植物水孔蛋白

水孔蛋白的发现丰富了人们对水分跨膜转运机制的认识,植物水孔蛋白在水分吸收、渗透调节、细胞的伸长和气孔运动等方面都有重要作用。现对植物水孔蛋白的结构特征、多样性、生理学功能、活性调节以及水孔蛋白与环境因子的关系等方面的研究进展进行综述。     

植物水孔蛋白研究进展

水孔蛋白是植物重要的膜功能蛋白,不仅介导植物各组织间水分的高效转运,还参与植物体内其他物质的跨膜转运,同时在植物光合作用、生长发育、免疫应答以及信号转导等生理过程中也发挥重要作用。本文主要综述了植物水孔蛋白结构特征和分类,多种生理功能,以及其转录水平和转录后水平活性调节等方面的最新研究进展,并就如何系统全面地开展水孔蛋白参与植物生长发育过程的分子调控机制研究提出展望。植物水孔蛋白的深入研究有助于阐明植物体内物质转运的分子机理及其生理作用机制,对指导农业生产中作物的生长发育调控有重要理论意义。     

植物水孔蛋白最新研究进展

水孔蛋白(aquaporin,AQP)是高效转运水分子的膜内在蛋白,具有丰富的多样性,在调控植物的水分关系中有重要作用．介绍了AQP的分类、结构特征及其在植物生长发育过程中的多种生理功能和AQP活性的各种调控方式．综述了水分胁迫和盐胁迫等逆境条件及脱落酸、赤霉素和乙烯等植物激素对AQP基因表达调控等方面的研究进展．     

植物蔗糖转运蛋白及其生理功能的研究进展

高等植物通过光合作用产生蔗糖,并以蔗糖形式将同化碳源分配到植物各组织器官中,蔗糖的跨膜转运需要蔗糖转运蛋白的参与。目前,已有研究表明蔗糖转运蛋白广泛存在于高等植物体内,主要在种子、花器、叶肉细胞、韧皮部和根等器官中发挥作用,而通过亚细胞定位可以发现,蔗糖转运蛋白主要定位在细胞的液泡膜及细胞质膜上。综述了国内外对蔗糖转运蛋白的发现、结构、分类、生理功能、功能验证及定位等方面的研究内容,分析了研究蔗糖转运蛋白的意义及目前存在的一些问题,旨为更好地理解蔗糖转运蛋白在植物体内的作用机制做铺垫。     

植物细胞外源蛋白亚细胞定位的机制及其应用

为将不同的生理功能区隔化,植物细胞分化出具有特异性结构特征的细胞器.分化的细胞内膜系统和分子水平的蛋白质转运调控机制为外源蛋白亚细胞定位表达提供了显著的有利条件.当蛋白质被加载适当的定位信号或启动子时,蛋白质的分选途径便确定下来,同时决定蛋白质的表达终点.本文根据相关研究主题分析了蛋白质亚细胞定位机制,重点阐述包括ER腔、质外体、液泡、蛋白体等细胞器和内膜结构在内的蛋白定位因素,同时探讨了目前蛋白定位因素的应用情况.本文确定亚细胞定位因素将成为植物基因工程领域控制亚细胞水平表达的重要技术策略.     

植物多药和有毒化合物排出转运蛋白研究进展

植物在生长及适应环境的过程中会吸收很多有益或有害的物质,自身也会产生大量代谢物,植物对这些物质的转运是植物生长发育及适应环境的重要环节,有多种转运蛋白家族参与其中。多药和有毒化合物排出转运蛋白(MATEs)是生物体中重要的转运蛋白家族之一,而植物中MATE基因的丰富程度要远远高于其他生物。根据植物MATEs的蛋白结构,这些基因被分为4个主要的亚家族,即MATE I,MATEⅡ,MATEⅢ和MATE IV。同一亚家族或同一MATE基因簇的基因还具有相同或相似的功能。植物MATEs定位于细胞的各种生物膜上,如细胞质膜、液泡膜、高尔基膜及囊泡膜等。此外,一些MATEs的表达还具有组织特异性,它们转运的底物也具有多样性和特异性,使得MATEs呈现出多种生物学功能。它们在外源性物质的排出、次生代谢产物的转运和累积、铁转运、铝脱毒和植物激素信号传递及植物的抗病性等方面都起着重要作用。该文对MATEs的发现、基因分类、亚细胞定位及生理功能等方面进行了概述,对深入研究该基因家族提供了思路,对该基因家族的应用进行了展望。     

