Characterization of Sm-like proteins in yeast and their association with U6 snRNA.
Seven Sm proteins associate with U1, U2, U4 and U5 spliceosomal snRNAs and influence snRNP biogenesis. Here we describe a novel set of Sm-like (Lsm) proteins in Saccharomyces cerevisiae that interact with each other and with U6 snRNA. Seven Lsm proteins co-immunoprecipitate with the previously characterized Lsm4p (Uss1p) and interact with each other in two-hybrid analyses. Free U6 and U4/U6 duplexed RNAs co-immunoprecipitate with seven of the Lsm proteins that are essential for the stable accumulation of U6 snRNA. Analyses of U4/U6 di-snRNPs and U4/U6.U5 tri-snRNPs in Lsm-depleted strains suggest that Lsm proteins may play a role in facilitating conformational rearrangements of the U6 snRNP in the association-dissociation cycle of spliceosome complexes. Thus, Lsm proteins form a complex that differs from the canonical Sm complex in its RNA association(s) and function. We discuss the possible existence and functions of alternative Lsm complexes, including the likelihood that they are involved in processes other than pre-mRNA splicing.
Mayes
A E
AE
Institute of Cell and Molecular Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
Verdone
L
L
Legrain
P
P
Beggs
J D
JD
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D017411:Ribonucleoproteins, Small Nuclear