National Agri-Food Biotechnology Institute (NABI), Mohali, India.
National Agri-Food Biotechnology Institute (NABI), Mohali, India; Department of Biotechnology, Panjab University, Chandigarh, India.
J Biotechnol. 2020 Dec 20;324:103-111. doi: 10.1016/j.jbiotec.2020.09.026. Epub 2020 Sep 29.
Jujube (Ziziphus jujubaMill.), a deciduous tree, is well known for its medicinal and nutritional values. Being an extremophile, it has an excellent capability to survive under arid conditions with limited water availability. In this regard, studying the role of water transport regulating proteins such as Aquaporins (AQPs) in jujube is of great importance. Aquaporins, channel-forming proteins are known to have a significant role in the transport of water and many other small solutes in plants. In the present study, computational approaches have identified 36 AQPs, which comprised of 12 NIPs (Nodulin 26-like intrinsic proteins), 10 PIPs (Plasma membrane intrinsic proteins), 10 TIPs (Tonoplast intrinsic proteins), 3 SIPs (Small intrinsic proteins), and 1 XIP (uncharacterized intrinsic protein). Conserved features of AQPs like asparagines-proline-alanine (NPA) amino acid motifs, aromatic/arginine (ar/R) selectivity filters, and Frogger's residues, having a significant role in solute specificity and transport, were also predicted. Homology-based tertiary (3D) structures of AQP were also resolved using various tools, and subsequently, pore-lining residues have been identified using the 3D structures. The information of pore morphology, along with the conserved features provided through this work, will be helpful to predict solute specificity of AQPs. Analysis of transcriptomic data revealed the tissue-specific or ubiquitous expression of several AQPs in different tissues of jujube. Interestingly, TIP3-1 was found to have fruit specific expression whereas most of the AQPs have a relatively low expression. Based on the present study and previous reports, TIP3s seems to have a significant role in seed desiccation processes. The findings presented here provide pivotal insights into the functions of extremophile specific AQPs, to better understand the role of AQPs and, subsequently, the stress tolerance mechanism in jujube.
枣树（Ziziphus jujubaMill.）是一种落叶乔木，以其药用和营养价值而闻名。作为一种极端适应环境的生物，它具有在有限水资源的干旱条件下生存的卓越能力。在这方面，研究水运输调节蛋白（如 Aquaporins，AQP）在枣树中的作用非常重要。AQP 是一种形成通道的蛋白质，已知在植物中对水和许多其他小分子溶质的运输具有重要作用。在本研究中，通过计算方法鉴定出 36 个 AQP，包括 12 个 NIP（类豆球蛋白 26 内在蛋白）、10 个 PIP（质膜内在蛋白）、10 个 TIP（液泡膜内在蛋白）、3 个 SIP（小内在蛋白）和 1 个 XIP（未鉴定的内在蛋白）。还预测了 AQP 的保守特征，如天冬酰胺-脯氨酸-丙氨酸（NPA）氨基酸基序、芳香族/精氨酸（ar/R）选择性过滤器和在溶质特异性和运输中起重要作用的 Frogger 残基。还使用各种工具解析了基于同源性的 AQP 三级（3D）结构，并随后使用 3D 结构鉴定了孔衬残基。提供的孔形态信息以及通过这项工作提供的保守特征，将有助于预测 AQP 的溶质特异性。分析转录组数据显示，不同组织中的几种 AQP 在枣树的不同组织中具有组织特异性或普遍性表达。有趣的是，发现 TIP3-1 具有果实特异性表达，而大多数 AQP 的表达相对较低。基于本研究和以前的报告，TIP3s 似乎在种子干燥过程中具有重要作用。这里提出的发现为了解极端适应环境的 AQP 的功能提供了重要的见解，以更好地理解 AQP 的作用，以及随后在枣树中的应激耐受机制。