拟南芥ABC转运类蛋白家族的分子进化、表达模式和蛋白功能网络预测分析

ABC转运蛋白又称腺苷三磷酸结合盒转运蛋白(ATP-binding cassette transporters),该基因家族是目前已知最大、最古老的蛋白家族之一,在植物中ABC转运蛋白种类繁多、结构复杂、功能多样,涉及植物一切的生命活动过程。本研究系统介绍了拟南芥中131个ABC转运蛋白的亚家族分类、系统命名、蛋白大小以及蛋白亚细胞定位等基因信息,在此基础上,分析了ABC转运蛋白基因在染色体分布以及进化过程中发生的复制事件;其次在47个组织器官或发育阶段中聚类分析了ABC转运蛋白的表达模式和各个亚家族分布规律,结果表明ABC转运蛋白基因的表达具有明显的组织特异性和时空特异性,说明在进化过程中该类蛋白功能也进一步发生分化;我们以花药发育过程为例,说明ABC转运蛋白在花药发育过程中具有较高的协调性,在时空和组织上表达受到严格的调控;最后我们分析了ABC转运蛋白亚家族内部和各个亚家族之间可能存在的蛋白相互作用关系,推测ABC半分子转运蛋白形成同源或异源二聚体发挥功能的可能性,进一步说明ABC转运蛋白在蛋白互作水平上也存在功能多样性和严格的调控关系。     

水孔蛋白在细胞延长、盐胁迫和光合作用中的作用

水孔蛋白属于一个高度保守的、能够进行跨生物膜水分运输的通道蛋白MIP家族。水孔蛋白作为膜水通道,在控制细胞和组织的水含量中扮演重要角色。本研究的重点是属于PIP亚家族的GhPIP1;2和属于TIP亚家族的γTIP1在植物细胞延长中的作用。使用特异基因探针的Northern杂交和实时荧光PCR技术证明GhPIP1;2和GhγTIP1主要在棉花纤维延长过程中显著表达,且最高表达量在开花后5d。在细胞延长过程中,GhPIP1;2和GhγTIP1表达显著,表明它们在促使水流迅速进入液泡这一过程中扮演重要角色。而且也研究了盐胁迫植物中钙离子对水孔蛋白的影响。分别或一起用NaCl或CaCl2处理原生质体或细胞质膜。结果发现在盐胁迫条件下,水渗透率值在原生质体和质膜颗粒中都下降了,同时PIP1水孔蛋白的含量也下降了,表明NaCl对水孔蛋白的功能和含量有抑制作用。同时也观察了Ca2+的两种不同的作用。感知胁迫的胞质中游离钙离子浓度的增加可能导致水孔蛋白的关闭。而过剩的钙离子将导致水孔蛋白的上游调控。同时实验已经证明大麦的一类水孔蛋白-HvPIP2;1有更高的水和CO2转移率。本研究的目标是确定负责转运水和CO2的关键水孔蛋白...     

植物抗旱和耐重金属基因工程研究进展

干旱和重金属污染严重影响植物的生长发育.植物耐逆相关基因的克隆和功能鉴定研究,为通过基因工程途径提高植物的抗逆性奠定了理论基础.水分亏缺、高盐、低温和重金属胁迫都能诱导LEA(late embryogenesis abundant protein)基因的表达.转基因研究表明,LEA蛋白具有抗旱保护作用、离子结合特性以及抗氧化活性;水孔蛋白存在于细胞膜和液泡膜上,在细胞乃至整个植物体水分吸收和运输过程中发挥重要作用.干旱和盐胁迫促进水孔蛋白基因转录物的积累.过量表达水孔蛋白可增强水分吸收和运输,提高植物的抗旱能力.金属转运蛋白参与重金属离子的吸收、运输和累积等过程.这些蛋白基因在改良草坪草植物的抗旱节水和耐重金属能力等方面具有潜在的应用价值.     

质膜转运蛋白及其与植物耐盐性关系研究进展

植物细胞质膜有两种主要功能：(1)溶质运输(进出细胞),溶质运输主要由转运蛋白完成;(2)信号传导,即接收信号并引发细胞生理生化响应。盐分过多对植物的伤害主要是离子毒害。质膜转运蛋白活性对环境变化能做出迅速响应。本文简要叙述了植物细胞质膜转运蛋白类型、分子特性、生理功能及其活性调节。介绍了植物细胞质膜H+_ATPase、质膜氧化还原系统、质膜离子载体和离子通道对盐胁迫的响应及其这些响应与植物耐盐性之间的关系。     

Plant aquaporins: Roles in plant physiology

Background

Aquaporins are membrane channels that facilitate the transport of water and small neutral molecules across biological membranes of most living organisms.

