Key residues for maintaining architecture, assembly of plant hormone SA receptor NPR1.

Salicylic acid (SA) is a pivotal hormone required for the development of resistance to many pathogens in plants. As an SA receptor, NPR1(Nonexpressor of Pathogenesis-Related Genes 1) plays a key regulatory role in the plant immune response. The function of NPR1 is dependent on the alteration of its oligomer-to-monomer. Research in recent years has proven that NPRs perceive SA and regulate the expression of downstream defense genes, but the mechanism of NPR1 oligomer-to-monomer conversion remains unclear. In this paper, we mainly studied the oligomerization of NPR1. By mutation experiments on some residues in the BTB domain involved in protein interactions, we found that the residue His80 plays a key role in the oligomerization of NPR1. We also found that NPR1, interacting with zinc ions at a ratio close to 1:1, was independent of the residue His80. These findings may help us to understand the conformational conversion of NPR1.