PRGL：非洲菊细胞壁中一种含GASA结构域的富脯氨酸蛋白

PRPs（Proline-Rich proteins）是植物细胞壁蛋白,在结构上具有一个富含脯氨酸和羟脯氨酸重复序列的区域,其表达多受机械伤害及各种环境胁迫的刺激．而GASA（Gibberellic Acid Stimulated Arabidopsis,GASA）蛋白具有一个含12个半胱氨酸的C-端保守区域,这类蛋白多定位于细胞壁,且其表达多受GAs（Gibberellins）的调节．在法国菜豆（Phaseolus vulgaris）中,由2个独立的基因分别编码的PRP与GASA类似蛋白组成一个双元组分的几丁质受体蛋白,该蛋白与植物一病原物的相互作用有关．本文从非洲菊（Gerberahybrida）中克隆了一个完整的cDNA序列PRGL（Proline-RichGASA-like）,该基因编码的多肽包含了PRP和GASA类似结构域．实验表明,PRGL在结构上以及基因表达的调节方面都同时具有PRPs和GASA两类蛋白质的特征,是一类新的蛋白质．     

豌豆蚜唾液蛋白家族的克隆及在不同发育阶段的表达

豌豆蚜Acyrthosiphon pisum是一种重要的刺吸式害虫, 其分泌的唾液对取食寄主植物和传播植物病毒有重要的作用。为了探讨蚜虫唾液蛋白的功能, 本研究克隆了在豌豆蚜唾液腺高表达的一个未知功能的蛋白家族, 该家族包括13个基因, 编码14种蛋白, 其中4个基因在唾液腺高表达。这个家族是蚜虫特有的蛋白家族, 富含半胱氨酸, 有14个半胱氨酸高度保守, 其中6个半胱氨酸形成3个保守的CXXC结构域。通过与基因组比对, 发现这个家族的基因没有内含子, 分布在基因组的9个scaffold上。用半定量逆转录PCR检测了每个成员在豌豆蚜不同发育阶段的表达, 结果显示这个家族没有发育阶段特异性。推测这个家族的表达可能具有组织特异性, 有氧化还原酶或DNA甲基化酶的功能。     

植物类金属硫蛋白半胱氨酸富含区结构的建模

详细了解蛋白质的三级结构信息有助于理解其生物学功能。随着植物基因组研究的进展 ,已发现了 50多个植物类金属硫蛋白 (Metallothionein_Like ,MT_L)基因。但至今只有少数几个MT_L蛋白得到了纯化 ,而其结构尚无报道 ,因此有必要建立分析这类蛋白结构特征的方法。本研究根据已知的哺乳动物MT的结构数据 ,分析得出了CXC、CXXC模式和金属 硫络合簇结构原子间的距离限制条件 ,并用距离几何算法计算得出预测蛋白可能的构象 ;然后通过统计分析筛选出目标函数值显著较小、构象能低的结构作为这些蛋白半胱氨酸富含区的预测结构 ,由此建成了适合于植物类金属硫蛋白半胱氨酸富含区的结构预测方法。从应用该方法正确地预测出了已知结构的蓝蟹MT的结构来看 ,该方法是可行的。并用该方法预测了油菜MT_L蛋白的半胱氨酸富含区的结构。     

植物类金属硫蛋白半胱氨酸富含区结构的建模

详细了解蛋白质的三级结构信息有助于理解其生物学功能.随着植物基因组研究的进展,已发现了50多个植物类金属硫蛋白(Metallothionein-Like, MT-L)基因.但至今只有少数几个MT-L蛋白得到了纯化,而其结构尚无报道,因此有必要建立分析这类蛋白结构特征的方法.本研究根据已知的哺乳动物MT的结构数据,分析得出了CXC、CXXC模式和金属-硫络合簇结构原子间的距离限制条件,并用距离几何算法计算得出预测蛋白可能的构象;然后通过统计分析筛选出目标函数值显著较小、构象能低的结构作为这些蛋白半胱氨酸富含区的预测结构,由此建成了适合于植物类金属硫蛋白半胱氨酸富含区的结构预测方法.从应用该方法正确地预测出了已知结构的蓝蟹MT的结构来看,该方法是可行的.并用该方法预测了油菜MT-L蛋白的半胱氨酸富含区的结构.     

