Figure 5.

Genetic analysis identified genes functionally linked to the U1 snRNA 5′-end dinucleotide. Nine candidate genes (except for BBP allele msl5-S194P) marked on the right emerged first from an SGA screen using the UU mutation, among them six are related to splicing (light brown) and three to transcription (light purple). Genetic interaction of these nine candidate genes and msl5-S194P with all the U1 snRNA mutants was further manually analyzed in a pairwise manner. The severities of synthetic lethality, ranging from viable to lethal, are presented in a heat map (top half). Temperature-dependent synthetic lethality between tgs1Δ and all the U1 snRNA mutations is presented in the bottom half. See text for detailed discussion of the biological underpinning of Groups I, II and III.