A role for SNU66 in maintaining 5' splice site identity during spliceosome assembly.

Autor:	Sarka K; Center for Molecular Biology of RNA and Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, USA., Katzman S; UCSC Genomics Institute, University of California Santa Cruz, Santa Cruz, California 95064, USA., Zahler AM; Center for Molecular Biology of RNA and Department of Molecular, Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, California 95064, USA zahler@ucsc.edu.
Jazyk:	angličtina
Zdroj:	RNA (New York, N.Y.) [RNA] 2024 May 16; Vol. 30 (6), pp. 695-709. Date of Electronic Publication: 2024 May 16.
DOI:	10.1261/rna.079971.124
Abstrakt:	In spliceosome assembly, the 5' splice site is initially recognized by U1 snRNA. U1 leaves the spliceosome during the assembly process, therefore other factors contribute to the maintenance of 5' splice site identity as it is loaded into the catalytic site. Recent structural data suggest that human tri-snRNP 27K (SNRP27) M141 and SNU66 H734 interact to stabilize the U4/U6 quasi-pseudo knot at the base of the U6 snRNA ACAGAGA box in pre-B complex. Previously, we found that mutations in Caenorhabditis elegans at SNRP-27 M141 promote changes in alternative 5'ss usage. We tested whether the potential interaction between SNRP-27 M141 and SNU-66 H765 (the C. elegans equivalent position to human SNU66 H734) contributes to maintaining 5' splice site identity during spliceosome assembly. We find that SNU-66 H765 mutants promote alternative 5' splice site usage. Many of the alternative 5' splicing events affected by SNU-66(H765G) overlap with those affected SNRP-27(M141T). Double mutants of snrp-27(M141T) and snu-66(H765G) are homozygous lethal. We hypothesize that mutations at either SNRP-27 M141 or SNU-66 H765 allow the spliceosome to load alternative 5' splice sites into the active site. Tests with mutant U1 snRNA and swapped 5' splice sites indicate that the ability of SNRP-27 M141 and SNU-66 H765 mutants to affect a particular 5' splice alternative splicing event is dependent on both the presence of a weaker consensus 5'ss nearby and potentially nearby splicing factor binding sites. Our findings confirm a new role for the C terminus of SNU-66 in maintenance of 5' splice site identity during spliceosome assembly. (© 2024 Sarka et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu