Genetic interactions among LSG1, NMD3 and RPL10. (A) lsg1 and nmd3 mutants exhibit synthetic lethality. AJY1513 (nmd3–3), AJY1518 (nmd3–4), AJY1511 (lsg1∷KanMX4/pAJ626[LSG1 URA3]), AJY1512 (lsg1∷KanMX4nmd3–3/pAJ626[LSG1 URA3]), AJY1521 (lsg1∷KanMX4nmd3–4/pAJ626[LSG1 URA3]) and a congenic wild-type strain were transformed with lsg1-2 and lsg1-3 mutant alleles on LEU2 plasmids. Transformants were restreaked onto 5-FOA plates to exclude the wild-type LSG1∷URA3 plasmids. Plates were incubated at 25°C for 10 days. (B) Growth suppression of a dominant-negative LSG1 allele by high-copy NMD3. In all, 10-fold serial dilutions of stationary-phase cultures were spotted onto selective plates containing galactose and incubated for 5 days at 30°C. The strains tested were: wild-type (CH1305) transformed with pAJ1109 (GAL10∷LSG1[K349T]) in combination with empty vector (pRS416), pAJ409 (NMD3, CEN), pAJ363 (NMD3, 2μ) or pAJ1143 (GAL1∷NMD3,CEN). The growth of wild-type (CH1305), containing empty vectors, and LSG1(K349T), suppressed with high-copy NMD3, is shown for comparison. (C) Growth suppression of dominant-negative LSG1 and rpl10ts mutants by NMD3 suppressor alleles. Cultures of either CH1305 containing pAJ1278 (GAL10∷LSG1[K349T]) or AJY1657 (rpl10[G161D]), each also containing empty vector (pRS415), pAJ538 (NMD3-myc), pAJ415 (NMD3[L291F]-myc) or pAJ1315 (NMD3[I112T, I362T]-myc), were diluted and plated as for (B). The CH1305 plate was incubated 5 days at 30°C and the AJY1657 plate for 3 days at 35°C.