K-Means聚类分析法筛选柠檬香茅茎叶差异蛋白及鉴定

柠檬香茅含有大量的香茅精油,运用十分广泛,然而其茎、叶的精油含量却相差悬殊。 为探索柠檬香茅精油代谢相关的蛋白途径,本文对柠檬香茅旗叶、成熟叶及茎秆等材料进行精油含量、总蛋白含量测定及双向凝胶电泳(2-DE)表达谱分析,运用k-means聚类分析方法对2-DE电泳中差异蛋白斑点的丰度、等电点和相对分子质量进行聚类分析和讨论,结果表明,旗叶和茎秆上调表达的蛋白质斑点的聚类对于相对分子质量变化敏感,成熟叶上调表达蛋白质斑点对于丰度的变化较为敏感。 预测了精油代谢功能相关的蛋白质斑点15个,挖取预测蛋白质斑点通过基质辅助激光解吸电离飞行时间质谱(MALDI-TOF/TOF-MS)成功鉴定了9个蛋白质。 本研究为柠檬香茅精油的蛋白代谢途径提供新的基础信息及研究思路。

Screening and Identification of Differential Proteins in Cymbopogon citratus Stems and Leaves by K-Means Clustering Analysis

The lemongrass plant contains a huge amount of essential oil which had a wide application. It was found that there were great differences between the stem and leaves of lemongrass in essential oil yields. In this paper, we investigated the differential expression protein spots in two-dimensional electrophoresis (2-DE) of lemongrass stem and leaves via K-means clustering. Three parts of lemongrass, flag-leaf, mature-leaf and stem, which were significant different in essential oil contents, were taken to detect the total protein content and analysize the protein expression profiles by 2-DE. K-means clustering of different protein spots was carried out on abundance, isoelectric point (pI) and molecular mass. It was found that the total protein content of flag-leaf and mature-leaf was higher than that of stem, and the total protein content of flag leaf and mature-leaf had little difference. Cluster analysis of the abundance, isoelectric point (pI) and molecular mass of different protein spots in three parts of lemongrass showed that the up-regulated protein spots in flag-leaf and stem were sensitive to molecular weight changes, and the up-regulated protein spots in mature-leaf were more sensitive to abundance changes. Based on this, 15 protein pots were selected and 9 proteins were successfully identified by matrix-assisted laser desorption/ionization (MALDI-TOF/TOF-MS). Our study provides new basic information and research perspective of protein pathway of Cymbopogon citratus essential oil metabolism.