title: Arabidopsis POT1 associates with the telomerase RNP and is required for telomere maintenance.
abstract: POT1 is a single-copy gene in yeast and humans that encodes a single-strand telomere binding protein required for chromosome end protection and telomere length regulation. In contrast, Arabidopsis harbors multiple, divergent POT-like genes that bear signature N-terminal OB-fold motifs, but otherwise share limited sequence similarity. Here, we report that plants null for AtPOT1 show no telomere deprotection phenotype, but rather exhibit progressive loss of telomeric DNA. Genetic analysis indicates that AtPOT1 acts in the same pathway as telomerase. In vitro levels of telomerase activity in pot1 mutants are significantly reduced and are more variable than wild-type. Consistent with this observation, AtPOT1 physically associates with active telomerase particles. Although low levels of AtPOT1 can be detected at telomeres in unsynchronized cells and in cells arrested in G2, AtPOT1 binding is significantly enhanced during S-phase, when telomerase is thought to act at telomeres. Our findings indicate that AtPOT1 is a novel accessory factor for telomerase required for positive telomere length regulation, and they underscore the coordinate and extraordinarily rapid evolution of telomere proteins and the telomerase enzyme.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128, USA.
authors.forename: Yulia V
authors.initials: YV
authors.lastname: Surovtseva
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Shakirov
authors.forename: Laurent
authors.initials: L
authors.lastname: Vespa
authors.forename: Nathan
authors.initials: N
authors.lastname: Osbun
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Song
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Shippen
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D042822:Genomic Instability; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000378:metabolism*; D000089804:Shelterin Complex; D016615:Telomere; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; C503876:Pot1 protein, Arabidopsis; D012261:Ribonucleoproteins; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins