Premium
Taz1, Rap1 and Rif1 act both interdependently and independently to maintain telomeres
Author(s) -
Miller Kyle M,
Ferreira Miguel Godinho,
Cooper Julia Promisel
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600779
Subject(s) - telomere , biology , telomere binding protein , rap1 , function (biology) , genetics , microbiology and biotechnology , chromosome , telomerase , dna , chromosome segregation , dna binding protein , gene , transcription factor
Telomere protection and maintenance are accomplished through the coordinated actions of telomere‐specific DNA binding proteins and their interacting partners. The fission yeast ortholog of human TRF1/2, Taz1, binds telomeric DNA and regulates numerous aspects of telomere function. Here, we ask which aspects of Taz1 function are mediated through its interacting proteins, Rap1 and Rif1. We demonstrate that rap1 + deletion phenocopies some, but not all, aspects of taz1 Δ telomere dysfunction, while Rif1 exhibits a very different functional spectrum. Rap1 acts in a Taz1‐dependent pathway to prevent chromosome end fusions and regulate telomeric 3′ overhang formation, while Rif1 is dispensable for these functions. Telomerase inhibition by Taz1 is mediated by two separate pathways, one involving Rap1 and the other involving Rif1. In contrast, Taz1 is uniquely required to prevent chromosomal entanglements and missegregation at cold temperatures. Strikingly, while rap1 + deletion exacerbates the cold sensitivity of taz1 Δ cells, rif1 + deletion restores full viability. Thus, Rap1 and Rif1 are each required for a subset of the functions of Taz1, but each acquires Taz1‐independent functions in its absence. Furthermore, Taz1 can function independently of its known binding partners.