and expressed in Escherichia coli and its 74-kDa protein product purified to homogeneity. The SP6 primase is a DNA-dependent RNA polymerase that synthesizes short oligoribonucleotides containing each of the four canonical ribonucleotides. GTP and CTP are both required for the initiation of oligoribonucleotide synthesis. In reactions containing only GTP and CTP, SP6 primase incorporates GTP at the 5'-end of oligoribonucleotides and CMP at the second position. On synthetic DNA templates, pppGpC dinucleotides are synthesized most rapidly in the presence of the sequence 5'-GCA-3'. This trinucleotide sequence, containing a cryptic dA at the 3'-end, differs from other known bacterial and phage primase recognition sites. SP6 primase shares some properties with the well-characterized E. colibacteriophage T7 primase. The T7 DNA polymerase can use oligoribonucleotides synthesized by SP6 primase as primers for DNA synthesis. However, oligoribonucleotide synthesis by SP6 primase is not stimulated by either the E. coli- or the T7-encoded ssDNA binding protein. An amino acid sequence alignment of the SP6 and T7 primases, which share only 22.4% amino acid identity, indicates amino acids likely critical for oligoribonucleotide synthesis as well as a putative Cys(3)His zinc finger motif that may be involved in DNA binding.
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PMID:Characterization of a novel DNA primase from the Salmonella typhimurium bacteriophage SP6. 1067 13

The sequence of canine COL1A1 cDNA was determined from four overlapping COL1A1 RT-PCR products generated from canine fibroblast RNA. In the translated region, nucleotide identity between canine and human COL1A1 cDNA was 93.2%, although the canine sequence lacked nucleotides 204 to 215 in the region coding for the N-propeptide. Amino acid identity was 97.7%. Total RNA and type I collagen were collected from cultured skin fibroblasts of a 12-week-old male golden retriever with pathologic fractures suggestive of osteogenesis imperfecta (OI) and dentinogenesis imperfecta. Sequential, overlapping approximately 1,000-bp fragments of COL1A1 and COL1A2 cDNA were each amplified by RT-PCR using primers containing 5' T7 polymerase sites. These PCR products were transcribed with T7 RNA polymerase, hybridized into RNA duplexes, and cleaved at mismatch sites with RNase. The proband had an unique cleavage pattern for the fragment of COL1A1 mRNA spanning nucleotides 709 to 1,531. Sequence analysis identified a G to C point mutation for nucleotide 1,276, predicting a codon change from glycine (GGA) to alanine (GCA) for amino acid 208. This change disrupts the normal Gly-X-Y pattern of the collagen triple helix. Restriction enzyme digestion of the RT-PCR product was consistent with a heterozygous COL1A1 mutation. Type I collagen was labeled with 3H-proline, salt precipitated, and analyzed by SDS-PAGE. Pepsin digested alpha chains were over-hydroxylated, and procollagen processing was delayed. Thus, canine and human OI appear homologous in terms of clinical presentation, etiology, and pathogenesis.
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PMID:Sequence of normal canine COL1A1 cDNA and identification of a heterozygous alpha1(I) collagen Gly208Ala mutation in a severe case of canine osteogenesis imperfecta. 1114 34

The N protein of phage lambda acts with Escherichia coli Nus proteins at RNA sites, NUT, to modify RNA polymerase (RNAP) to a form that overrides transcription terminators. These interactions have been thought to be the primary determinants of the effectiveness of N-mediated antitermination. We present evidence that the associated promoter, in this case the lambda early P(R) promoter, can influence N-mediated modification of RNAP even though modification occurs at a site (NUTR) located downstream of the intervening cro gene. As predicted by genetic analysis and confirmed by in vivo transcription studies, a combination of two mutations in P(R), at positions -14 and -45 (yielding P(R-GA)), reduces effectiveness of N modification, while an additional mutation at position -30 (yielding P(R-GCA)) suppresses this effect. In vivo, the level of P(R-GA)-directed transcription was twice as great as the wild-type level, while transcription directed by P(R-GCA) was the same as that directed by the wild-type promoter. However, the rate of open complex formation at P(R-GA) in vitro was roughly one-third the rate for wild-type P(R). We ascribe this apparent discrepancy to an effect of the mutations in P(R-GCA) on promoter clearance. Based on the in vivo experiments, one plausible explanation for our results is that increased transcription can lead to a failure to form active antitermination complexes with NUT RNA, which, in turn, causes failure to read through downstream termination sites. By blocking antitermination and thus expression of late functions, the effect of increased transcription through nut sites could be physiologically important in maintaining proper regulation of gene expression early in phage development.
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PMID:Evidence that the promoter can influence assembly of antitermination complexes at downstream RNA sites. 1651 52