Download MendeleyCrystal structure of Epiphyas postvittana takeout 1 with bound ubiquinone supports a role as ligand carriers for takeout proteins in insects
Hamiaux, C., Stanley, D., Greenwood, D.R., Baker, E.N., Newcomb, R.D.(2009) J Biol Chem 284: 3496-3503
- PubMed: 19073605
- DOI: https://doi.org/10.1074/jbc.M807467200
- Primary Citation of Related Structures:
3E8T, 3E8W - PubMed Abstract:
Takeout (To) proteins are found exclusively in insects and have been proposed to have important roles in various aspects of their physiology and behavior. Limited sequence similarity with juvenile hormone-binding proteins (JHBPs), which specifically bind and transport juvenile hormones in Lepidoptera, suggested a role for To proteins in binding hydrophobic ligands. We present the first crystal structure of a To protein, EpTo1 from the light brown apple moth Epiphyas postvittana, solved in-house by the single-wavelength anomalous diffraction technique using sulfur anomalous dispersion, and refined to 1.3 angstroms resolution. EpTo1 adopts the unusual alpha/beta-wrap fold, seen only for JHBP and several mammalian lipid carrier proteins, a scaffold tailored for the binding and/or transport of hydrophobic ligands. EpTo1 has a 45 angstroms long, purely hydrophobic, internal tunnel that extends for the full length of the protein and accommodates a bound ligand. The latter was shown by mass spectrometry to be ubiquinone-8 and is probably derived from Escherichia coli. The structure provides the first direct experimental evidence that To proteins are ligand carriers; gives insights into the nature of endogenous ligand(s) of EpTo1; shows, by comparison with JHBP, a basis for different ligand specificities; and suggests a mechanism for the binding/release of ligands.
Organizational Affiliation:
The Horticulture and Food Research Institute of New Zealand Limited (HortResearch), Private Bag 92169, Auckland 1142, New Zealand.