植物富含半胱氨酸蛋白的研究进展

富含半胱氨酸蛋白（cystein-rich proteins,CRPs）是动植物中广泛存在的一类小的分泌性蛋白,具有广泛的生物学功能,如防御、蛋白酶抑制、重金属解毒等。人们在深入研究植物CRPs防御功能的同时,发现CRPs还参与调节植物的生长、发育、生殖等。本文综述了植物CRPs的分类、结构及其在植物生长发育、生殖信号转导等方面的研究进展。     

植物富含半胱氨酸蛋白的研究进展

富含半胱氨酸蛋白(cystein-rich proteins,CRPs)是动植物中广泛存在的一类小的分泌性蛋白,具有广泛的生物学功能,如防御、蛋白酶抑制、重金属解毒等。人们在深入研究植物CRPs防御功能的同时,发现CRPs还参与调节植物的生长、发育、生殖等。本文综述了植物CRPs的分类、结构及其在植物生长发育、生殖信号转导等方面的研究进展。     

基于半胱氨酸排列方式的植物类金属硫蛋白的分类与命名法

随着植物基因组研究的进展,在基因库和蛋白库登录的植物类金属２硫蛋白基因已超过５０个,接近金属硫蛋白总数的１／３,而且有不断上升的趋势。鉴于目前植物类金属２硫蛋白命名与分灰随意性太大,很有必要建立一个统一合理的命名与分类法。对植物类金属２硫蛋白一级结构进行详细分析后,发现该蛋白两端富含半胱氨酸的区域内关胱氨酸的排列方式颇具规律性,进而提出了以半胱氨酸排列方式为基础的分类及命名法,并阐述了采用这种     

Dof转录因子在植物中的调控作用

DNA binding with one finger(Dof)蛋白是植物中特有的一类转录因子,自1993年在玉米中发现该转录因子到如今已有26年的历史。Dof蛋白只有一个由52个氨基酸组成的单锌指保守结构域,该结构域包含4个保守的半胱氨酸残基和一个二价锌离子,这两者都是Dof转录因子重要的组成部分,二者缺一不可,若半胱氨酸发生突变,或存在其他二价离子螯合剂都将会影响锌指结构的生成,进而使Dof蛋白不能与DNA结合,导致其丧失活性。半胱氨酸残基和Zn2+可以共价结合构成CX2CX21CX2C基序,此基序能够特异识别启动子中的AAAG(或CTTT)序列,从而激活或抑制靶基因的表达。Dof蛋白C-末端氨基酸序列的多变性导致该转录因子进化的多样性,从而在植物的生长发育过程中发挥着不同且重要的功能,如种子萌发、维管的发育和叶片极性、花和花粉发育、光周期反应、参与碳和氮的代谢、合成次生代谢产物、植物的逆境响应过程等。围绕着Dof转录因子的结构、系统进化关系、motif的组成和在植物中发挥的功能展开综述,以期为后续Dof转录因子的研究奠定相应的理论基础。     

植物伸展蛋白的研究进展

伸展蛋白是高等植物细胞壁中一族富含羟脯氨酸的糖蛋白,在植物细胞壁中发挥着重要的生理功能。综述了近几十年对伸展蛋白结构、功能、基因家族以及生物合成与基因表达调节的研究进展。     

PRGL: A cell wall proline-rich protein containning GASA domain in Gerbera hybrida

PRPs (proline-rich proteins) are a group of cell wall proteins characterized by their proline and hy- droproline-rich repetitive peptides. The expression of PRPs in plants is stimulated by wounding and environmental stress. GASA (gibberellic acid stimulated in Arabidopsis) proteins are small peptides sharing a 60 amino acid conserved C-terminal domain containing twelve invariant cysteine residues. Most of GASAs reported are localized to apoplasm or cell wall and their expression was regulated by gibberellins (GAs). It has been reported that, in French bean, these two proteins encoding by two distinct genes formed a two-component chitin-receptor involved in plant-pathogen interactions when plant was infected. We cloned a full-length cDNA of PRGL (proline-rich GASA-like) gene which encodes a protein containing both PRP and GASA-like domains. It is demonstrated that PRGL is a new protein with characteristics of PRP and GASA by analyzing its protein structure and gene expression.     

Enhanced tolerance to heat stress in transgenic plants expressing the GASA4 gene.

We conducted a genetic yeast screen to identify Thermo-tolerance genes (TTOs) in maize kernel cDNA library. During the screening, we identified a maize clone (TTO6) that seemed to confer elevated heat tolerance in comparison to control cells. TTO6 cDNA (GenBank accession no. AY103785) encodes an 11-kDa protein which is 69% similarity to the Arabidopsis GASA4 gene. To further examine heat tolerance in Arabidopsis, we functionally characterized the GASA4 gene and found that heat induced GASA4 expression. Constitutive expression of GASA4 in Arabidopsis led to elevated heat tolerance in transgenic lines. Interestingly, endoplasmic reticulum chaperone expression analysis suggests that GASA4 influences BiP gene expression during heat stress.     

