Figure S1.

Mrc1 maintains heterochromatin independently of its functions in genome stability and origin regulation, related to Figure 2

(A) H3K9me2 levels in mrc1ΔHBS mutants with an (EcoRV)::ura4⁺ reporter. (EcoRV)::ura4⁺ and (EcoRV)::mCherry differ only at their ORF. (EcoRV)::ura4⁺ was used to select for cells in the expressed state by propagating them in EMM2 medium lacking uracil. Statistics using unpaired Student’s t test. Average of three independent replicates. H3K9me2 was analyzed by ChIP-seq. The bar-diagram shows H3K9me2 levels quantified by ChIP-seq normalized to input and shown relative to signal at cnt3.

(B and C) Histograms of mCherry cell fluorescence intensities used to generate Figure 2B B and Figure 2C C.

(D) Histograms of mCherry cell fluorescence intensities used to generate Figure 2G and representative micrographs. Note that some hsk1-89 cells displayed autofluorescence rather than the expected nuclear signal for YFP expression. Scale bar: 10 μm.

(E) Mrc1 functions redundantly with the REII element to repress mat2-P mating-type information, dependent on the HBS domain. The proportion of cells undergoing haploid meiosis is shown as in Figure 2H but for the REII⁺ control. Scale bar: 1 μm.

(F) Mrc1 and HBS domain are necessary for the repression of the (XbaI)::ura4⁺ reporter gene near mat2-P, redundantly with the REII element. Ten-fold serial dilutions of cell suspensions were spotted onto the indicated media. Growth on AA-ura reflects ura4⁺ expression while growth on the toxigenic substrate FOA reflects ura4⁺ repression.