Identification of a nuclear protein in Trypanosoma brucei with homology to RNA-binding proteins from cis-splicing systems.
Gene expression in trypanosomes is controlled at the level of pre-mRNA maturation via trans-splicing and polyadenylation and through changes in mRNA stability. To identify the trans- acting factors involved in this regulation, we have used a degenerate PCR approach to clone genes encoding the RNA recognition motif (RRM) consensus. We have identified a single-copy gene encoding a protein (designated RRM1) which contains three consensus RRM motifs, two tandem copies of a retroviral gag-like CCHC 'zinc finger' and an arginine-serine (RS) rich region. Western blotting indicates that RRM1 is expressed in both procyclic and bloodstream-form trypanosomes and has an apparent mobility on SDS-PAGE of ca. 70 Kd. RRM1 is localized in the trypanosome nucleus in substructures which may be functionally analogous to the 'speckles' associated with cis-splicing in higher eukaryotic cells. The structure of RRM1, its pattern of expression and its intracellular location suggest that it may play a role in trans-splicing.
Manger
I D
ID
Dept. of Microbiology & Immunology, Stanford University Medical Center, CA 94305-5124, USA.
Boothroyd
J C
JC
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D019084:Fluorescent Antibody Technique, Indirect; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics*; D016053:RNA, Protozoan / Q000032:analysis; D016601:RNA-Binding Proteins / Q000032:analysis / Q000235:genetics*; D016415:Sequence Alignment; D020040:Trans-Splicing / Q000235:genetics*; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000235:genetics*
D009687:Nuclear Proteins; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D016601:RNA-Binding Proteins; C117851:RRM1 protein, Trypanosoma brucei