Figure 2.

J-domain structure determines partnership with Ssq1 and Ssc1. (A) Stimulation of the ATPase activity of Ssc1 and Ssq1 from Saccharomyces cerevisiae by chimaeral Jac1_ScY23 and Jac1_ScY23Δ13 proteins in the presence of Isu1_Sc. Data from Fig 1A of stimulation by Jac1_Sc and Jac1_Yl is included for comparison. The curves represent the best fit of the data to a Michaelis–Menten hyperbolic equation (supplementary Table S1 online). (B) Amino-acid sequence and structural model of Jac1_ScY23 and Jac1_ScY23Δ13. Green and blue represent sequences derived from Yarrowia lipolytica and S. cerevisiae, respectively. (C) Overexpression of Jac1_ScY23 suppresses the growth defect of Δjac1 Δssq1. Top panels: 10-fold serial dilutions (starting with approximately 10⁴ cells) of Δjac1 Δssq1 cells expressing plasmid-borne wild-type Jac1_Sc (wt) or Jac1_ScY23 (Y23) were plated on a rich glucose medium and incubated at 30°C for 3 days. Bottom panel: cell lysate from the indicated strains separated by electrophoresis and subjected to immunoblot analysis using antibodies specific for Jac1_Sc and, as a loading control, porin. Predicted molecular weight: Jac1_Sc, 21.6 kDa; Jac1_ScY23, 23.3 kDa. Sc, Saccharomyces cerevisiae; Yl, Yarrowia lipolytica.