Fig. 7. Suboptimal TAs are bound to Sgt2 less stably, which correlates with reduced Sgt2 closing.

a, b 4AG, 5AG and 6AG were efficiently loaded onto Sgt2 by Ssa1 (a), whereas Fis1 was not (b). TA transfer was measured using UV-induced crosslink of TA^Bpa, as described in Methods. The percentage of crosslinked Sgt2-TA is indicated underneath and represented as mean ± SD, with n = 3. c, d Suboptimal TAs dissociate more quickly from Sgt2. Time courses of the dissociation of Bos1, 4AG, and 6AG were measured as in Fig. 1c using cpSRP43 as chase (c). Data are normalized such that F = 0 at t = 0, and F = 1 at the end of the reaction. The data for Bos1 were fit to a single exponential function (Eq. 1), and the data for 4AG and 6AG were fit to double exponential functions with a fast and slow phase (Eq. 2). The obtained rate constants are summarized in d as mean ± SD, with n = 3. e smFRET histogram of Ssa1-Sgt2-TA for the indicated TA variants. The histogram for Sgt2 in the presence of Ssa1 and Ydj1 without TA (hot pink) is shown for comparison. f Summary of the equilibrium of Sgt2 closing obtained from mpH²MM analysis. Source data are provided in the Source Data file.