title: Chaperone-like effect of the linker on the isolated C-terminal domain of rabbit muscle creatine kinase.
abstract: Intramolecular chaperones (IMCs), which are specific domains/segments encoded in the primary structure of proteins, exhibit chaperone-like activity against the aggregation of the other domains in the same molecule. In this research, we found that the truncation of the linker greatly promoted the thermal aggregation of the isolated C-terminal domain (CTD) of rabbit muscle creatine kinase (RMCK). Either the existence of the linker covalently linked to CTD or the supply of the synthetic linker peptide additionally could successfully protect the CTD of RMCK against aggregation in a concentration-dependent manner. Truncated fragments of the linker also behaved as a chaperone-like effect with lower efficiency, revealing the importance of its C-terminal half in the IMC function of the linker. The aggregation sites in the CTD of RMCK were identified by molecular dynamics simulations. Mutational analysis of the three key hydrophobic residues resulted in opposing effects on the thermal aggregation between the CTD with intact or partial linker, confirming the role of linker as a lid to protect the hydrophobic residues against exposure to solvent. These observations suggested that the linkers in multidomain proteins could act as IMCs to facilitate the correct folding of the aggregation-prone domains. Furthermore, the intactness of the IMC linker after proteolysis modulates the production of off-pathway aggregates, which may be important to the onset of some diseases caused by the toxic effects of aggregated proteolytic fragments.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China; Key Laboratory of Bio-Resources and Eco-Environment of MOE, College of Life Science, Sichuan University, Chengdu, China.
authors.forename: Xiang-Jun
authors.initials: XJ
authors.lastname: Chen
authors.affiliation: MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Mengdie
authors.initials: M
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China.
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: He
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Wang
authors.affiliation: MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Liu
authors.affiliation: MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Haipeng
authors.initials: H
authors.lastname: Gong
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China. Electronic address: ybyan@tsinghua.edu.cn.
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Yan
mesh_terms: D000818:Animals; D052283:Creatine Kinase, MM Form / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009154:Mutation; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D011817:Rabbits; D013696:Temperature
chemical_list: D052283:Creatine Kinase, MM Form