Figure 5.

SSB1 is an efficient high-copy suppressor of growth defects displayed by the glucose repression mutant Δreg1. Serial dilutions of logarithmically growing wild-type and mutant cells were analyzed on glucose-containing (YPD) or glycerol-containing (YPG) plates. Temperatures and incubation times are indicated. (A) Growth defects of the triple deletion strains Δssb1Δssb2Δreg1, Δssb1Δssb2Δsnf1, and of Δssb1Δssb2 overexpressing either REG1 or SNF1. (B) Complementation of Δreg1-related growth defects by high levels of SSB1 at 30°C and at 37°C. (C) Overexpression of different cytosolic chaperones in the Δreg1 strain. Expression of SSB1, SSA1, SSE1, SSZ1, and ZUO1 in the different strain backgrounds was from 2μ plasmids under the control of the respective endogenous promoter. Growth medium, temperatures, and incubation times are indicated. (D) Overexpression of mutant versions of SSB1 in Δreg1. Expression of SSB1, SSB1-K73A (ATPase-deficient mutant), and SSB1-ΔC (mutant lacking the peptide-binding domain) were overexpressed from 2μ plasmids under the control of the SSB1 promoter.