The REC1 gene of Ustilago maydis, which encodes a 3'-->5' exonuclease, couples DNA repair and completion of DNA synthesis to a mitotic checkpoint. Academic Article uri icon

Overview

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.

publication date

  • May 1, 1996

Research

keywords

  • DNA Repair
  • DNA Replication
  • Exodeoxyribonucleases
  • Fungal Proteins
  • Ustilago

Identity

PubMed Central ID

  • PMC1207251

Scopus Document Identifier

  • 0029931882

PubMed ID

  • 8722772

Additional Document Info

volume

  • 143

issue

  • 1