The splicing regulator TIA-1 interacts with U1-C to promote U1 snRNP recruitment to 5' splice sites.
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.
Förch
Patrik
P
Gene Expression Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
Puig
Oscar
O
Martínez
Concepción
C
Séraphin
Bertrand
B
Valcárcel
Juan
J
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D005363:Ficusin / Q000494:pharmacology; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D039102:Poly(A)-Binding Proteins; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D000074019:T-Cell Intracellular Antigen-1; D014466:Ultraviolet Rays
D008565:Membrane Proteins; D039102:Poly(A)-Binding Proteins; D011506:Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D000074019:T-Cell Intracellular Antigen-1; C071558:TIA1 protein, human; D005982:Glutathione Transferase; D016914:Ribonuclease H; D005363:Ficusin