Characterization of human MRP/Th RNA and its nuclear gene: full length MRP/Th RNA is an active endoribonuclease when assembled as an RNP.
Vertebrate cells contain a site-specific endoribonuclease (RNase MRP) that cleaves mitochondrial RNA transcribed from the origin of leading-strand mitochondrial DNA replication. This report presents the characterization of the human enzyme and its essential RNA component. Human RNase MRP is a ribonucleoprotein with a nucleus-encoded RNA of 265 nucleotides. As expected, the single-copy RNA coding region is homologous (84%) to the corresponding mouse gene; surprisingly, at least 700 nucleotides of the immediate 5'-flanking region are conserved. The 265-nucleotide MRP RNA and an MRP RNA cleavage product representing the 3'-terminal 108 nucleotides exist in nuclear and mitochondrial RNA isolates; the larger MRP RNA is present in greatest abundance in the nucleus. The putative processing site within the 265-nucleotide MRP RNA is offset from that of mouse MRP RNA, but in each case cleavage is precise and occurs at the sequence ANCCCGC. Oligonucleotide-mediated inhibition experiments reveal that both the 5' and 3' portions of the MRP RNA are involved in cleavage by RNase MRP; this implies that full length MRP RNA complexed with proteins is an active species in vertebrate cells.
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Department of Developmental Biology, Stanford University School of Medicine, CA 94305-5427.
Clayton
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D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D004722:Endoribonucleases / Q000378:metabolism*; D005260:Female; D015698:Genomic Library; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012313:RNA / Q000235:genetics*; D000077278:RNA, Mitochondrial; D016914:Ribonuclease H; D012261:Ribonucleoproteins / Q000378:metabolism*
D004272:DNA, Mitochondrial; D015345:Oligonucleotide Probes; D000077278:RNA, Mitochondrial; D012261:Ribonucleoproteins; D012313:RNA; D004722:Endoribonucleases; C058330:mitochondrial RNA-processing endoribonuclease; D016914:Ribonuclease H