Research on the GST gene family in Salix lindleyana reveals Trp162 and Pro202 as key amino acids controlling the release rate of GS-X

The adaptive evolution of the glutathione S-transferase (GST) gene family in Salix lindleyana provides insights into the relationship between enzyme structure and function. In this study, 37 genes encoding the GST protein were cloned from S. lindleyana with no genomic data available, and their expression levels and enzyme activity were determined in vitro. The 22 genes encoding the Tau GST subfamily were divided into Clades A and B, with Clade A subjected to more relaxed selection pressure than Clade B. Clade A was split into two smaller branches, Clades a and b. Three genes under positive selection from Clade a were chosen for 36 site-directed mutations, with Trp162 and Pro202 crucially affecting variations in GST enzyme activity. Crystal structure analysis of SliGSTU7 complexed with GSH revealed that the Trp162 residue was located at the bottom of the hydrophobic cavity. Homology modeling and molecular docking revealed that the W162G/P202A mutation in SliGSTU7 significantly reduced the neighboring effect during the formation of GS-DNB. A study of the GST gene family of S. lindleyana identified Trp162 and Pro202 as key amino acids that regulate the release rate of GS-X.