School of Chemistry, University of Hyderabad, Hyderabad, 500046, India.
School of Chemistry, University of Hyderabad, Hyderabad, 500046, India.
Phytochemistry. 2022 Sep;201:113251. doi: 10.1016/j.phytochem.2022.113251. Epub 2022 May 27.
Much of the plant lectin research was focused on these proteins from seeds, whereas lectins from other plant tissues have been less investigated. Although presence of lectins in the phloem exudate of Cucurbitaceae species was reported over 40 years ago, only a few proteins from this family have been purified and characterized with respect to ligand binding properties, primary and secondary structures, while no 3D structure of a member of this family is known so far. Unlike lectins from other plant families and sources (e.g., seeds and tubers), which exhibit specificity towards different carbohydrate structures, all the Cucurbitaceae phloem exudate lectins characterized so far have been shown to recognize only chitooligosaccharides or glycans containing chitooligosaccharides. Interestingly, some of these proteins also bind various types of RNAs, suggesting that they may also play a role in the transport of RNA information molecules in the phloem. The present review gives an overview of the current knowledge of Cucurbitaceae phloem exudate lectins with regard to their purification, determination of primary and secondary structures, elucidation of thermodynamics and kinetics of carbohydrate binding and computational modeling to get information on their 3D structures. Finally, future perspectives of research on this important class of proteins are considered.
植物凝集素的研究主要集中在这些来自种子的蛋白质上，而来自其他植物组织的凝集素则研究较少。尽管 40 多年前就有报道称葫芦科植物韧皮部分泌物中存在凝集素，但目前仅对该家族的少数几种蛋白质进行了纯化和配体结合特性、一级和二级结构的特性研究，而到目前为止，还没有该家族成员的三维结构。与来自其他植物科和来源（例如种子和块茎）的凝集素不同，后者对不同的碳水化合物结构具有特异性，迄今为止所表征的所有葫芦科韧皮部分泌物凝集素都被证明仅识别壳寡糖或含有壳寡糖的聚糖。有趣的是，其中一些蛋白质还结合各种类型的 RNA，这表明它们也可能在韧皮部中 RNA 信息分子的运输中发挥作用。本文综述了葫芦科韧皮部分泌物凝集素的最新研究进展，包括它们的纯化、一级和二级结构的测定、碳水化合物结合的热力学和动力学的阐明以及计算建模，以获取有关其三维结构的信息。最后，考虑了对这一重要蛋白质类别的未来研究展望。
