A spliceosome intermediate with loosely associated tri-snRNP accumulates in the absence of Prp28 ATPase activity.

ABSTRACT: The precise role of the spliceosomal DEAD-box protein Prp28 in higher eukaryotes remains unclear. We show that stable tri-snRNP association during pre-catalytic spliceosomal B complex formation is blocked by a dominant-negative hPrp28 mutant lacking ATPase activity. Complexes formed in the presence of ATPase-deficient hPrp28 represent a novel assembly intermediate, the pre-B complex, that contains U1, U2 and loosely associated tri-snRNP and is stalled before disruption of the U1/5'ss base pairing interaction, consistent with a role for hPrp28 in the latter. Pre-B and B complexes differ structurally, indicating that stable tri-snRNP integration is accompanied by substantial rearrangements in the spliceosome. Disruption of the U1/5'ss interaction alone is not sufficient to bypass the block b

SUBMITTER: Boesler C 

PROVIDER: S-EPMC4935976 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature