Page 2 - S. Plant biology

[S. Plant biology-1]

AtTPR10 containing multiple ANK and TPR domains exhibits

chaperone activity and heat-shock dependent structural

switching

Ho Byoung Chae¹˙#, Su Bin Bae¹, Seol Ki Paeng¹, Chang Ho Kang¹, Joung Hun Park¹, Eun Seon Lee¹,

Sang Yeol Lee¹˙*

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

Among the several tetratricopeptide (TPR) repeat-containing proteins encoded by the Arabidopsis thaliana genome,

AtTPR10 exhibits an atypical structure with three TPR domain repeats at the C-terminus in addition to seven ankyrin
(ANK) domain repeats at the N-terminus. However, the function of AtTPR10 remains elusive. Here, we investigated

the biochemical function of AtTPR10. Bioinformatic analysis revealed that AtTPR10 expression is highly enhanced
by heat shock compared with the other abiotic stresses, suggesting that AtTPR10 functions as a molecular chaperone

to protect intracellular proteins from thermal stresses. Under the heat shock treatment, the chaperone activity of
AtTPR10 increased significantly; this was accompanied by a structural switch from the low molecular weight (LMW)

protein to a high molecular weight (HMW) complex. Analysis of two truncated fragments of AtTPR10 containing
the TPR and ANK repeats showed that each domain exhibits a similar range of chaperone activity (approximately

one-third of that of the native protein), suggesting that each domain cooperatively regulates the chaperone function
of AtTPR10. Our results clearly demonstrate that AtTPR10 functions as a molecular chaperone in plants to protect

intracellular targets from heat shock stress.