Hed1 regulates Rad51-mediated recombination via a novel mechanism.

Two RecA orthologs, Rad51 and Dmc1, mediate homologous recombination in meiotic cells. During budding yeast meiosis, Hed1 coordinates the actions of Rad51 and Dmc1 by down-regulating Rad51 activity. It is thought that Hed1-dependent attenuation of Rad51 facilitates formation of crossovers that are necessary for the correct segregation of chromosomes at the first meiotic division.

A defect in the acetyl coenzyme A<-->acetate pathway poisons recombinational repair-deficient mutants of Escherichia coli.

Recombinational repair-dependent mutants identify ways to avoid chromosomal lesions. Starting with a recBC(Ts) strain of Escherichia coli, we looked for mutants unable to grow at 42 degrees C in conditions that inactivate the RecBCD(Ts) enzyme. We isolated insertions in ackA and pta, which comprise a two-gene operon responsible for the acetate<-->acetyl coenzyme A interconversion.