Poster Presentation Society for Molecular Biology and Evolution Conference 2016

To convert or not to convert: homology requirements for meiotic gene conversion (#487)

Diego A Hartasánchez 1 , Marina Brasó-Vives 1 , Arcadi Navarro 1
  1. Institute of Evolutionary Biology (Universitat Pompeu Fabra - CSIC), Barcelona, BARCELONA, Spain

Gene conversion is a recombination mechanism in which information is unilaterally transferred from one DNA duplex to another. During meiosis, double-strand-breaks might be repaired by different mechanisms of homologous recombination such as single-strand annealing, double-strand-break repair or synthesis-dependent strand annealing. The latter is thought to be the cause of the large majority of meiotic gene conversion events and extensive experimental work has been performed to understand the precise molecular mechanisms and molecules involved in this pathway.

For gene conversion to occur, there needs to be a high degree of homology between the invading strand of DNA and the invaded donor strand from which complementary DNA will be synthesized. In fact, there seems to be a minimal efficient processing segment, that is, a 100% identity tract between donor and receptor strands, necessary for the gene conversion process to initiate. Further evidence indicates that there might also be an identity requirement for the resolution of the repair pathway. Additionally, experiments performed in yeast suggest that the mismatch-repair machinery is not only involved in the repair of heteroduplexes formed during meiosis, but is also responsible for ensuring homologous recombination.

In light of this new evidence, we present a complete model of gene conversion that includes identity requirements and mismatch-repair. Results from our simulations suggest that the length of gene conversion tracts are a consequence of the action of these mechanisms and are consistent with the synthesis-dependent strand annealing model for gene conversion.