Title | The REC1 gene of Ustilago maydis, which encodes a 3'-->5' exonuclease, couples DNA repair and completion of DNA synthesis to a mitotic checkpoint. |
Publication Type | Journal Article |
Year of Publication | 1996 |
Authors | Onel K, Koff A, Bennett RL, Unrau P, Holloman WK |
Journal | Genetics |
Volume | 143 |
Issue | 1 |
Pagination | 165-74 |
Date Published | 1996 May |
ISSN | 0016-6731 |
Keywords | Base Sequence, Cell Cycle, DNA Damage, DNA Primers, DNA Repair, DNA Replication, DNA, Fungal, Exodeoxyribonuclease V, Exodeoxyribonucleases, Fungal Proteins, Kinetics, Mitosis, Molecular Sequence Data, Mutagenesis, Site-Directed, Polymerase Chain Reaction, Time Factors, Ultraviolet Rays, Ustilago |
Abstract | Mutation in the REC1 gene of Ustilago maydis results in extreme sensitivity to killing by ultraviolet light. The lethality of the rec1-1 mutant was found to be partially suppressed if irradiated cells were held artificially in G2-phase by addition of a microtubule inhibitor. This mutant was also found to be sensitive to killing when DNA synthesis was inhibited by external means through addition of hydroxyurea or by genetic control in a temperature-sensitive mutant strain defective in DNA synthesis. Flow cytometric analysis of exponentially growing cultures indicated that wild-type cells accumulated in G2 after UV irradiation, while rec1-1 cells appeared to exit from G2 and accumulate in G1/S. Analysis of mRNA levels in synchronized cells indicated that the REC1 gene is periodically expressed with the cell cycle and reaches maximal levels at G1/S. The results are interpreted to mean that a G2-M checkpoint is disabled in the rec1-1 mutant. It is proposed that the REC1 gene product functions in a surveillance system operating during S-phase and G2 to find and repair stretches of DNA with compromised integrity and to communicate with the cell cycle apparatus. |
Alternate Journal | Genetics |
PubMed ID | 8722772 |
PubMed Central ID | PMC1207251 |
Grant List | GM-42482 / GM / NIGMS NIH HHS / United States |
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