PDBsum entry 1afh

Lipid binding protein

PDB id

1afh

Contents

			Protein chain

					93 a.a.

References listed in PDB file

Key reference

Title

Solution structure and lipid binding of a nonspecific lipid transfer protein extracted from maize seeds.

Authors

J.Gomar, M.C.Petit, P.Sodano, D.Sy, D.Marion, J.C.Kader, F.Vovelle, M.Ptak.

Ref.

Protein Sci, 1996, 5, 565-577. [DOI no: 10.1002/pro.5560050402]

PubMed id

8845747

Abstract

The three-dimensional solution structure of a nonspecific lipid transfer protein extracted from maize seeds determined by 1H NMR spectroscopy is described. This cationic protein consists of 93 amino acid residues. Its structure was determined from 1,091 NOE-derived distance restraints, including 929 interresidue connectivities and 197 dihedral restraints (phi, psi, chi 1) derived from NOEs and 3J coupling constants. The global fold involving four helical fragments connected by three loops and a C-terminal tail without regular secondary structures is stabilized by four disulfide bridges. The most striking feature of this structure is the existence of an internal hydrophobic cavity running through the whole molecule. The global fold of this protein, very similar to that of a previously described lipid transfer protein extracted from wheat seeds (Gincel E et al., 1994, Eur J Biochem 226:413-422) constitutes a new architecture for alpha-class proteins. 1H NMR and fluorescence studies show that this protein forms well-defined complexes in aqueous solution with lysophosphatidylcholine. Dissociation constants, Kd, of 1.9 +/- 0.6 x 10(-6) M and > 10(-3) M were obtained with lyso-C16 and -C12, respectively. A structure model for a lipid-protein complex is proposed in which the aliphatic chain of the phospholipid is inserted in the internal cavity and the polar head interacts with the charged side chains located at one end of this cavity. Our model for the lipid-protein complex is qualitatively very similar to the recently published crystal structure (Shin DH et al., 1995, Structure 3:189-199).



	Figure 4. Fig. 4. Stereo view of the pore throughthe maize ns-LTP. The backbone isrepresented as a tube colored in cyan, hydrophobic residues lining the cavity are colored in yellow, basic residuesin pink, acidic residuesin blue, Tyr 17 and Tyr 81 in green, cys- teinesresiduesinblue-green,andpinkcirclesshowthesurface of thecavity,calculatedwithth PORE program(Smartet al., 1993).		Figure 10. Fig. 10. Sequencealignment of HPS,wheat.andmaizens-LPT.Secondarystructureelementsareindicated.Arrowcorresponds IO a 8-strand.

PROCHECK

	Headers