Fig. 3.

The resulting point mutations of Spt15 and localization. a Schematic diagram of interactions among Spt15, DNA and other components in the RNA Pol II general transcription machinery. b The resulting 36 Spt15 mutations with altered stress tolerance capacities are mapped on the Spt15 secondary structure. The evaluation results of stress tolerance capacities were extracted from Figs. 4, 5 and Additional file 1: Fig. S1. Common stress-tolerant and sensitive mutations at all three stress conditions (hyperosmotic, thermal and ethanol) are highlighted in red and in green, respectively. Mutations with specific stress-tolerant and opposite stress-resistant capacities at different stress conditions are highlighted in pink and in blue, respectively. P20R and T38S were tolerant to hyperosmotic and thermal stresses, but sensitive to ethanol stress. V71L was tolerant to ethanol stress, but sensitive to hyperosmotic and thermal stresses. P65L was only tolerant to ethanol stress, but showed similar fermentation capacities to the wild-type strain at other conditions. Names of elements of secondary structure follow the convention reported previously [38, 59]. H, represents α-helix. S, represents β-sheet. Mutations localized at the concave surface of the tertiary structure of Spt15 were boxed. c Location of the resulting Spt15 mutations on its tertiary structure (PDB 1YTB)