Schmidt TT~Hombauer H, 2020

Pubmed ID 31647103
Title Inactivation of folylpolyglutamate synthetase Met7 results in genome instability driven by an increased dUTP/dTTP ratio.
Authors Tobias T Schmidt, Sushma Sharma, Gloria X Reyes, Anna Kolodziejczak, Tina Wagner, Brian Luke, Anders Hofer, Andrei Chabes, Hans Hombauer
Abstract The accumulation of mutations is frequently associated with alterations in gene function leading to the onset of diseases, including cancer. Aiming to find novel genes that contribute to the stability of the genome, we screened the Saccharomyces cerevisiae deletion collection for increased mutator phenotypes. Among the identified genes, we discovered MET7, which encodes folylpolyglutamate synthetase (FPGS), an enzyme that facilitates several folate-dependent reactions including the synthesis of purines, thymidylate (dTMP) and DNA methylation. Here, we found that Met7-deficient strains show elevated mutation rates, but also increased levels of endogenous DNA damage resulting in gross chromosomal rearrangements (GCRs). Quantification of deoxyribonucleotide (dNTP) pools in cell extracts from met7Δ mutant revealed reductions in dTTP and dGTP that cause a constitutively active DNA damage checkpoint. In addition, we found that the absence of Met7 leads to dUTP accumulation, at levels that allowed its detection in yeast extracts for the first time. Consequently, a high dUTP/dTTP ratio promotes uracil incorporation into DNA, followed by futile repair cycles that compromise both mitochondrial and nuclear DNA integrity. In summary, this work highlights the importance of folate polyglutamylation in the maintenance of nucleotide homeostasis and genome stability.
Citation Nucleic Acids Res. 2020; 48:264-277

Datasets

Download the list of datasets
Paper Phenotype Condition Medium Collection Tested mutants Data Details
Schmidt TT~Hombauer H, 2020 mutation frequency (CanR) standard hap a (post-SGA) ~4,800 Discrete
Schmidt TT~Hombauer H, 2020 (lys2-10A) standard hap a (post-SGA) ~4,800 Discrete

Curation history

Data

July 24, 2020 To add media.
July 24, 2020 To prepare data.

Tested strains

July 24, 2020 To add media.
July 24, 2020 To prepare data.