GmSK2-8 Kinase Inhibits GmNSP1a DNA-Binding Activity via Phosphorylation

GmSK2-8 kinase was found to inhibit the DNA-binding activity of GmNSP1a through phosphorylation. Utilizing a biotin-labeled DNA fragment encompassing nucleotides -336 to -1 of the GmERN1a promoter, which contains four AATTT elements (Figure 5B), we observed a reduction in the binding of GmNSP1a to the GmERN1a promoter (Figure 5C) upon the addition of GmSK2-8 kinase and ATP (Figure 5D). These findings suggest that GmSK2-8 negatively regulates GmNSP1a's interaction with the GmERN1a promoter by phosphorylating GmNSP1a, thereby impacting its DNA-binding capabilities.