Involvement of the residues of GSKIP, AxinGID, and FRATtide in their binding with GSK3[beta] to unravel a novel C-terminal scaffold-binding region

Mol Cell Biochem (2010) 339:2333 DOI 10.1007/s11010-009-0366-0

Involvement of the residues of GSKIP, AxinGID, and FRATtide in their binding with GSK3b to unravel a novel C-terminal scaffold-binding region

Shen-Long Howng Chi-Ching Hwang Chia-Yi Hsu Meng-Yu Hsu

Chun-Yen Teng Chia-Hua Chou Mei-Feng Lee Chia-Hung Wu

Shean-Jaw Chiou Ann-Shung Lieu Joon-Khim Loh Chia-Ning Yang

Chan-Shing Lin Yi-Ren Hong

Received: 25 September 2009 / Accepted: 16 December 2009 / Published online: 31 December 2009 Springer Science+Business Media, LLC. 2009

Abstract The specicity and regulation of GSK3b are thought to involve in the docking interactions at core kinase domain because of the particular amino acid residues. Recent X-ray diffraction studies illuminated the relative binding residues on AxinGID and FRATtide for GSK3b docking and appeared that GSK3b Val267Gly (V267G) and Tyr288Phe (Y288F) could distinguish the direct interaction between AxinGID and FRATtide. In order to explore the mode that involved the binding of GSKIP to GSK3b and compare it with that of AxinGID and FRATtide, we pinpointed the binding sites of GSKIP to GSK3b through the

single-point mutation of four corresponding sites within GSK3b (residues 260300) as scaffold-binding region

I (designated SBR-I260300). Our data showed that these

three binding proteins shared similar binding sites on GSK3b. We also found that the binding of GSK3b V267G mutant to GSKIP and AxinGID, but not that of Y288F mutant (effect on FRATtide), was affected. Further, based on the simulation data, the electron-density map of GSKIPtide bore closer similarity to the map AxinGID than to that of FRATtide. Interestingly, many C-terminal helix region point-mutants of GSK3b L359P, F362A, E366K, and

L367P were able to eliminate the binding with FRATtide, but not AxinGID or GSKIP. In addition, CABYR exhibited a unique mode in binding to C-terminal helix region of GSK3b. Taken together, our data revealed that in addition to the core kinase domain, SBR-I260300, another novel C-ter

minus helix region, designated SBR-II339383, also appeared

to participate in the recognition and specicity of GSK3b in binding to other specic proteins.

Keywords GSKIP AxinGID FRATtide GSK3b

GSK3b-binding protein Scaffold-binding region

Introduction

Functionally GSK3 acts as a downstream regulatory switch in glycogen metabolism as well as in numerous signaling pathways initiated by diverse stimuli [14]. Many human diseases, including diabetes, bipolar disorder, Alzheimers disease, and several cancers [39] have...