RecA-Dependent Mechanisms for the Generation of Genetic Diversity

Abstract

This chapter discusses the roles of RecA and other proteins in homologous recombination. It also focuses on RecA's other roles, as these also contribute to increases in genetic diversity. It discusses how homologous recombination occurs at the molecular level and how this can lead to an increase in genetic diversity. It summarizes the current understanding of recA's crucial and essential role in homologous recombination, its other roles in the regulation of damage-inducible DNA-repair pathways, and its participation in mutagenic events that can lead to increases in genetic diversity. It is most convenient to think of recombination as a three-stage process. The three stages are called presynapsis, synapsis, and postsynapsis. These stages are used to discuss the processing of the DNA substrates and the enzymes that act on them. Presynapsis describes the tailoring of the DNA substrates so that they can interact with the RecA protein. If the recombination enzymes and substrates are present, the enzymes will recombine any DNA that is available with great accuracy, precision, and efficiency. The prevailing thought in the chapter is that once recombination substrates are presented to a cell, given that the cell has the proper enzymes, recombination will occur. RecA aids in the repair of double-strand breaks in DNA.