Poster: Cell Cycle
Abs #
237: Sequence-specific binding property of Arabidopsis thaliana telomeric DNA binding protein 1(AtTBP1)
In eukaryotic organisms, the telomere is a well-conserved structure that consists of telomeric repeats and specifically associated proteins. The telomere is essential for the maintenance of chromosome integrity and for protection from end-to-end fusion and exonucleolytic degradation. We have identified an Arabidopsis thaliana cDNA, designated as AtTBP1, encoding a protein with a predicted size of 70.6 kDa that specifically binds to the plant telomeric repeat sequence TTTAGGG. AtTBP1 is present as a single copy gene in Arabidopsis genome and is expressed ubiquitously in various organs. AtTBP1 has a single Myb telomeric DNA binding domain at the C-terminus and extensive homology with other known telomere binding proteins. The isolated C-terminus of AtTBP1 is capable of sequence-specific DNA binding to plant duplex telomeric DNA. Two-telomere repeats are minimum length for binding the isolated C-terminus of AtTBP1. Arabidopsis thaliana telomere-associated sequences (TAS) are not able to compete with telomeric repeats in binding to AtTBP1. Experiments with GFP-AtTBP1 in onion epidermal cells reveal that AtTBP1 is a nuclear protein with a functional nuclear localization signal. These results suggest that AtTBP1 may play important roles in plant telomere function in vivo.
