Heterogeneous nuclear ribonucleoprotein K protein associates with multiple mitochondrial transcripts within the organelle.
Heterogeneous nuclear ribonucleoprotein K (hnRNP K) protein interacts with a subset of cellular RNAs. We used K protein as a bait in the yeast three-hybrid screen to identify RNAs that bind K protein in vivo. A large number of K protein-binding RNA clones were identified from a human hybrid RNA library. These sequences consisted of C-rich patches and were G-poor. Unexpectedly, several of the RNA clones were encoded by the mitochondrial genome. In a subsequent three-hybrid screen of a hybrid RNA library generated from a mouse liver mitochondrial genome, K protein bound RNA sequences encoded by different loci spanning nearly the entire mitochondrial genome. Western blot analysis of extracts from mitochondria and mitochondrial fractions showed that K protein is localized within mitoplasts. Reverse transcriptase PCR of RNA co-immunoprecipitated with K protein from lysates of isolated mitochondria showed that K protein is associated with several processed mitochondrial transcripts. In contrast, in the same assay, the polycistronic nascent mtRNA bound K protein weakly or not at all. Results of this study suggest that K protein acts within functional modules that are responsible for expression of genes in mitochondria.
Ostrowski
Jerzy
J
Department of Gastroenterology, Medical Center for Postgraduate Education, Maria Sklodowska-Curie Memorial Cancer Center, and the Institute of Oncology, 02-781 Warsaw, Poland. jostrow@warman.com.pl
Wyrwicz
Lucjan
L
Rychlewski
Leszek
L
Bomsztyk
Karol
K
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics*; D017930:Genes, Reporter; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D051379:Mice; D008930:Mitochondria, Liver / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012332:RNA, Heterogeneous Nuclear / Q000235:genetics; D016601:RNA-Binding Proteins / Q000378:metabolism; D011817:Rabbits; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000235:genetics
D017931:DNA Primers; D004272:DNA, Mitochondrial; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012332:RNA, Heterogeneous Nuclear; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D001616:beta-Galactosidase