We surveyed genetic interactions of the benign Snp1 C-terminal truncations with mud2∆, nam8∆, and mud1∆. The results (Figure 1B) disclosed an informative hierarchy of synthetic mutational effects. SNP1-(1-223), SNP1-(1-208), and SNP1-(1-193) were lethal at all temperatures in the absence of Mud2, indicating that the essential contributions of the Snp1 segment downstream of the RRM module to early spliceosome assembly/stability are buffered by the cross-intron bridging interactions of Mud2 (engaged with Msl5 at the branchpoint) with U1 snRNP at the 5′ splice site.