Reference "High-resolution crystal structure of the non-specific lipid-transfer protein from maize seedlings"

Reference ID

7275

Title

High-resolution crystal structure of the non-specific lipid-transfer protein from maize seedlings

Source

Structure (London, England), 1995, vol. 3, pp. 189-199

Authors (5)

Shin-D-H	Lee-J-Y
Hwang-K-Y	Kim-K-K
Suh-S-W

Abstract

BACKGROUND: The movement of lipids between membranes is aided by lipid-transfer
proteins (LTPs). Some LTPs exhibit broad specificity, transferring many classes
of lipids, and are termed non-specific LTPs (ns-LTPs). Despite their apparently
similar mode of action, no sequence homology exists between mammalian and plant
ns-LTPs and no three-dimensional structure has been reported for any plant ns-
LTP. RESULTS: We have determined the crystal structure of ns-LTP from maize
seedlings by multiple isomorphous replacement and refined the structure to 1.9 A
resolution. The protein comprises a single compact domain with four alpha-
helices and a long C-terminal region. The eight conserved cysteines form four
disulfide bridges (assigned as Cys4-Cys52, Cys14-Cys29, Cys30-Cys75, and Cys50-
Cys89) resolving the ambiguity that remained from the chemical determination of
pairings in the homologous protein from castor bean. Two of the bonds, Cys4-
Cys52 and Cys50-Cys89, differ from what would have been predicted from sequence
alignment with soybean hydrophobic protein. The complex between maize ns-LTP and
hexadecanoate (palmitate) has also been crystallized and its structure refined
to 1.8 A resolution. CONCLUSIONS: The fold of maize ns-LTP places it in a new
category of all-alpha-type structure, first described for soybean hydrophobic
protein. In the absence of a bound ligand, the protein has a tunnel-like
hydrophobic cavity, which is large enough to accommodate a long fatty acyl
chain. In the structure of the complex with palmitate, most of the acyl chain is
buried inside this hydrophobic cavity.