Scope of review

Here, we present comprehensive insights made on plant aquaporins in recent years, pointing to their molecular and physiological specificities with respect to animal or microbial counterparts.

Major conclusions

In plants, aquaporins occur as multiple isoforms reflecting a high diversity of cellular localizations and various physiological substrates in addition to water. Of particular relevance for plants is the transport by aquaporins of dissolved gases such as carbon dioxide or metalloids such as boric or silicic acid. The mechanisms that determine the gating and subcellular localization of plant aquaporins are extensively studied. They allow aquaporin regulation in response to multiple environmental and hormonal stimuli. Thus, aquaporins play key roles in hydraulic regulation and nutrient transport in roots and leaves. They contribute to several plant growth and developmental processes such as seed germination or emergence of lateral roots.

General significance

Plants with genetically altered aquaporin functions are now tested for their ability to improve plant resistance to stresses. This article is part of a Special Issue entitled Aquaporins.     

Isozymes of plant hexokinase: occurrence, properties and functions

Hexokinase (HK) occurs in all phyla, as an enzyme of the glycolytic pathway. Its importance in plant metabolism has emerged with compelling evidence that its preferential substrate, glucose, is both a nutrient and a signal molecule that controls development and expression of different classes of genes. A variety of plant tissues and organs have been shown to express multiple HK isoforms with different kinetic properties and subcellular localizations. Although plant HK is known to fulfill a catalytic function and act as a glucose sensor, the physiological relevance of plural isoforms and their contribution to either function are still poorly understood. We review here the current knowledge and hypotheses on the physiological roles of plant HK isoforms that have been identified and characterized. Recent findings provide hints on how the expression patterns, biochemical properties and subcellular localizations of HK isoforms may relate to their modes of action. Special attention is devoted to kinetic, mutant and transgenic data on HKs from Arabidopsis thaliana and the Solanaceae potato, tobacco, and tomato, as well as HK gene expression data from Arabidopsis public DNA microarray resources. Similarities and differences to known properties of animal and yeast HKs are also discussed as they may help to gain further insight into the functional adaptations of plant HKs.     

DM3Loc: multi-label mRNA subcellular localization prediction and analysis based on multi-head self-attention mechanism

Subcellular localization of messenger RNAs (mRNAs), as a prevalent mechanism, gives precise and efficient control for the translation process. There is mounting evidence for the important roles of this process in a variety of cellular events. Computational methods for mRNA subcellular localization prediction provide a useful approach for studying mRNA functions. However, few computational methods were designed for mRNA subcellular localization prediction and their performance have room for improvement. Especially, there is still no available tool to predict for mRNAs that have multiple localization annotations. In this paper, we propose a multi-head self-attention method, DM3Loc, for multi-label mRNA subcellular localization prediction. Evaluation results show that DM3Loc outperforms existing methods and tools in general. Furthermore, DM3Loc has the interpretation ability to analyze RNA-binding protein motifs and key signals on mRNAs for subcellular localization. Our analyses found hundreds of instances of mRNA isoform-specific subcellular localizations and many significantly enriched gene functions for mRNAs in different subcellular localizations.     

Advances in functional regulation mechanisms of plant aquaporins: Their diversity,gene expression,localization, structure and roles in plant soil-water relations (Review)

Aquaporins are important molecules that control the moisture level of cells and water flow in plants. Plant aquaporins are present in various tissues, and play roles in water transport, cell differentiation and cell enlargement involved in plant growth and water relations. The insights into aquaporins’ diversity, structure, expression, post-translational modification, permeability properties, subcellular location, etc., from considerable studies, can lead to an understanding of basic features of the water transport mechanism and increased illumination into plant water relations. Recent important advances in determining the structure and activity of different aquaporins give further details on the mechanism of functional regulation. Therefore, the current paper mainly focuses on aquaporin structure-function relationships, in order to understand the function and regulation of aquaporins at the cellular level and in the whole plant subjected to various environmental conditions. As a result, the straightforward view is that most aquaporins in plants are to regulate water flow mainly at cellular scale, which is the most widespread general interpretation of the physiological and functional assays in plants.     

Plant NB-LRR immune receptors: from recognition to transcriptional reprogramming

Both plants and animals contain nucleotide-binding domain and leucine-rich repeat (NB-LRR)-type immune receptors that function during defense against pathogens. Unlike animal NB-LRRs that recognize general pathogen or microbe-associated molecular patterns (PAMPs or MAMPs), plant NB-LRR immune receptors have evolved the ability to specifically recognize a wide range of effector proteins from different pathogens. Recent research has revealed that plant NB-LRRs are incredibly adaptive in their ways of pathogen recognition and defense initiation. This review focuses on the remarkable variety of functions, recognition mechanisms, subcellular localizations, and host factors associated with plant NB-LRR immune receptors.     

