Genetic interactions of hypomorphic mutations in the m⁷G cap-binding pocket of yeast nuclear cap binding complex: An essential role for Cbc2 in meiosis via splicing of MER3 pre-mRNA

cbc2-Y24A is synthetic lethal with mud2Δ and nam8Δ and synthetic sick with mud1Δ, swt21Δ, brr1Δ, and ist3Δ. (A) Yeast cbc2-Y24A mud2Δ p360-MUD2 (URA3 CEN MUD2) or cbc2-Y24A nam8Δ p360-NAM8 (URA3 CEN NAM8) cells were transformed with CEN LEU2 plasmids harboring wild-type CBC2, MUD2, or NAM8 as specified. Leu⁺ transformants were selected at 30°C and then streaked to agar medium containing 5-FOA (0.75 mg/mL). Cells transformed with the empty LEU2 vector served as a negative control. The plates were photographed after 3 d of incubation at 30°C or 37°C. (B) Aliquots (3 μL) of serial 10-fold dilutions of haploid yeast strains of the specified genotypes were spotted on YPD agar medium. The plates were photographed after incubation for 2 d (30°C, 34°C, and 37°C), 3 d (25°C), or 5 d (20°C) as specified.