The non-specific lipid transfer proteins (nsLTPs) are multifunctional seed proteins engaged in several different physiological processes. The nsLTPs are stabilized by four disulfide bonds and exhibit a characteristic hydrophobic cavity, which is the primary lipid binding site. While these proteins are known to transfer lipids between membranes, the mechanism of lipid transfer has remained elusive. Four crystal structures of nsLTP from Solanum melongena, one in the apo-state and three myristic acid bound states were determined. Among the three lipid bound states, two lipid molecules were bound on the nsLTP surface at different positions and one was inside the cavity. The lipid-dependent conformational changes leading to opening of the cavity were revealed based on structural and spectroscopic data. The surface-bound lipid represented a transient intermediate state and the lipid ultimately moved inside the cavity through the cavity gate as revealed by molecular dynamics simulations. Two critical residues in the loop regions played possible 'gating' role in the opening and closing of the cavity. Antifungal activity and membrane permeabilization effect of nsLTP against Fusarium oxysporum suggested that it could possibly involve in bleaching out the lipids. Collectively, these studies support a model of lipid transfer mechanism by nsLTP via intermediate states.

中文翻译：

---

对非特异性脂质转移蛋白的脂质转移机制的结构见解。

非特异性脂质转移蛋白（nsLTPs）是参与多种不同生理过程的多功能种子蛋白。nsLTP通过四个二硫键稳定，并显示出特征性的疏水腔，这是主要的脂质结合位点。尽管已知这些蛋白质可在膜之间转移脂质，但脂质转移的机制仍然难以捉摸。测定了茄茄中nsLTP的四个晶体结构，其中一个处于脱辅基态，三个肉豆蔻酸键合态。在这三个脂质结合状态中，两个脂质分子在nsLTP表面上的不同位置结合，一个在腔体内。基于结构和光谱数据揭示了导致腔开放的脂质依赖性构象变化。表面结合的脂质代表瞬时的中间状态，并且脂质最终通过空腔门在空腔内移动，如分子动力学模拟所揭示的。回路区域中的两个关键残留物在型腔的打开和关闭中起到了可能的“门控”作用。nsLTP对尖孢镰刀菌的抗真菌活性和膜透化作用表明它可能参与了脂质的漂白。这些研究共同支持了nsLTP通过中间状态进行脂质转移机制的模型。nsLTP对尖孢镰刀菌的抗真菌活性和膜透化作用表明它可能参与了脂质的漂白。这些研究共同支持了nsLTP通过中间状态进行脂质转移机制的模型。nsLTP对尖孢镰刀菌的抗真菌活性和膜透化作用表明它可能与脂质的漂白有关。这些研究共同支持了nsLTP通过中间状态进行脂质转移机制的模型。