Page 4 - S. Plant biology

[S. Plant biology-2]

Chaperone function of Arabidopsis NPR1

Su Bin Bae¹˙#, Ho Byoung Chae¹, Seol Ki Paeng¹, Yong Hun Chi¹, Seong Dong Wi¹, Kieu Anh Thi Phan¹,
Sang Yeol Lee¹˙*

¹Division of Applied Life Sciences (BK21+) and PMBBRC, Gyeongsang National University, Jinju 52828, Korea

Among the defense systems, the NPR1 playing a key role in a plant systemic acquired immune responses has been

shown to have multiple functions. The molecular structure of NPR1 has two domains, BTB/POZ and ANK repeat,
that are involved in protein–protein interactions. Despite the function of its SA-induced defense activity in nucleus,

the biochemical property of its cytosolic oligomers has not been elucidated. Based on the results that the reversible
structural change of redox proteins is a typical property of molecular chaperones, we investigated the biochemical

characteristics of NPR1. From the study, the recombinant NPR1 functions as a protein chaperone to protect plants
from heat stress through its structural switching by its oligomer form. Under heat-induced condition, the NPR1

protein prevents from aggregation of substrate. And the structural change was regulated upon the redox changes,
such as DTT treatment dissociated its structure to monomer and reduced its chaperone activity, suggesting that the

heat-induced chaperone activity of NPR1 is dependent on its redox status. In summary, the cytosolic NPR1 oligomer
performs the important function of molecular chaperone to protect plants from heat stress that can be applied to

the preparation of heat shock-tolerant useful crops.