Fig 5. Adaptive genetic changes improve sister chromosome cohesion in Rec8-expressing cells.

(A) Individual adaptive genetic changes partially improve sister chromosome cohesion. Deletions of genes in the Cdk8 complex, adaptive mutations in cohesin and its regulator, two copies of SCC3, and deletion of genes that regulate G1-to-S transition were reconstructed individually in the strain used for assaying sister chromosome cohesion. Cells were prepared as in Fig 1C, and the percentage of cells with two GFP dots in populations arrested in mitosis (150 minutes after releasing from G1) is shown. The darker gray points represent the values of three biological replicates, and the thinner gray bar represents one standard deviation on each side of the mean of these measurements. The statistical significance between data from the Rec8-expressing strain and each mutation-reconstructed strain was calculated by two-tailed Student t test, *p < 0.05, **p < 0.01. (B-F) Relative fitness and sister chromosome cohesion of double mutants are shown: ssn2Δ and smc1-P15 (B), mbp1Δ and smc1-P15 (C), ssn2Δ and mbp1Δ (D), ssn2Δ and esp1-P15 (E), mbp1Δ and esp1-P15 (F). The blue dashed line represents the expected fitness if two mutations contribute additively, and the shaded region represents the standard error of that expectation. Data associated with Fig 5A–5F can be found in S1 Data. Cdk8, cyclin dependent kinase 8; GFP, green fluorescent protein; Rec8, recombination 8; SCC3, sister chromosome cohesion 3.