Solution Nuclear Magnetic Resonance Studies of Sterol Carrier Protein 2 Like 2 (SCP2L2) Reveal the Insecticide Specific Structural Characteristics of SCP2 Proteins in Aedes aegypti Mosquitoes

Abstract

Sterol carrier protein 2 like 2 from Aedes aegypti (AeSCP2L2) plays an important role in lipid transport in mosquitoes for its routine metabolic processes. Repeated unsuccessful attempts to crystallize ligand free SCP2L2 prompted us to undertake nuclear magnetic resonance (NMR) spectroscopy to determine its three-dimensional structure. We report here the three-dimensional structures and dynamics of apo-AeSCP2L2 and its complex with palmitate. The (15)N heteronuclear single-quantum coherence spectrum of apo-AeSCP2L2 displayed multiple peaks for some of the amide resonances, implying the presence of multiple conformations in solution, which are transformed to a single conformation upon formation of the complex with plamitate. The three-dimensional structures of apo-AeSCP2L2 and palmitated AeSCP2L2 reveal an α/β mixed fold, with five β-strands and four α-helices, very similar to the other SCP2 protein structures. Unlike the crystal structure of palmitated AeSCP2L2, both solution structures are monomeric. It is further confirmed by the rotational correlation times determined by NMR relaxation times (T1 and T2) of the amide protons. In addition, the palmitated AeSCP2L2 structure contains two palmitate ligands, bound in the binding pocket, unlike the three palmitates bound in the dimeric form of AeSCP2L2 in the crystals. The relaxation experiments revealed that complex formation significantly reduces the dynamics of the protein in solution.

Biological evaluation of a series of benzothiazole derivatives as mosquitocidal agents

“…aegypti SCP-2 (AeSCP2), has been reported to be involved in cholesterol and fatty acid uptake in the midgut in both larval and adult mosquitoes [16]. A small number of studies have focused on developing new insecticides that prevent cholesterol biosynthesis targeting AeSCP2 [17][18][19]. Fifty seven compounds were identified in silico as possible inhibitors of the cholesterol-binding capacity of SCP-2 from the library of 16000 compounds [20].…”

Enhanced Larvicidal Activity of New 1,2,4-Oxadiazoles against Aedes aegypti Mosquitos: QSAR and Docking Studies

“…It highlights that a theoretically oriented chemical modification (in this case the introduction of the second phenyl ring) represents a rational design strategy for exploring opportunities of intermolecular hydrophobic interaction offered by the biomolecular target AeSCP-2. In this sense, it is interesting to observe that, recently, Singarapu et al 45 using solution NMR experiments showed that Sterol Carrier Protein 2 Like 2 (SCP2L2) can interact to palmitate through the hydrophobic residues Ile, Val, Leu, Met and Ala. Therefore, these results shed lights on the possibility that 1,2,4-oxadiazol acid derivatives presented in this work may also interact to this isoform of AeSCP2.…”

Binding properties of sterol carrier protein 2 (SCP2) characterized using Laurdan

“…Simple equilibrium calculations demonstrate that partial displacement is difficult to explain by a single-site binding competition model; whereas partial displacement is accounted for by the more complex binding model proposed here. Second, the three-dimensional structure of the binding site, ligand location and orientation, and binding stoichiometry exhibit remarkable variability in the SCP2 family, as if it had evolved not only to cage most lipids but to carry more than one [2,9].…”

“…Among the cellular functions of SCP2 are: nonvesicular lipid transport and storage; membrane remodeling, lipid mediated signaling, isoprenoid and cholesterol metabolism, steroidogenesis, peroxisomal oxidation of branched and long-chain fatty acids, and cholesterol uptake [3][4][5][6][7][8][9]. Most of what is known about SCP2 concerns eukaryotic cells, whereas the functions of SCP2 in prokaryota are unexplored.…”