Characterization of dominant-negative mutants of the DEAH-box splicing factors Prp22 and Prp16.

TitleCharacterization of dominant-negative mutants of the DEAH-box splicing factors Prp22 and Prp16.
Publication TypeJournal Article
Year of Publication2002
AuthorsSchneider S, Hotz H-R, Schwer B
JournalJ Biol Chem
Date Published2002 May 3
KeywordsAdenosine Triphosphatases, DEAD-box RNA Helicases, DNA Mutational Analysis, Fungal Proteins, Kinetics, Mutagenesis, Site-Directed, Plasmids, Recombinant Proteins, RNA Helicases, RNA Splicing, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spliceosomes

Saccharomyces cerevisiae Prp22 and Prp16 are RNA-dependent ATPases required for pre-mRNA splicing. Both proteins are members of the DEXH-box family of nucleic acid-dependent NTPases. Prior mutational analysis of Prp22 and Prp16 identified residues within conserved motifs I (GXGKT), II (DEAH), and VI (QRXGRXGR) that are required for their biological activity. Nonfunctional Prp22 and Prp16 mutants exerted a dominant negative effect on cell growth. Here we show that overexpression of lethal Prp22 mutants leads to accumulation of unspliced pre-mRNAs and excised introns in vivo. The biochemical basis for the lethality and inhibition of splicing in vivo was determined by purifying and characterizing recombinant mutant proteins. The lethal Prp22 mutants D603A and E604A in motif II and Q804A and R808A in motif VI were defective for ATP hydrolysis and mRNA release from the spliceosome, but were active in promoting step 2 transesterification. Lethal Prp16 mutants G378A and K379A in motif I; D473A and E474A in motif II; and Q685A, G688A, R689A, and R692A in motif VI were defective for ATP hydrolysis and step 2 transesterification chemistry. The ATPase-defective mutants of Prp16 and Prp22 bound to spliceosomes in vitro and blocked the function of the respective wild-type proteins in trans. Comparing the mutational effects in Prp16 and Prp22 highlights common as well as distinct structural requirements for the ATP-dependent steps in pre-mRNA splicing.

Alternate JournalJ. Biol. Chem.
PubMed ID11856747
Grant ListGM50288 / GM / NIGMS NIH HHS / United States

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