title: Structural Insights on PHA Binding Protein PhaP from Aeromonas hydrophila.
abstract: Phasins or PhaPs are a group of amphiphilic proteins that are found attached to the surface of microbial polyhydroxyalkanoate (PHA) granules. They have both structural and regulatory functions and can affect intracellular PHA accumulation and mediate protein folding. The molecular basis for the diverse functions of the PhaPs has not been fully understood due to the lack of the structural knowledge. Here we report the structural and biochemical studies of the PhaP cloned from Aeromonas hydrophila (PhaPAh), which is utilized in protein and tissue engineering. The crystal structure of PhaPAhwas revealed to be a tetramer with 8 α-helices adopting a coiled-coil structure. Each monomer has a hydrophobic and a hydrophilic surface, rendering the surfactant properties of the PhaPAhmonomer. Based on the crystal structure, we predicted three key amino acid residues and obtained mutants with enhanced stability and improved emulsification properties. The first PhaP crystal structure, as reported in this study, is an important step towards a mechanistic understanding of how PHA is formed in vivo and why PhaP has such unique surfactant properties. At the same time, it will facilitate the study of other PhaP members that may have significant biotechnological potential as bio-surfactants and amphipathic coatings.
authors.affiliation: Center for Synthetic and Systems Biology, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wei
authors.affiliation: MOE Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: Center for Synthetic and Systems Biology, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Yao
authors.affiliation: MOE Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Manyu
authors.initials: M
authors.lastname: Xu
authors.affiliation: Center for Synthetic and Systems Biology, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Daixu
authors.initials: D
authors.lastname: Wei
authors.affiliation: MOE Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Wang
authors.affiliation: MOE Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, Beijing 100084, China.|Collaborative Innovation Center for Biotherapy, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, China.
authors.forename: Xinquan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Center for Synthetic and Systems Biology, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.|Center for Nano and Micro-Mechanics, Tsinghua University, Beijing 100084, China.|MOE Key Lab for Industrial Biocatalysis, Tsinghua University, Beijing 100084, China.
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D016980:Aeromonas hydrophila / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D000072756:Protein Conformation, alpha-Helical; D017510:Protein Folding
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C118828:PHAP protein, Bacteria