The EF-G-like GTPase Snu114p regulates spliceosome dynamics mediated by Brr2p, a DExD/H box ATPase.
Binding of a pre-mRNA substrate triggers spliceosome activation, whereas the release of the mRNA product triggers spliceosome disassembly. The mechanisms that underlie the regulation of these rearrangements remain unclear. We find evidence that the GTPase Snu114p mediates the regulation of spliceosome activation and disassembly. Specifically, both unwinding of U4/U6, required for spliceosome activation, and disassembly of the postsplicing U2/U6.U5.intron complex are repressed by Snu114p bound to GDP and derepressed by Snu114p bound to GTP or nonhydrolyzable GTP analogs. Further, similar to U4/U6 unwinding, spliceosome disassembly requires the DExD/H box ATPase Brr2p. Together, our data define a common mechanism for regulating and executing spliceosome activation and disassembly. Although sequence similarity with EF-G suggests Snu114p functions as a molecular motor, our findings indicate that Snu114p functions as a classic regulatory G protein. We propose that Snu114p serves as a signal-dependent switch that transduces signals to Brr2p to control spliceosome dynamics.
Small
Eliza C
EC
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA.
Leggett
Stephanie R
SR
Winans
Adrienne A
AA
Staley
Jonathan P
JP
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D053487:DEAD-box RNA Helicases; D006153:Guanosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D007438:Introns / Q000235:genetics; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation / Q000187:drug effects; D020365:RNA Helicases / Q000032:analysis; D012316:RNA Nucleotidyltransferases / Q000032:analysis; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000235:genetics / Q000502:physiology*; D012265:Ribonucleotides / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D017381:Spliceosomes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear; D012097:Repressor Proteins; D017415:Ribonucleoprotein, U5 Small Nuclear; D012265:Ribonucleotides; C472240:SNU114 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C405484:U2 small nuclear RNA; C405485:U5 small nuclear RNA; C405486:U6 small nuclear RNA; D006153:Guanosine Diphosphate; C065326:xanthosine 5'-triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D012316:RNA Nucleotidyltransferases; C104158:BRR2 protein, S cerevisiae; C067135:PRP22 protein, S cerevisiae; C088939:PRP28 protein, S cerevisiae; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases