IFM, Linköping University, 581 83 Linköping, Sweden.
Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, FI-20520 Turku, Finland.
Plant Physiol Biochem. 2014 Feb;75:55-69. doi: 10.1016/j.plaphy.2013.12.001. Epub 2013 Dec 17.
The non-specific lipid transfer proteins (nsLTPs) are characterized by a compact structure with a central hydrophobic cavity very suitable for binding hydrophobic ligands, such as lipids. The nsLTPs are encoded by large gene families in all land plant lineages, but seem to be absent from green algae. The nsLTPs are classified to different types based on molecular weight, sequence similarity, intron position or spacing between the cysteine residues. The Type G nsLTPs (LTPGs) have a GPI-anchor in the C-terminal region which may attach the protein to the exterior side of the plasma membrane. Here, we present the first characterization of nsLTPs from an early diverged plant, the moss Physcomitrella patens. Moss LTPGs were heterologously produced and purified from Pichia pastoris. The purified moss LTPGs were found to be extremely heat stable and showed a binding preference for unsaturated fatty acids. Structural modeling implied that high alanine content could be important for the heat stability. Lipid profiling revealed that cutin monomers, such as C16 and C18 mono- and di-hydroxylated fatty acids, could be identified in P. patens. Expression of a moss LTPG-YFP fusion revealed localization to the plasma membrane. The expressions of many of the moss LTPGs were found to be upregulated during drought and cold treatments.
非特异性脂质转移蛋白（nsLTPs）的结构紧凑，中央有一个疏水腔，非常适合结合疏水性配体，如脂质。nsLTPs 编码基因家族在所有陆生植物谱系中都很大，但似乎不存在于绿藻中。nsLTPs 根据分子量、序列相似性、内含子位置或半胱氨酸残基之间的间隔分为不同的类型。G 型 nsLTP（LTPGs）在 C 末端区域具有一个 GPI-锚定，可能将蛋白质附着到质膜的外侧。在这里，我们首次对早期分化植物苔藓Physcomitrella patens 的 nsLTPs 进行了表征。从毕赤酵母中异源生产和纯化了苔藓 LTPGs。纯化的苔藓 LTPGs 表现出极高的热稳定性，并显示出对不饱和脂肪酸的结合偏好。结构建模表明，高丙氨酸含量可能对热稳定性很重要。脂质分析表明，在 P. patens 中可以鉴定出角质单体，如 C16 和 C18 单羟基和二羟基脂肪酸。苔藓 LTPG-YFP 融合蛋白的表达显示定位于质膜。发现许多苔藓 LTPGs 的表达在干旱和寒冷处理时上调。
