Telomere-binding Proteins from Nuclei of Telmerase-negative Tissues Inhibit Plant Telomerase
We have previously shown, that in plant cells, similarly to human, animal and protozoan cells, telomeres are maintained by telomerase, the specialised ribonucleoprotein complex of reverse-transcriptase activity. Our subsequent studies revealed the conservation of telomere lengths in various plant tissues and during plant development. The activity of telomerase in plant cells is precisely regulated in response to changes in cell division rate. To explore this regulatory mechanism, the effect on telomerase activity of protein extracts from nuclei of telomerase-negative tissues was examined. An inhibition of telomerase activity was found which was species-nonspecific. This inhibition was due to proteins which form salt-stable, sequence specific complexes with the G-rich telomeric strand and reduce its accessibility, as shown by gel retardation and by terminal transferase (TdT) extension of G-rich telomeric and non-telomeric (substrate) primers. A 40 kDa polypeptide was detected by SDS-PAGE after cross-linking the complex formed by extracts from tobacco leaf nuclei. Such proteins may be involved in regulation of telomerase activity in plants.
This work was supported by grant no. VS97032 from the Czech Ministry of Education.
J. Fulneckova1 and Jiri Fajkus1,2
1 Department of Analysis of Biologically Important Molecular Complexes,