STRUCTURAL BASIS OF LIPID BINDING IN RICE NON-SPECIFIC LIPID TRANSFER PROTEIN COMPLEXES

Yuh-Ju Sun, Cheng Pei-Tsung, Hui-Chun Cheng, Peiyu Peng, and Ping-Chiang Lyu

Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan 300, ROC (yjsun@life.nthu.edu.tw)

Non-specific lipid transfer proteins (nsLTPs) bind to a variety of lipid molecules and catalyze their transfer across membranes [1]. Other biological functions for nsLTPs also have been proposed such as transfer phospholipids from liposomes or microsomes to mitochondria [2], transport cuticular components for the biosynthesis of surface wax [3], regulate fatty acid beta-oxidation in glyoxysomes [4] and exhibit resistance to avirulent and virulent pathogens in the plant defense system [5]. NsLTPs have been isolated from many plants including wheat, rice, barley, maize, peach, and apricot. NsLTPs are basic proteins (PI 8-10), disulfide-rich, with molecular weight 9 and 7 kDa (nsLTP1 & nsLTP2) [1]. We report here the crystal structures of rice nsLTP1 and fatty acid complexes have been determined by X-ray crystallography. We suggest that the structural plasticity of nsLTP1 manages the lipid binding in the rice nsLTP1 lipid complexes. The tunnel-like hydrophobic cavity inside nsLTP1 provides a space large enough to accommodate a long fatty acyl chain. The hydrophobic and hydrophilic interactions from three key residues, Arg44, Try79 and Ile81, were contributed in the lipid binding.

References

1 Kader, J.C., (1996) Annu. Rev. Plant Physiol. Plant Mol. Biol. 47, 627–654.

2 Breu, V., Guerbette, F., Kader, J. C., Kannangara, C. G., Svensson, B. & Wettstein-Knowles, P. (1989). Carlsberg. Res. Commun. 54, 81-84.

3 Sterk, P., Booij, H., Schellekens, G. A., Van Kammen, A. & De Vries, S. C. (1991). The Plant Cell 3, 907-921.

4 Tsuboi, S., Osafune, T., Nishimura, M. & Yamada, M. (1992). J. Biochem. 111, 500-508.

5 Maldonado, A. M., Doerner, P., Dixonk, R. A., Lamb, C. J. & Cameron, R. K., Nature (2002) 419, 399-403.