ST-1, a 39-kilodalton protein in Trypanosoma brucei, exhibits a dual affinity for the duplex form of the 29-base-pair subtelomeric repeat and its C-rich strand.
In our attempt to identify telomere region-binding proteins in Trypanosoma brucei, we identified ST-1, a polypeptide with novel features. ST-1 was chromatographically purified from S-100 cell extracts and was renatured from a sodium dodecyl sulfate-protein gel as a 39-kDa polypeptide. It forms a specific complex with the trypanosome telomere repeats of TTAGGG, but more significantly, it shows a higher affinity for the 29-bp subtelomere repeats of T. brucei. These 29-mer boxes are a large tandem series of telomere-derived repeats which separate the simple telomere DNA from middle-repetitive telomere-associated sequences on many chromosomes. ST-1 is the first example of a protein binding within such large repetitive subtelomere elements in trypanosomes or other organisms. ST-1 is also novel in that it has a selective affinity for the C-rich strands of both the subtelomeric 29-mer and the telomere repeats, comparable to that for the duplex form of the respective repeats. All previously described telomere-binding proteins have affinity for only the duplex form or for the G-rich strand. This C-rich strand binding specificity of ST-1 may provide insight into this protein's mechanism of binding in vivo.
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Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Sollner-Webb
B
B
D000818:Animals; D001483:Base Sequence; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D016615:Telomere / Q000378:metabolism*; D014346:Trypanosoma brucei brucei
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D015800:Protozoan Proteins