title: A Trypanosoma brucei protein complex that binds G-overhangs and co-purifies with telomerase activity.
abstract: The chromosomal ends of Trypanosoma brucei, like those of most eukaryotes, contain conserved 5'-TTAGGG-3' repeated sequences and are maintained by the action of telomerase. Fractionated T. brucei cell extracts with telomerase activity were used as a source of potential regulatory factors or telomerase-associated components that might interact with T. brucei telomeres. Electrophoretic mobility shift assays and UV cross-linking were used to detect possible single-stranded telomeric protein.DNA complexes and to estimate the approximate size of the protein constituents. Three single-stranded telomeric protein.DNA complexes were observed. Complex C3 was highly specific for the G-strand telomeric repeat sequence and shares biochemical characteristics with G-rich, single-stranded telomeric binding proteins and with components of the telomerase holoenzyme described in yeast, ciliates, and humans. Susceptibility to RNase A or chemical nuclease (hydroxyl radical) pre-treatment showed that complex C3 was tightly associated with an RNA component. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry was used to estimate the molecular mass of the peptides obtained by in-gel Lys-C digestion of low abundance C3-associated proteins. The molecular masses of the peptides showed no homologies with other proteins from trypanosomes or with any protein in the data bases screened.
authors.affiliation: Department of Stomatology, University of California, San Francisco, California 94143-0422, USA. micano@unicamp.br
authors.forename: Maria Isabel N
authors.initials: MI
authors.lastname: Cano
authors.forename: Julie Johnson
authors.initials: JJ
authors.lastname: Blake
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Blackburn
authors.forename: Nina
authors.initials: N
authors.lastname: Agabian
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D009841:Oligonucleotides / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D019098:Telomerase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009841:Oligonucleotides; D015800:Protozoan Proteins; D012313:RNA; D004247:DNA; D019098:Telomerase