Characterization of telomere-binding activity of replication factor C large subunit p140.
The large subunit of RFC (RFC p140) has been suggested to be associated with the 3'-end of elongating DNA primer and to recruit proliferating cell nuclear antigen (PCNA) onto DNA polymerase delta. Previously, we isolated a cDNA clone encoding a DNA-binding domain of RFC p140 as a telomeric repeat (TTAGGG)n binding protein. This domain was shown to have a specific affinity for the 5'-phosphate ends of a telomere repeat sequence. In order to investigate the structure and function of RFC p140, we constructed the full-length recombinant RFC p140 as well as N- and/or C-terminal deleted mutants and analyzed their telomere-binding activities. South-Western blot and gel mobility shift analyses revealed that deletion of the N- but not the C-terminal region enhances recognition of the telomeric repeat sequence and 5'-phosphate ends, suggesting the negative effect of the N-terminal region of the RFC p140 binding to the telomeric repeat. On the other hand, the C-terminal truncated RFC inhibits the telomerase activity more than the N-terminal-deleted and full-length RFC p140. The inhibitory effect of RFC p140 on telomerase activity is completely diminished by both terminal deletions. Thus, a certain interaction of the N- and C-terminal regions is considered to be required for RFC p140 to suppress telomerase activity. Taken together, these results suggest that both telomeric repeat-binding and telomerase inhibitory activities of RFC p140 are finely regulated by the intrinsic N- and C-terminal regions.
D000375:Aging / Q000235:genetics; D001483:Base Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D018398:Homeodomain Proteins; D006801:Humans; D019169:Jurkat Cells; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D051818:Replication Protein C; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D019098:Telomerase / Q000037:antagonists & inhibitors; D016615:Telomere