Interactions between various classes of U6 and prp8 N-terminal alleles. (A) The model of rearrangements of the catalytic center between the two catalytic steps. Four classes of alleles are marked by colored boxes: those promoting exit from the first-step catalytic conformation and entry into the transition-state conformation (light red); those promoting entry into the transition-state conformation through destabilization of both catalytic steps (red); those inhibiting exit from the first-step catalytic conformation (light blue), and those promoting both catalytic conformations (blue). (B) Genetic interactions between prp8-T589P, Y590F, K603I, K611T, S613T and U6-A59c, C61a, A79g, G63c, A42g, C43u alleles in prp8Δ U6Δ strain (yCQ05) tested by growth in the presence of 5FOA. prp8-T589P, K603I, K611T, S613T alleles become synthetically lethal in combination with U6-A59c. U6-C61a and A79g become synthetically lethal with prp8-K611T allele or cs and/or ts in combination with prp8-T589P, Y590F, K603I, S613T alleles. prp8-T589P, Y590F, K603I, K611T alleles do not affect growth in combination with U6-G63c, A42g, C43u, compared to wt U6.
