Table 1  Major genes affecting Saccharomyces cerevisiae telomeres
Gene nameaa/MW (KD)Essential (yes/no)Function(s)a
Structural proteins
RAP1827/92.4YesSequence-specific double-strand DNA binding telomere capping and length regulation, TPE, major transcription factor.
CDC13Cdc 13 complex924/104.9YesThree-protein complex comprised of Cdc13p, Stn1p, and Ten1p, which binds single-strand TG1-3 DNA in sequence-specific manner, capping, telomerase recruitment.
STN1494/57.5No
TEN1160/18.6No
RIF11916/217.9NoInteracts w. Rap1p; telomerase regulator.
RIF2395/45.6NoInteracts w. Rap1p; telomerase regulator, capping.
YKU70YKu complex602/70.6NoInteracts w. TLC1; telomere length regulation; capping; TPE; telomere positioning; nonhomologous end joining.
YKU80629/71.2No
SIR2562/63.2NoInteract w. Sir4p; essential for TPE and HM silencing, histone deacetylase.
SIR3978/111.3NoInteracts with w. Rap1p, Sir4p, histone tails; essential for TPE and HM silencing.
SIR41358/152.0NoInteracts with Yku80p, Sir2p, Rap1p, and histone tails; essential for TPE and HM silencing; telomere positioning.
TBF1562/62.8YesTPE boundary function, telomerase recruitment to short telomeres; transcription factor.
NDJ1352/40.8NoMeiosis specific, telomere binding, essential for bouquet formation.
Telomere replication
EST1699/81.7NoProtein subunit of telomerase; recruitment, activation.
EST2884/102.6NoProtein subunit of telomerase; catalytic reverse transcriptase.
EST3181/20.5NoProtein subunit of telomerase.
TLC11157 ntNoTelomerase RNA; repeat templating.
PIF1859/87.6NoDNA helicase, removes telomerase from DNA, also required for maintenance of mitochondrial and nontelomeric nuclear DNA.
TEL12787/321.5NoInteracts w. Xrs2p, telomere length regulation; telomerase recruitment; S phase checkpoint kinase.
MRE11MRX Complex692/77.6NoActs as complex in same pathway as TEL1; recruits telomerase; required for type II survivors and other homologous recombination events; Mre 11p is a nuclease, Rad50p has ATPase and DNA binding activity; Xrs2p interacts with Tel1p.
RAD501312/152.5
XRS2854/96.3
MEC12368/273.3YesMajor DNA damage checkpoint kinase; partially redundant function with Tel1p in telomerase recruitment; activated when very short or no telomere; mec1Δ sml1Δ cells are viable but deficient for both telomere and checkpoint functions of Mec1p
RRM3723/81.5NoDNA helicase, semiconservative telomere replication; promotes replication at many nontelomeric sites.
Processing and recombination
SGS11447/163.8NoDNA helicase, end processing DSBs and telomeres, required for type II survivors; rDNA recombination.
RAD52471/52.4NoEssential for all homologous recombination, including type I and type II survivors.
RAD51400/42.9NoHomologous recombination, required for type I survivors.
SAE2345/40.0No5′ strand resection at DSBs and telomeres.
EXO1702/80.1NoNuclease, 5′ end resection at DSBs and telomeres.
DNA21522/171.6YesHelicase-nuclease; 5′ end resection at telomeres and DSBs; Okazaki fragment maturation.
POL32350/40.3NoSubunit of DNA pol δ; required for break-induced replication and both type I and type II survivors.
  • a See text for details and references; although many genes are involved in more than one process, each is listed here under only one heading. Essential/nonessential refers to viability, not telomere maintenance. aa, number of amino acids; MW sizes are from the SGD website http:/www.yeastgenome.org/.