Solution Structure and Binding Properties of lcFABP in the Light Organ of Taiwanese Firefly, Luciola cerata

• Main Authors: Tseng, Kai Li, 曾凱莉
• Other Authors: Lyu, Ping Chiang
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/93705283273042934383

博士 === 國立清華大學 === 生物資訊與結構生物研究所 === 104 === Fatty acid-binding proteins (FABPs), members of the intracellular lipid-binding protein superfamily, are present in both vertebrates and invertebrates and constitute a considerable portion of many energy-consuming cells. FABPs mediate the solubilization and transport of fatty acids in the aqueous environment of the cytosol. FABPs from different invertebrate species have been identified in various tissue types, and many of them have suggested involvement in diverse physiological roles. A novel FABP, lcFABP, was previously characterized in the light organ of Taiwanese firefly Luciola cerata. lcFABP was suggested to supply energy for sustaining bioluminescent flashes by binding and transporting fatty acids; however, the precise molecular mechanisms underlying this process remain elusive as structural information on lcFABP is limited. In this study, the three-dimensional structure of lcFABP was determined by using the solution-state NMR spectroscopy. lcFABP adopts an overall β-clam conformation with ten anti-parallel β-strands and two short α-helices, which agrees with the general structural features of the FABP family. The 10 lowest-energy structures ensemble of lcFABP is of agreeable stereochemical quality and has been deposited to the Protein Data Bank (ID: 2N93). Inspection of the solution structure revealed that lcFABP adopts a unique extended βE-turn-βF stretches which is distinct from other FABPs. On the other hand, comparison of the ligand binding properties between wild-type lcFABP and a mutant, R125A, showed that R125 is crucial in determining ligand binding affinity. The lcFABP-fatty acid docking models have revealed possible interaction scheme between lcFABP and the ligand. These results disclose specific structural characteristics of lcFABP and imply the possible mechanisms underlying lcFABP-mediated ligand binding.