Effect of phospholipids on conformational structure of bovine pancreatic trypsin inhibitor (BPTI) and its thermolabile mutants

Authors

  • Naoshige Izumikawa,

    1. School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
    Current affiliation:
    1. Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Nakamachi, Koganei-shi, Tokyo 184-8588, Japan
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  • Shingo Nishikori,

    1. Division of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 862-0976, Japan
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  • Mun'delanji Vestergaard,

    1. School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
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  • Tsutomu Hamada,

    1. School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
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  • Yoshihisa Hagihara,

    1. Research Institute for Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
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  • Noboru Yumoto,

    1. Research Institute for Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
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  • Kentaro Shiraki,

    1. Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
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  • Masahiro Takagi

    Corresponding author
    1. School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
    • School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
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Abstract

The effects of negatively charged phosphatidylserine-prepared membranes (PS) and neutral phosphatidylcholine-prepared membranes (PC) on the structure of wild-type and mutant bovine pancreatic trypsin inhibitor (BPTI) at neutral pH were investigated. The presence of PC did not have any effect on the protein structure while PS induced a non-native structure in three mutant BPTI proteins. However, the negatively charged membrane did not have any effect on wild-type BPTI. The findings revealed that (i) elimination of some disulphide bonds results in dramatic change in protein structure, and, (ii) that this biochemical interaction is surface-driven and electrostatic interactions may play a very strong role in influencing the fore-stated changes in protein structure. Of further interest were the results obtained from investigating the possible role of PS fluidity and concentration in altering mutant. When the value of Gibbs free-energy change of unfolding (ΔGU) was positive, various non-native structures were formed in a concentration-dependent manner. However, when the value of ΔGU was negative, only two types of non-native structures were formed: one with high β structure content at low PS fluidity state, and the other with a high α-helical content at high PS fluidity state. Our study reveals how particular combinations of phospholipid:protein interactions can induce a protein conformation transition from a native to a non-native one at neutral pH, especially when the native structure is predestabilized by amino acid substitutions. This revelation may open up opportunities to explore alternative ways in which phospholipids may play a role in protein mis-folding and the related pathologies. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 873–880, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to preprint version. You can request a copy of the preprint emailing the Biopolymers editorial office at biopolymers@wiley.com

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