title: MLN51 stimulates the RNA-helicase activity of eIF4AIII.
abstract: The core of the exon-junction complex consists of Y14, Magoh, MLN51 and eIF4AIII, a DEAD-box RNA helicase. MLN51 stimulates the ATPase activity of eIF4AIII, whilst the Y14-Magoh complex inhibits it. We show that the MLN51-dependent stimulation increases both the affinity of eIF4AIII for ATP and the rate of enzyme turnover; the K(M) is decreased by an order of magnitude and k(cat) increases 30 fold. Y14-Magoh do inhibit the MLN51-stimulated ATPase activity, but not back to background levels. The ATP-bound form of the eIF4AIII-MLN51 complex has a 100-fold higher affinity for RNA than the unbound form and ATP hydrolysis reduces this affinity. MLN51 stimulates the RNA-helicase activity of eIF4AIII, suggesting that this activity may be functionally important.
authors: Laboratory of Macromolecular Structure, Institute of Molecular and Cell Biology, Singapore, Singapore.
authors: Christian G
authors: CG
authors: Noble
authors: Haiwei
authors: H
authors: Song
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D039601:Eukaryotic Initiation Factor-4A / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005091:Exons / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction / Q000379:methods; D014176:Protein Biosynthesis; D012313:RNA / Q000235:genetics; D020365:RNA Helicases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D013379:Substrate Specificity; D014158:Transcription, Genetic
chemical_list: D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D012313:RNA; D000255:Adenosine Triphosphate; D039601:Eukaryotic Initiation Factor-4A; D000251:Adenosine Triphosphatases; D020365:RNA Helicases