Arabidopsis POT1 associates with the telomerase RNP and is required for telomere maintenance

• Published in: The EMBO journal Vol. 26; no. 15; pp. 3653 - 3661
• Main Authors: Surovtseva, Y.V, Shakirov, E, Vespa, L, Osbun, N, Song, X, Shippen, D.E
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 08-08-2007; Blackwell Publishing Ltd; Nature Publishing Group
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Base Sequence; Botany; Cellular biology; Deoxyribonucleic acid; DNA; DNA Primers; G-overhang; Genomic Instability; Genomics; Molecular biology; Mutation; OB-fold; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleoproteins - metabolism; Telomere; Telomere-Binding Proteins - genetics; Telomere-Binding Proteins - metabolism; TRAP; Yeasts
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7601792

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.