Stable tri-snRNP integration is accompanied by a major structural rearrangement of the spliceosome that is dependent on Prp8 interaction with the 5' splice site.
RNA
; 21(11): 1993-2005, 2015 Nov.
Article
in En
| MEDLINE
| ID: mdl-26385511
ABSTRACT
Exon definition is the predominant initial spliceosome assembly pathway in higher eukaryotes, but it remains much less well-characterized compared to the intron-defined assembly pathway. Addition in trans of an excess of 5'ss containing RNA to a splicing reaction converts a 37S exon-defined complex, formed on a single exon RNA substrate, into a 45S B-like spliceosomal complex with stably integrated U4/U6.U5 tri-snRNP. This 45S complex is compositonally and structurally highly similar to an intron-defined spliceosomal B complex. Stable tri-snRNP integration during B-like complex formation is accompanied by a major structural change as visualized by electron microscopy. The changes in structure and stability during transition from a 37S to 45S complex can be induced in affinity-purified cross-exon complexes by adding solely the 5'ss RNA oligonucleotide. This conformational change does not require the B-specific proteins, which are recruited during this stabilization process, or site-specific phosphorylation of hPrp31. Instead it is triggered by the interaction of U4/U6.U5 tri-snRNP components with the 5'ss sequence, most importantly between Prp8 and nucleotides at the exon-intron junction. These studies provide novel insights into the conversion of a cross-exon to cross-intron organized spliceosome and also shed light on the requirements for stable tri-snRNP integration during B complex formation.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
RNA-Binding Proteins
/
Spliceosomes
/
Ribonucleoprotein, U4-U6 Small Nuclear
/
RNA Splice Sites
Limits:
Humans
Language:
En
Journal:
RNA
Journal subject:
BIOLOGIA MOLECULAR
Year:
2015
Type:
Article
Affiliation country:
Germany