Interactions of putative telomere-binding proteins in Arabidopsis thaliana: identification of functional TRF2 homolog in plants.
Telomere-binding proteins are required for forming the functional structure of chromosome ends and regulating telomerase action. Although a number of candidate proteins have been identified by homology searches to plant genome databases and tested for their affinity to telomeric DNA sequences in vitro, there are minimal data relevant to their telomeric function. To address this problem, we made a collection of cDNAs of putative telomere-binding proteins of Arabidopsis thaliana to analyse their protein-protein interactions with the yeast two-hybrid system. Our results show that one myb-like protein, AtTRP1, interacts specifically with AtKu70, the latter protein having a previously described role in plant telomere metabolism. In analogy to the interaction between human Ku70 and TRF2 proteins, our results suggest that AtTRP1 is a likely homolog of TRF2. The AtTRP1 domain responsible for AtKu70 interaction occurs between amino acid sequence positions 80 and 269. The protein AtTRB1, a member of the single myb histone (Smh) family, shows self-interaction and interactions to the Smh family proteins AtTRB2 and AtTRB3. Protein AtTRB1 also interacts with AtPot1, the Arabidopsis homolog of oligonucleotide-binding-fold-containing proteins which bind G-rich telomeric DNA. In humans, the TRF1-complex recruits hPot1 to telomeres by protein-protein interactions where it is involved in telomere length regulation. Possibly, AtTRB1 has a similar role in recruiting AtPot1.
Kuchar
Milan
M
Department of Functional Genomics and Proteomics, Masaryk University Brno, Kotlárská 2, CZ-611 37 Brno, Czech Republic.
Fajkus
Jirí
J
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001345:Autoradiography; D001665:Binding Sites; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008715:Methionine / Q000737:chemistry; D016366:Open Reading Frames; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D013462:Sulfur Radioisotopes; D016615:Telomere; D034501:Telomere-Binding Proteins / Q000378:metabolism*; D035341:Telomeric Repeat Binding Protein 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D010940:Plant Proteins; D013462:Sulfur Radioisotopes; D034501:Telomere-Binding Proteins; D035341:Telomeric Repeat Binding Protein 2; D008715:Methionine