Generation of telomeric G strand overhangs involves both G and C strand cleavage.
Processing of telomeric DNA is required to generate the 3' G strand overhangs necessary for capping chromosome ends. We have investigated the steps involved in telomere processing by examining G overhang structure in Tetrahymena cells that lack telomerase or have altered telomeric sequences. We show that overhangs are generated by two precise cleavage steps involving nucleases that are robust but lack sequence specificity. Our data suggest that a G overhang binding protein delineates the boundaries for G and C strand cleavage. We also show that telomerase is not the nuclease responsible for G strand cleavage, although telomerase depletion alters the precision of processing. This change in processing indicates that telomerase affects multiple transactions at the telomere and provides a physical footprint for the continued association of telomerase with the telomere after repeat addition is complete.
Jacob
Naduparambil K
NK
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Ohio 45267, USA.
Kirk
Karen E
KE
Price
Carolyn M
CM
D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D002875:Chromosomes / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism; D018390:Gene Targeting; D023421:Models, Animal; D011401:Promoter Regions, Genetic / Q000235:genetics; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000235:genetics* / Q000378:metabolism; D013768:Tetrahymena / Q000235:genetics* / Q000378:metabolism
D004247:DNA; D019098:Telomerase; D003851:Deoxyribonucleases