Human step II splicing factor hSlu7 functions in restructuring the spliceosome between the catalytic steps of splicing.
The spliceosome catalyzes pre-mRNA splicing in two steps. After catalytic step I, a major remodeling of the spliceosome occurs to establish the active site for step II. Here, we report the isolation of a cDNA encoding hSlu7, the human homolog of the yeast second step splicing factor Slu7. We show that hSlu7 associates with the spliceosome late in the splicing pathway, but at a stage prior to recognition of the 3' splice site for step II. In the absence of hSlu7, splicing is stalled between the catalytic steps in a novel complex, the CDeltahSlu7 complex. We provide evidence that this complex differs significantly in structure from the known spliceosomal complexes, yet is a functional intermediate between the catalytic steps of splicing. Together, our observations indicate that hSlu7 is required for a structural alteration of the spliceosome prior to the establishment of the catalytically active spliceosome for step II.
Chua
K
K
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115 USA.
Reed
R
R
D000256:Adenoviridae / Q000235:genetics; D000595:Amino Acid Sequence; D015153:Blotting, Western; D020224:Expressed Sequence Tags; D051717:Fushi Tarazu Transcription Factors; D005914:Globins / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D012326:RNA Splicing / Q000502:physiology*; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*; D013997:Time Factors; D014335:Tropomyosin / Q000378:metabolism
D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; C490656:SLU7 protein, human; D014335:Tropomyosin; D005914:Globins