While most Solanaceae genera (e.g.Solanum, Nicotiana) possess Arabidopsis-type telomeres of (TTTAGGG)n maintained by telomerase, the genera Cestrum, Vestia and Sessea (Cestrum group) lack these telomeres. Here we show that in the Cestrum-group the activity of telomerase has been lost. Nevertheless, proteins binding the single-stranded G-rich strand of the Arabidopsis-type and related human-type (TTAGGG)n telomeric sequences are present in nuclear extracts of both Nicotiana and Cestrum species. These proteins may have a role in telomere function or other cellular activities. In addition to characterizing DNA binding specificity and molecular weights of these proteins, we searched in both N. tabacum (tobacco) and C. parqui for the presence of POT1-like proteins, involved in telomere capping and telomerase regulation. Analysis of POT1-like proteins available on public databases and cloned by us from C. parqui, revealed the N-terminal OB folds typical for this protein family and a novel, plant-specific conserved C-terminal OB-fold domain (CTOB). We propose that CTOB is involved in protein-protein interactions.

Institute of Biophysics Czech Academy of Sciences Masaryk University Brno Czech Republic

References provided by Crossref.org

Origin, Diversity, and Evolution of Telomere Sequences in Plants

Telomere- and Telomerase-Associated Proteins and Their Functions in the Plant Cell

Transitions between the Arabidopsis-type and the human-type telomere sequence in green algae (clade Caudivolvoxa, Chlamydomonadales)

Distribution of TTAGG-specific telomerase activity in insects

Telomere repeat binding proteins are functional components of Arabidopsis telomeres and interact with telomerase

Dynamic evolution of telomeric sequences in the green algal order Chlamydomonadales