Amino acid changes in Xrs2p, Dun1p, and Rfa2p that remove the preferred targets of the ATM family of protein kinases do not affect DNA repair or telomere length in Saccharomyces cerevisiae.
In eukaryotes, mutations in a number of genes that affect DNA damage checkpoints or DNA replication also affect telomere length [Curr. Opin. Cell Biol. 13 (2001) 281]. Saccharomyces cerevisae strains with mutations in the TEL1 gene (encoding an ATM-like protein kinase) have very short telomeres, as do strains with mutations in XRS2, RAD50, or MRE11 (encoding members of a trimeric complex). Xrs2p and Mre11p are phosphorylated in a Tel1p-dependent manner in response to DNA damage [Genes Dev. 15 (2001) 2238; Mol. Cell 7 (2001) 1255]. We found that Xrs2p, but not Mre11p or Rad50p, is efficiently phosphorylated in vitro by immunopreciptated Tel1p. Strains with mutations eliminating all SQ and TQ motifs in Xrs2p (preferred targets of the ATM kinase family) had wild-type length telomeres and wild-type sensitivity to DNA damaging agents. We also showed that Rfa2p (a subunit of RPA) and the Dun1p checkpoint kinase, which are required for DNA damage repair and which are phosphorylated in response to DNA damage in vivo, are in vitro substrates of the Tel1p and Mec1p kinases. In addition, Dun1p substrates with no SQ or TQ motifs are phosphorylated by Mec1p in vitro very inefficiently, but retain most of their ability to be phosphorylated by Tel1p. We demonstrated that null alleles of DUN1 and certain mutant alleles of RFA2 result in short telomeres. As observed with Xrs2p, however, strains with mutations of DUN1 or RFA2 that eliminate SQ motifs have no effect on telomere length or DNA damage sensitivity.
Mallory
Julia C
JC
Department of Biology and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.
Bashkirov
Vladimir I
VI
Trujillo
Kelly M
KM
Solinger
Jachen A
JA
Dominska
Margaret
M
Sung
Patrick
P
Heyer
Wolf Dietrich
WD
Petes
Thomas D
TD
D000596:Amino Acids; D018797:Cell Cycle Proteins; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids; D011233:Precipitin Tests; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D051716:Replication Protein A; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D016615:Telomere / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic
D000596:Amino Acids; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C086930:RAD50 protein, S cerevisiae; C082727:RFA2 protein, S cerevisiae; D051716:Replication Protein A; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C086929:XRS2 protein, S cerevisiae; D011494:Protein Kinases; C104169:DUN1 protein, S cerevisiae; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae