7-2/MRP RNAs in plant and mammalian cells: association with higher order structures in the nucleolus

• Published in: The EMBO journal 1992-10, Vol.11 (10), p.3737-3746
• Main Authors: Kiss, T, Marshallsay, C, Filipowicz, W
• Format: Article
• Language: English
• Subjects: Animals; Arabidopsis - genetics; Arabidopsis thaliana; at7-2 gene; Base Sequence; Biological and medical sciences; cell nucleolus; Cell Nucleolus - chemistry; Cell Nucleolus - metabolism; complementary DNA; ddbj/x65942; DNA; embl/x65942; Endoribonucleases - analysis; Endoribonucleases - genetics; Endoribonucleases - metabolism; Fundamental and applied biological sciences. Psychology; genbank/x65942; Genes, Regulator; Genes. Genome; HeLa Cells; Humans; Mammalia; Mammals; Mitochondria - chemistry; Mitochondria - metabolism; mitochonrial rna processing rna; Molecular and cellular biology; molecular conformation; Molecular genetics; Molecular Sequence Data; Nicotiana - genetics; Nicotiana tabacum; Nucleic Acid Conformation; nucleotide sequences; Plants - genetics; Plants, Toxic; promoter regions; Promoter Regions, Genetic; ribosomes; RNA - genetics; RNA, Mitochondrial; Sequence Homology, Nucleic Acid; small nuclear RNA; structural genes; TATA Box; use element
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1992.tb05459.x

Mammalian MRP (for mitochondrial RNA processing) RNA, also known as 7-2 RNA, is a nuclear encoded small RNA which has been reported to function in two different cellular compartments: in the mitochondria and in the nucleus. The ribonucleoprotein particle which contains the 7-2/MRP RNA, called RNase MRP, has ribonucleolytic activity and shares some structural similarity with RNase P. It has been proposed that in mitochondria, the RNase MRP is responsible for endonucleolytic cleavage of primer RNA during DNA replication. We have characterized the gene and cDNAs encoding 7-2/MRP-like RNA in Arabidopsis and tobacco, and found that in plants this RNA is enriched in nucleoli but is undetectable in purified mitochondria isolated from tobacco leaves or cells grown in suspension. In glycerol gradients tobacco 7-2/MRP RNA cosediments with large approximately 80S structures possibly representing ribosomal precursors. Fractionation of HeLa cells has also revealed that 7-2/MRP resides in the nucleolus and that most of it is associated with complexes sedimenting at approximately 80S, similar to those containing the U3 nucleolar RNA which is known to participate in pre-rRNA processing. These results indicate that the 7-2/MRP ribonucleoparticle may be involved in ribosome biogenesis, in both plant and mammalian cells.