期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 281, 期 22, 页码 15058-15063出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M601968200
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资金
- NCI NIH HHS [CA82633] Funding Source: Medline
- NIEHS NIH HHS [P30 ES00210] Funding Source: Medline
Thioredoxin was initially identified by its ability to serve as an electron donor for ribonucleotide reductase in vitro. Whether it serves a similar function in vivo is unclear. In Saccharomyces cerevisiae, it was previously shown that Delta trx1 Delta trx2 mutants lacking the two genes for cytosolic thioredoxin have a slower growth rate because of a longer S phase, but the basis for S phase elongation was not identified. The hypothesis that S phase protraction was due to inefficient dNTP synthesis was investigated by measuring dNTP levels in asynchronous and synchronized wild-type and Delta trx1 Delta trx2 yeast. In contrast to wild-type cells, Delta trx1 Delta trx2 cells were unable to accumulate or maintain high levels of dNTPs when alpha-factor- or cdc15-arrested cells were allowed to reenter the cell cycle. At 80 min after release, when the fraction of cells in S phase was maximal, the dNTP pools in Delta trx1 Delta trx2 cells were 60% that of wild-type cells. The data suggest that, in the absence of thioredoxin, cells cannot support the high rate of dNTP synthesis required for efficient DNA synthesis during S phase. The results constitute in vivo evidence for thioredoxin being a physiologically relevant electron donor for ribonucleotide reductase during DNA precursor synthesis.
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