Structural basis of non-specific lipid binding in maize lipid-transfer protein complexes revealed by high-resolution X-ray crystallography

Non-specific lipid-transfer proteins (nsLTPs) are involved in the movement of phospholipids, glycolipids, fatty acids, and steroids between membranes. Several structures of plant nsLTPs have been determined both by X-ray crystallography and nuclear magnetic resonance. However, the detailed structura...

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Bibliographic Details
Published in:Journal of molecular biology 2001-04, Vol.308 (2), p.263-278
Main Authors: Han, G W, Lee, J Y, Song, H K, Chang, C, Min, K, Moon, J, Shin, D H, Kopka, M L, Sawaya, M R, Yuan, H S, Kim, T D, Choe, J, Lim, D, Moon, H J, Suh, S W
Format: Article
Language:English
Subjects:
Binding Sites
Carrier Proteins - chemistry
Carrier Proteins - metabolism
Crystallography, X-Ray
Decanoic Acids - metabolism
Fatty Acids - chemistry
Fatty Acids - metabolism
Humans
Hydrogen Bonding
Ligands
Models, Molecular
Oleic Acid - metabolism
Plant Proteins
Pliability
Protein Conformation
Serum Albumin - chemistry
Serum Albumin - metabolism
Substrate Specificity
Zea mays - chemistry
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Summary:Non-specific lipid-transfer proteins (nsLTPs) are involved in the movement of phospholipids, glycolipids, fatty acids, and steroids between membranes. Several structures of plant nsLTPs have been determined both by X-ray crystallography and nuclear magnetic resonance. However, the detailed structural basis of the non-specific binding of hydrophobic ligands by nsLTPs is still poorly understood. In order to gain a better understanding of the structural basis of the non-specific binding of hydrophobic ligands by nsLTPs and to investigate the plasticity of the fatty acid binding cavity in nsLTPs, seven high-resolution (between 1.3 A and 1.9 A) crystal structures have been determined. These depict the nsLTP from maize seedlings in complex with an array of fatty acids.A detailed comparison of the structures of maize nsLTP in complex with various ligands reveals a new binding mode in an nsLTP-oleate complex which has not been seen before. Furthermore, in the caprate complex, the ligand binds to the protein cavity in two orientations with equal occupancy. The volume of the hydrophobic cavity in the nsLTP from maize shows some variation depending on the size of the bound ligands. The structural plasticity of the ligand binding cavity and the predominant involvement of non-specific van der Waals interactions with the hydrophobic tail of the ligands provide a structural explanation for the non-specificity of maize nsLTP. The hydrophobic cavity accommodates various ligands from C10 to C18. The C18:1 ricinoleate with its hydroxyl group hydrogen bonding to Ala68 possibly mimics cutin monomer binding which is of biological importance. Some of the myristate binding sites in human serum albumin resemble the maize nsLTP, implying the importance of a helical bundle in accommodating the non-specific binding of fatty acids.
ISSN:0022-2836
1089-8638
DOI:10.1006/jmbi.2001.4559