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

Dong Hae Shin, Jae Young Lee, Kwang Yeon Hwang, Kyeong Kyu Kim, Se Won Suh

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195 Citations (Scopus)

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 Å resolution. The protein comprises a single compact domain with four α-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 Å resolution. Conclusions: The fold of maize ns-LTP places it in a new category of all-α-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.

Original languageEnglish
Pages (from-to)189-199
Number of pages11
JournalStructure
Volume3
Issue number2
Publication statusPublished - 1995 Dec 1
Externally publishedYes

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Keywords

  • Lipid-transfer protein
  • Maize protein
  • X-ray structure

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

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