Snakin/GASA proteins: Involvement in hormone crosstalk and redox homeostasis

Snakin/GASA proteins are widely distributed among plant species. They are expressed in different plant organs with high tissue and temporal specificity, and their subcellular localization varies among the different members. Interestingly, all of them maintain 12 cysteines of the C-terminus in highly conserved positions of the aminoacid sequences that are essential for their biochemical activity and probably responsible for their protein structure. Despite their common features, their functions are not completely elucidated and little is known about their mode of action. This review focuses on the current knowledge about this intriguing family of peptides and advances comprising gene regulation analyses, expression pattern studies and phenotypic characterization of mutants and transgenic plants. Furthermore, we discuss the roles of Snakin/GASA proteins in several aspects of plant development, plant responses to biotic or abiotic stress and their participation in hormone crosstalk and redox homeostasis.     

Overexpression of GASA5 increases the sensitivity of Arabidopsis to heat stress

Basal thermotolerance is very important for plant growth and development when plants are subjected to heat stress. However, little is known about the functional mechanism of gibberellins (GAs) in the basal thermotolerance of plants. In the present work, we provide molecular evidence that a member of the gene family encoding the GA-stimulated Arabidopsis (GASA) peptides, namely GASA5, is involved in the regulation of seedling thermotolerance. The GASA5-overexpressing plants displayed a weak thermotolerance, with a faster cotyledon-yellowing rate, lower seedling-survival rate, and slower hypocotyl elongation, in comparison to the wild-type and GASA5 null-mutant (gasa5-1) plants, after heat-stress treatment. The short-hypocotyl phenotype of GASA5-overexpressing plants could be rescued by the exogenous application of salicylic acid (SA), the hormone found to protect plants from heat stress-induced damage. GASA5 expression was inhibited by heat stress but unaffected by the application of exogenous SA. However, expression of the gene encoding the noexpresser of PR genes 1 (NPR1), a key component of the SA-signaling pathway, was downregulated by GASA5 overexpression. Importantly, when different GASA5-genotype plants were treated with heat stress, several genes encoding heat-shock proteins, including HSP101, HSP70B, HSP90.1, HSP17.6-C1, and HSP60, were inhibited by GASA5 overexpression. Meanwhile, hydrogen peroxide was accumulated at high levels in heat stress-treated GASA5-overexpressing plants. These results suggest that the Arabidopsis GASA5 gene acts as a negative regulator in thermotolerance by regulating both SA signaling and heat shock-protein accumulation.     

GASA4, one of the 14-member Arabidopsis GASA family of small polypeptides, regulates flowering and seed development

Members of the plant-specific gibberellic acid-stimulated Arabidopsis (GASA) gene family play roles in hormone response, defense and development. We have identified six new Arabidopsis GASA genes, bringing the total number of family members to 14. Here we show that these genes all encode small polypeptides that share the common structural features of an N-terminal putative signal sequence, a highly divergent intermediate region and a conserved 60 amino acid C-terminal domain containing 12 conserved cysteine residues. Analysis of promoter::GUS (beta-glucuronidase) transgenic plants representing six different GASA loci reveals that the promoters are activated in a variety of stage- and tissue-specific patterns during development, indicating that the GASA genes are involved in diverse processes. Characterization of GASA4 shows that the promoter is active in the shoot apex region, developing flowers and developing embryos. Phenotypic analyses of GASA4 loss-of-function and gain-of-function lines indicate that GASA4 regulates floral meristem identity and also positively affects both seed size and total seed yield.     

Fusion genetic analysis of gibberellin signaling mutants

A fusion genetic strategy was used to identify gibberellin (GA) signaling mutants in transgenic Arabidopsis expressing the beta-glucuronidase (GUS) and firefly luciferase (LUC) reporter genes under control of the GA-responsive GASA1 promoter. Initial analyses determined the spatial and temporal patterns of reporter expression, and showed that reporter induction by GA was antagonized by ABA. gamma-Irradiated M2 progeny with altered reporter activities were identified by LUC bioimaging followed by GUS assays and northern hybridization of the endogenous GASA1 mRNA. Genetic analysis showed that three mutants, which overexpressed both reporters and endogenous GASA1, were caused by recessive (goe1 and goe2, for GASA over-expressed) and semi-dominant (goe3) mutations at different loci. These mutants are altered in their sensitivity to GA and the GA biosynthetic inhibitor paclobutrazol, and in the expression of several GA signaling related genes.