title: Identification of the heptameric Lsm complex that binds U6 snRNA in Trypanosoma brucei.
abstract: Lsm proteins are ubiquitous, multifunctional proteins that are involved in nuclear processing and turnover of many RNAs in eukaryotes. Lsm proteins form two distinct complexes, the Lsm2-8 complex, which binds U6 snRNA, and the Lsm1-7 complex, which governs mRNA degradation. Previously, seven Lsm proteins were identified in Trypanosoma brucei. Two of these proteins were later identified as SSm proteins (specific spliceosomal Sm proteins). In this study, the Lsm proteins (Lsm2 and Lsm5) that bind to U6 snRNA were identified. RNAi silencing and protein purification of TAP-tagged Lsm proteins were used to identify all the components of the trypanosome heptameric Lsm2-8 complex. Localization studies demonstrated that these proteins are found in the nucleus, near the nucleolus. Lsm proteins were not detected in cytoplasmic bodies that were tagged with YFP-Dhh1, which may suggest that in trypanosomes, Lsm-mediated degradation is not confined to such bodies.
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: Shlomo
authors.initials: S
authors.lastname: Cohen
authors.forename: Mali
authors.initials: M
authors.lastname: Salmon-Divon
authors.forename: Shulamit
authors.initials: S
authors.lastname: Michaeli
mesh_terms: D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D030561:Databases, Nucleic Acid; D008830:Microbodies / Q000737:chemistry; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000302:isolation & purification*; D010957:Plasmids; D034622:RNA Interference; D016053:RNA, Protozoan / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D016053:RNA, Protozoan; D012342:RNA, Small Nuclear; C405486:U6 small nuclear RNA