Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have identified a single transcriptional initiation site for the glutamic tRNA and COB (cytochrome b) genes by using the complementary techniques of in vitro capping of RNA and in vitro transcription. In the capping reaction, mitochondrial RNA is labeled with [alpha-32P]GTP by vaccinia virus guanylyltransferase. This reaction is specific for the 5' ends of RNA retaining the terminal triphosphate of transcriptional initiation. Exploiting the extremely low G+C content (18%) of yeast mitochondrial DNA, we digested in vitro capped transcripts from various petite deletion mutants with the G-specific RNase T1. By petite deletion mapping, a capped transcript giving rise to a 51-base RNase T1-generated oligonucleotide was localized near the glutamic tRNA gene. When the sequence of this oligonucleotide was determined, it perfectly matched the DNA sequence 391 base upstream of the glutamic tRNA. Purified yeast mitochondrial RNA polymerase initiated transcription in vitro at the same site as shown by the sequence of the 33-base oligonucleotide product of the reaction performed in the absence of CTP. Initiation starts at a nonanucleotide sequence previously implicated in yeast mitochondrial transcriptional initiation. Because there is no evidence of an initiation site in the 1,050 bases between the glutamic tRNA and COB genes, the two genes are likely to be transcribed together. Further evidence of a long common transcript was provided by RNA blot hybridization.
 ...
PMID:Identification of a single transcriptional initiation site for the glutamic tRNA and COB genes in yeast mitochondria. 613 68

We have studied transcriptional initiation in the mitochondria of the yeast Saccharomyces cerevisiae by analyzing mitochondrial transcripts from grande and petite yeast after labeling in vitro with vaccinia virus guanylyltransferase and [alpha-32P]GTP. This procedure labels triphosphate-terminated RNA which arises from transcriptional initiation. Exploiting the extremely low GC content (18%) of yeast mitochondrial DNA, we digested the in vitro capped transcripts with the G-specific ribonuclease T1; this resulted in 27 oligonucleotides varying in size from 2 to 51 nucleotides. RNA from 14 overlapping petites was analyzed and 20 transcripts were localized by deletion mapping. Nineteen oligonucleotides were sequences and 13 were identified and precisely localized by comparison with known DNA sequences. In all cases, transcription is initiated at a consensus nonanucleotide sequence which can be considered part of the yeast mitochondrial promoter. We identified initiation sites for the 21 S and 14 S rRNAs; the phenylalanine, f-methionine, and glutamic tRNAs; two sites for the OLI-1 gene; and three for the ori (rep) regions. Most promoters appear to give rise to very long multigene primary transcripts. Examples are multigene transcripts for the glutamic tRNA and COB genes and for the OLI-1, serine tRNA, and Var genes. Since the consensus nonanucleotide sequences at the ori regions are similar to those at other transcriptional initiation sites, it is likely that the same RNA polymerase primes DNA replication and gene transcription.
 ...
PMID:Identification of multiple transcriptional initiation sites on the yeast mitochondrial genome by in vitro capping with guanylyltransferase. 631 17