Xp54 and related (DDX6-like) RNA helicases: roles in messenger RNP assembly, translation regulation and RNA degradation.
The DEAD-box RNA helicase Xp54 is an integral component of the messenger ribonucleoprotein (mRNP) particles of Xenopus oocytes. In oocytes, several abundant proteins bind pre-mRNA transcripts to modulate nuclear export, RNA stability and translational fate. Of these, Xp54, the mRNA-masking protein FRGY2 and its activating protein kinase CK2alpha, bind to nascent transcripts on chromosome loops, whereas an Xp54-associated factor, RapA/B, binds to the mRNP complex in the cytoplasm. Over-expression, mutation and knockdown experiments indicate that Xp54 functions to change the conformation of mRNP complexes, displacing one subset of proteins to accommodate another. The sequence of Xp54 is highly conserved in a wide spectrum of organisms. Like Xp54, Drosophila Me31B and Caenorhabditis CGH-1 are required for proper meiotic development, apparently by regulating the translational activation of stored mRNPs and also for sorting certain mRNPs into germplasm-containing structures. Studies on yeast Dhh1 and mammalian rck/p54 have revealed a key role for these helicases in mRNA degradation and in earlier remodelling of mRNP for entry into translation, storage or decay pathways. The versatility of Xp54 and related helicases in modulating the metabolism of mRNAs at all stages of their lifetimes marks them out as key regulators of post-transcriptional gene expression.
Weston
Andrew
A
School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, Scotland, UK.
Sommerville
John
J
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020365:RNA Helicases / Q000737:chemistry / Q000502:physiology*; D012316:RNA Nucleotidyltransferases / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D029867:Xenopus Proteins / Q000737:chemistry / Q000502:physiology*
D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D029867:Xenopus Proteins; C026452:messenger ribonucleoprotein; D012316:RNA Nucleotidyltransferases; C094683:DDX6 protein, human; C486437:Xp54 RNA helicase, Xenopus; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases