RESUMEN

Many alleles of human disease genes have mutations within splicing consensus sequences that activate cryptic splice sites. In Caenorhabditis elegans, the unc-73(e936) allele has a G-to-U mutation at the first base of the intron downstream of exon 15, which results in an uncoordinated phenotype. This mutation triggers cryptic splicing at the -1 and +23 positions and retains some residual splicing at the mutated wild-type (wt) position. We previously demonstrated that a mutation in sup-39, a U1 snRNA gene, suppresses e936 by increasing splicing at the wt splice site. We report here the results of a suppressor screen in which we identify three proteins that function in cryptic splice site choice. Loss-of-function mutations in the nonessential splicing factor smu-2 suppress e936 uncoordination through changes in splicing. SMU-2 binds SMU-1, and smu-1(RNAi) also leads to suppression of e936. A dominant mutation in the conserved C-terminal domain of the C. elegans homolog of the human tri-snRNP 27K protein, which we have named SNRP-27, suppresses e936 uncoordination through changes in splicing. We propose that SMU-2, SMU-1, and SNRP-27 contribute to the fidelity of splice site choice after the initial identification of 5' splice sites by U1 snRNP.

Asunto(s)

Proteínas de Caenorhabditis elegans/genética , Proteínas del Tejido Nervioso/genética , Sitios de Empalme de ARN/genética , Proteínas Represoras/genética , Empalmosomas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiología , Mapeo Cromosómico , Femenino , Péptidos y Proteínas de Señalización Intracelular , Masculino , Datos de Secuencia Molecular , Actividad Motora/genética , Actividad Motora/fisiología , Mutación , Proteínas Nucleares/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ribonucleoproteína Nuclear Pequeña U1/genética , Ribonucleoproteínas Nucleares Pequeñas/genética , Homología de Secuencia de Aminoácido , Supresión Genética