The crystal structure of a wheat nonspecific lipid transfer protein (ns-LTP1) complexed with two molecules of phospholipid at 2.1 Å resolution

Authors


E. Pebay-Peyroula, Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS, 41 Avenue Jules Horowitz, 38027 Grenoble cedex 1, France. Tel.: 33 (0) 4 76 88 95 83, Fax: 33 (0) 4 76 88 54 94, E-mail: pebay@ibs.fr

Abstract

Nonspecific lipid transfer proteins (ns-LTP1) form a multigenic protein family in plants. In vitro they are able to bind all sort of lipids but their function, in vivo, remains speculative. A ns-LTP1 isolated from wheat seed was crystallized in the presence of lyso-myristoyl-phosphatidylcholine (LMPC). The structure was solved by molecular replacement and refined to 2.1 Å resolution to an R-factor of 16.3% and a free R-factor of 21.3%. It reveals for the first time that the protein binds two LMPC molecules that are inserted head to tail in a hydrophobic cavity. A detailed study of the structure leads to the conclusion that there are two lipid-binding sites, one of which shows a higher affinity for the LMPC than the other. Comparison with other structures of lipid-bound ns-LTP1 suggests that the presence of two binding sites is a general feature of plant ns-LTP1.

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