The structural determination of an insect sterol carrier protein-2 with a ligand-bound C16 fatty acid at 1.35-A resolution.
Yellow fever mosquito sterol carrier protein (SCP-2) is known to bind to cholesterol. We report here the three-dimensional structure of the complex of SCP-2 from Aedes aegypti with a C16 fatty acid to 1.35-A resolution. The protein fold is exceedingly similar to the human and rabbit proteins, which consist of a five-stranded beta-sheet that exhibits strand order 3-2-1-4-5 with an accompanying layer of four alpha-helices that cover the beta-sheet. A large cavity exists at the interface of the layer alpha-helices and the beta-sheet, which serves as the fatty acid binding site. The carboxylate moiety of the fatty acid is coordinated by a short loop that connects the first alpha-helix to the first beta-strand, whereas the acyl chain extends deep into the interior of the protein. Interestingly, the orientation of the fatty acid is opposite to the observed orientation for Triton X-100 in the SCP-2-like domain from the peroxisomal multifunctional enzyme (Haapalainen, A. M., van Aalten, D. M., Merilainen, G., Jalonen, J. E., Pirila, P., Wierenga, R. K., Hiltunen, J. K., and Glumoff, T. (2001) J. Mol. Biol. 313, 1127-1138). The present study suggests that the binding pocket in the SCP-2 family of proteins may exhibit conformational flexibility to allow coordination of a variety of lipids.
Dyer
David H
DH
Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Lovell
Scott
S
Thoden
James B
JB
Holden
Hazel M
HM
Rayment
Ivan
I
Lan
Que
Q
D000101:Acetyl-CoA C-Acetyltransferase / Q000737:chemistry*; D000330:Aedes / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002264:Carboxylic Acids / Q000737:chemistry; D002352:Carrier Proteins / Q000737:chemistry*; D002784:Cholesterol / Q000378:metabolism; D018360:Crystallography, X-Ray; D003902:Detergents / Q000494:pharmacology; D004583:Electrons; D005227:Fatty Acids / Q000737:chemistry*; D008024:Ligands; D008055:Lipids / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017830:Octoxynol / Q000494:pharmacology; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D002264:Carboxylic Acids; D002352:Carrier Proteins; D003902:Detergents; D005227:Fatty Acids; D008024:Ligands; D008055:Lipids; D011994:Recombinant Proteins; C072087:sterol carrier proteins; D017830:Octoxynol; D002784:Cholesterol; D000101:Acetyl-CoA C-Acetyltransferase