The splicing regulator TIA-1 interacts with U1-C to promote U1 snRNP recruitment to 5′ splice sites

AUTOR(ES)

Förch, Patrik

FONTE

Oxford University Press

RESUMO

The U1 small nuclear ribonucleoprotein (U1 snRNP) binds to the pre-mRNA 5′ splice site (ss) at early stages of spliceosome assembly. Recruitment of U1 to a class of weak 5′ ss is promoted by binding of the protein TIA-1 to uridine-rich sequences immediately downstream from the 5′ ss. Here we describe a molecular dissection of the activities of TIA-1. RNA recognition motifs (RRMs) 2 and 3 are necessary and sufficient for binding to the pre-mRNA. The non- consensus RRM1 and the C-terminal glutamine-rich (Q) domain are required for association with U1 snRNP and to facilitate its recruitment to 5′ ss. Co-precipitation experiments revealed a specific and direct interaction involving the N-terminal region of the U1 protein U1-C and the Q-rich domain of TIA-1, an interaction enhanced by RRM1. The results argue that binding of TIA-1 in the vicinity of a 5′ ss helps to stabilize U1 snRNP recruitment, at least in part, via a direct interaction with U1-C, thus providing one molecular mechanism for the function of this splicing regulator.

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