title: NMR structure and function of Helicoverpa armigera sterol carrier protein-2, an important insecticidal target from the cotton bollworm.
abstract: The cotton bollworm, Helicoverpa armigera, has developed strong resistance to many insecticides. Sterol Carrier Protein-2 (SCP-2) is an important non-specific lipid transfer protein in insects and appears to be a potential new target. In order to elucidate the structure and function of Helicoverpa armigera SCP-2 (HaSCP-2), NMR spectroscopy, docking simulations, mutagenesis and bioassays were performed. HaSCP-2 composed of five α-helices and four stranded β-sheets. The folds of α-helices and β-sheets interacted together to form a hydrophobic cavity with putative entrance and exit openings, which served as a tunnel for accommodating and transporting of lipids. Several sterols and fatty acids could interact with HaSCP-2 via important hydrophobic sites, which could be potential targets for insecticides. Mutagenesis experiments indicated Y51, F53, F89, F110, I117 and Q131 may be the key functional sites. HaSCP-2 showed high cholesterol binding activity and SCP-2 inhibitors (SCPIs) could inhibit the biological activity of HaSCP-2. SCPI-treated larvae at young stage showed a significant decrease of cholesterol uptake in vivo. Our study describes for the first time a NMR structure of SCP-2 in lepidopteran H. armigera and reveals its important function in cholesterol uptake, which facilitates the screening of effective insecticides targeting the insect cholesterol metabolism.
authors.affiliation: School of Life Sciences, Central China Normal University, Wuhan, P.R.China.
authors.forename: Haihao
authors.initials: H
authors.lastname: Ma
authors.affiliation: School of Life Sciences, Central China Normal University, Wuhan, P.R.China.
authors.forename: Yuemin
authors.initials: Y
authors.lastname: Ma
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R.China.
authors.forename: Xuehui
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biochemistry and Entomology, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, United States of America.
authors.forename: David H
authors.initials: DH
authors.lastname: Dyer
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R.China.
authors.forename: Pingyong
authors.initials: P
authors.lastname: Xu
authors.affiliation: School of Life Sciences, Central China Normal University, Wuhan, P.R.China.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Biochemistry and Entomology, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, United States of America.
authors.forename: Que
authors.initials: Q
authors.lastname: Lan
authors.affiliation: School of Life Sciences, Wuhan Institute of Bioengineering, Wuhan, P.R.China.
authors.forename: Huazhu
authors.initials: H
authors.lastname: Hong
authors.affiliation: School of Life Sciences, Central China Normal University, Wuhan, P.R.China.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Peng
authors.affiliation: School of Life Sciences, Central China Normal University, Wuhan, P.R.China.
authors.forename: Rong
authors.initials: R
authors.lastname: Peng
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry; D015870:Gene Expression; D057927:Hydrophobic and Hydrophilic Interactions; D007306:Insecticides / Q000494:pharmacology; D008024:Ligands; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D002352:Carrier Proteins; D007306:Insecticides; D008024:Ligands; D011994:Recombinant Proteins; C072087:sterol carrier proteins; D002784:Cholesterol