The histone variant H2A.Z promotes initiation of meiotic recombination (expression)

Meiotic homologous recombination is a critical DNA-templated event for sexually-reproducing organisms. It is initiated by a programmed formation of DNA double strand breaks (DSBs), mainly formed at recombination hotspots, and is, like all other DNA-related processes, under great influence of chromatin structure. For example, local chromatin around hotspots directly impacts DSB formation. In addition, DSB is proposed to occur in a higher-order chromatin architecture termed axis-loop, in which many loops protrude from proteinaceous axis. Despite many recent insightful studies, still much remains unknown about how meiotic DSBs are generated in chromatin structure. Here, we show that the highly conserved histone H2A variant H2A.Z promotes meiotic DSB formation in fission yeast. Subsequent investigation revealed that H2A.Z is neither enriched around hotspots nor axis sites, and that transcript levels of DSB-promoting factors were maintained in the absence of H2A.Z. Instead, we found that H2A.Z facilitates chromatin binding of various proteins required for DSB formation. Strikingly, artificial tethering of one of such proteins, Rec10, to chromatin partially restored DSB reduction in H2A.Z-lacking cells. Based on these, we conclude that fission yeast H2A.Z promotes initiation of meiotic recombination partly through delivering DSB-related proteins onto chromatin.

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Yamada S, Kugou K, Ding DQ, Fujita Y, Hiraoka Y, Murakami H, Ohta K, Yamada T