Aquaporin water channels: molecular mechanisms for human diseases

Although water is the major component of all biological fluids, the molecular pathways for water transport across cell membranes eluded identification until the discovery of the aquaporin family of water channels. The atomic structure of mammalian AQP1 illustrates how this family of proteins is freely permeated by water but not protons (hydronium ions, H3O+). Definition of the subcellular sites of expression predicted their physiological functions and potential clinical disorders. Analysis of several human disease states has confirmed that aquaporins are involved in multiple different illnesses including abnormalities of kidney function, loss of vision, onset of brain edema, starvation, and arsenic toxicity.     

Multifaceted roles of aquaporins as molecular conduits in plant responses to abiotic stresses

Abiotic stress has become a challenge to food security due to occurrences of climate change and environmental degradation. Plants initiate molecular, cellular and physiological changes to respond and adapt to various types of abiotic stress. Understanding of plant response mechanisms will aid in strategies aimed at improving stress tolerance in crop plants. One of the most common and early symptoms associated with these stresses is the disturbance in plant–water homeostasis, which is regulated by a group of proteins called “aquaporins”. Aquaporins constitute a small family of proteins which are classified further on the basis of their localization, such as plasma membrane intrinsic proteins, tonoplast intrinsic proteins, nodulin26-like intrinsic proteins (initially identified in symbiosomes of legumes but also found in the plasma membrane and endoplasmic reticulum), small basic intrinsic proteins localized in ER (endoplasmic reticulum) and X intrinsic proteins present in plasma membrane. Apart from water, aquaporins are also known to transport CO₂, H₂O₂, urea, ammonia, silicic acid, arsenite and wide range of small uncharged solutes. Besides, aquaporins also function to modulate abiotic stress-induced signaling. Such kind of versatile functions has made aquaporins a suitable candidate for development of transgenic plants with increased tolerance toward different abiotic stress. Toward this endeavor, the present review describes the versatile functions of aquaporins in water uptake, nutrient balancing, long-distance signal transfer, nutrient/heavy metal acquisition and seed development. Various functional genomic studies showing the potential of specific aquaporin isoforms for enhancing plant abiotic stress tolerance are summarized and future research directions are given to design stress-tolerant crops.     

Advances in functional regulation mechanisms of plant aquaporins: their diversity, gene expression, localization, structure and roles in plant soil-water relations (Review)

Aquaporins are important molecules that control the moisture level of cells and water flow in plants. Plant aquaporins are present in various tissues, and play roles in water transport, cell differentiation and cell enlargement involved in plant growth and water relations. The insights into aquaporins' diversity, structure, expression, post-translational modification, permeability properties, subcellular location, etc., from considerable studies, can lead to an understanding of basic features of the water transport mechanism and increased illumination into plant water relations. Recent important advances in determining the structure and activity of different aquaporins give further details on the mechanism of functional regulation. Therefore, the current paper mainly focuses on aquaporin structure-function relationships, in order to understand the function and regulation of aquaporins at the cellular level and in the whole plant subjected to various environmental conditions. As a result, the straightforward view is that most aquaporins in plants are to regulate water flow mainly at cellular scale, which is the most widespread general interpretation of the physiological and functional assays in plants.     

Protein localization as a principal feature of the etiology and comorbidity of genetic diseases

Proteins targeting the same subcellular localization tend to participate in mutual protein–protein interactions (PPIs) and are often functionally associated. Here, we investigated the relationship between disease‐associated proteins and their subcellular localizations, based on the assumption that protein pairs associated with phenotypically similar diseases are more likely to be connected via subcellular localization. The spatial constraints from subcellular localization significantly strengthened the disease associations of the proteins connected by subcellular localizations. In particular, certain disease types were more prevalent in specific subcellular localizations. We analyzed the enrichment of disease phenotypes within subcellular localizations, and found that there exists a significant correlation between disease classes and subcellular localizations. Furthermore, we found that two diseases displayed high comorbidity when disease‐associated proteins were connected via subcellular localization. We newly explained 7584 disease pairs by using the context of protein subcellular localization, which had not been identified using shared genes or PPIs only. Our result establishes a direct correlation between protein subcellular localization and disease association, and helps to understand the mechanism of human disease progression.