Role of recombination enzymes in mammalian cell survival.

Abstract

Recombination between homologous DNA sequences occurs in all organisms and the exchange of information is critical for the survival of the species. Homologous recombination provides an effective means of generating genomic diversity that is so important for the evolution of different species. In higher organisms, chromosome pairing and recombination events occur in meiosis and there is a significant amount of information to the effect that failure of these processes would lead to abnormal chromosomal segregation. Therefore, it is conceivable that mutations in critical genes involved in meiotic recombination in mammals would lead to abnormalities in meiosis leading to the failure of such animals to reproduce properly. In this issue, Tsuzuki and colleagues (1) report on the generation of mice that are heterozygous for a null mutation in the Rad5l gene. When the heterozygotes are interbred, they fail to produce mice that are homozygous for the mutation. They also show that embryos that are RadS1 deficient die at the earliest stages of development and they propose that the Rad5l gene product is essential for somatic cell growth and survival. We will briefly review the properties of recombination proteins in different organisms and discuss the significance of the observations reported by Tsuzuki et al. (1).