Requirements for U2 snRNP addition to yeast pre-mRNA.

AUTOR(ES)

Liao, X C

RESUMO

The in vitro spliceosome assembly pathway is conserved between yeast and mammals as U1 and U2 snRNPs associate with the pre-mRNA prior to U5 and U4/U6 snRNPs. In yeast, U1 snRNP-pre-mRNA complexes are the first splicing complexes visualized on native gels, and association with U1 snRNP apparently commits pre-mRNA to the spliceosome assembly pathway. The current study addresses U2 snRNP addition to commitment complexes. We show that commitment complex formation is relatively slow and does not require ATP, whereas U2 snRNP adds to the U1 snRNP complexes in a reaction that is relatively fast and requires ATP or hydrolyzable ATP analogs. In vitro spliceosome assembly was assayed in extracts derived from strains containing several U1 sRNA mutations. The results were consistent with a critical role for U1 snRNP in early complex formation. A mutation that disrupts the base-pairing between the 5' end of U1 snRNA and the 5' splice site allows some U2 snRNP addition to bypass the ATP requirement, suggesting that ATP may be used to destabilize certain U1 snRNP:pre-mRNA interactions to allow subsequent U2 snRNP addition.

Documentos Relacionados

• Interplay between U2 snRNP and 3' splice factor(s) for branch point selection on human beta-globin pre-mRNA.
• A novel U2 and U11/U12 snRNP protein that associates with the pre-mRNA branch site
• Antisense probes targeted to an internal domain in U2 snRNP specifically inhibit the second step of pre-mRNA splicing.
• Biochemical characterization of U2 snRNP auxiliary factor: an essential pre-mRNA splicing factor with a novel intranuclear distribution.
• Crosslinking of hnRNP proteins to pre-mRNA requires U1 and U2 snRNPs.