title: A rice lipid transfer protein binds to plasma membrane proteinaceous sites.
abstract: Nonspecific lipid transfer protein (nsLTP) is usually basic and secreted low-molecular-mass protein in plants. The 3-D structure of nsLTP1 resembles that of elicitin produced by the plant pathogen Phytophthora cryptogea, which can bind to the plant plasma membrane putative receptor and activate the downstream responses. It is inferred that nsLTP1 may have similar binding sites on the plasma membranes. In this work, rice recombinant protein TRX-nsLTP110 labeled with (125)I was shown to bind to rice plasma membrane preparations in a saturable curve, with an apparent K(d) of 13.6 nM and B(max) of 150 fmol/mg proteins. Competition experiments revealed that the binding of TRX-nsLTP110 was specific, in contrast to the nonspecific binding of the fusion tag thioredoxin. Protease treatment assay showed that the binding sites were proteinaceous. Our results suggest that the binding sites of nsLTPs on plasma membranes may be ubiquitous in the plant kingdom. They may be competed out from the binding sites under pathogen attack, supporting a role for nsLTP1 in host defense response to pathogens.
authors.affiliation: State Key Laboratory of Genetic Engineering, Department of Biochemistry and Molecular Biology, School of Life Sciences, Fudan University, Handan Road 220#, Shanghai 200433, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
authors.forename: Yuanli
authors.initials: Y
authors.lastname: Li
authors.forename: Kaiming
authors.initials: K
authors.lastname: Cao
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Ge
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C030363:lipid transfer protein