title: Identification of novel snRNA-specific Sm proteins that bind selectively to U2 and U4 snRNAs in Trypanosoma brucei.
abstract: In eukaryotes the seven Sm core proteins bind to U1, U2, U4, and U5 snRNAs. In Trypanosoma brucei, Sm proteins have been implicated in binding both spliced leader (SL) and U snRNAs. In this study, we examined the function of these Sm proteins using RNAi silencing and protein purification. RNAi silencing of each of the seven Sm genes resulted in accumulation of SL RNA as well as reduction of several U snRNAs. Interestingly, U2 was unaffected by the loss of SmB, and both U2 and U4 snRNAs were unaffected by the loss of SmD3, suggesting that these snRNAs are not bound by the heptameric Sm complex that binds to U1, U5, and SL RNA. RNAi silencing and protein purification showed that U2 and U4 snRNAs were bound by a unique set of Sm proteins that we termed SSm (specific spliceosomal Sm proteins). This is the first study that identifies specific core Sm proteins that bind only to a subset of spliceosomal snRNAs.
authors.affiliation: The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Itai Dov
authors.initials: ID
authors.lastname: Tkacz
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Lustig
authors.forename: Michael Zeev
authors.initials: MZ
authors.lastname: Stern
authors.forename: Moshe
authors.initials: M
authors.lastname: Biton
authors.forename: Mali
authors.initials: M
authors.lastname: Salmon-Divon
authors.forename: Anish
authors.initials: A
authors.lastname: Das
authors.forename: Vivian
authors.initials: V
authors.lastname: Bellofatto
authors.forename: Shulamit
authors.initials: S
authors.lastname: Michaeli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019295:Computational Biology; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016053:RNA, Protozoan / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D016053:RNA, Protozoan; D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C405484:U2 small nuclear RNA; C405482:U4 small nuclear RNA