The conformation of yeast chromosome III is mating type dependent and controlled by the recombination enhancer

Belton, Jon-Matthew; Lajoie, Bryan R.; Audibert, Sylvain; Cantaloube, Sylvain; Lassadi, Imen; Goiffon, Isabelle; Baù, Davide; Marti-Renom, Marc A.; Bystricky, Kerstin; Dekker, Job

doi:http://dx.doi.org/10.1016/j.celrep.2015.10.063

The conformation of yeast chromosome III is mating type dependent and controlled by the recombination enhancer

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Belton JM, Lajoie BR, Audibert S, Cantaloube S, Lassadi I, Goiffon I, et al. The conformation of yeast chromosome III is mating type dependent and controlled by the recombination enhancer. Cell Reports. 2015 Dec 01;13(9):1855-67. DOI: 10.1016/j.celrep.2015.10.063

Abstract

Mating-type switching in yeast occurs through gene conversion between the MAT locus and one of two silent loci (HML or HMR) on opposite ends of the chromosome. MATa cells choose HML as template, whereas MATα cells use HMR. The recombination enhancer (RE) located on the left arm regulates this process. One long-standing hypothesis is that switching is guided by mating-type-specific and possibly RE-dependent chromosome folding. Here, we use Hi-C, 5C, and live-cell imaging to characterize the conformation of chromosome III in both mating types. We discovered a mating-type-specific conformational difference in the left arm. Deletion of a 1-kb subregion within the RE, which is not necessary during switching, abolished mating-type-dependent chromosome folding. The RE is therefore a composite element with one subregion essential for donor selection during switching and a separate region involved in modulating chromosome conformation.