BTB蛋白泛素化介导植物发育和逆境应答的研究进展

BTB (broad-complex, tramtrack, and bric-à-brac)结构域是在真核生物中发现的高度保守的蛋白质相互作用基序。含有BTB结构域的一类蛋白统称为BTB蛋白,它们广泛参与转录调控、蛋白质降解等过程。越来越多的研究表明,该基因在植物生长发育、生物与非生物胁迫等生理过程中具有重要的作用。本文以蛋白结构域为基础,系统总结了该基因家族蛋白在泛素化介导植物发育和逆境应答等过程中的研究进展,为植物中该类基因的研究提供了参考。     

蛋白质SUMO化修饰研究进展

SUMO(small ubiquitin-related modifier)是类泛素蛋白家族的重要成员之一,可与多种蛋白结合发挥相应的功能,其分子结构及SUMO化反应途径都与泛素类似,但二者功能完全不同。SUMO化修饰可参与转录调节、核转运、维持基因组完整性及信号转导等多种细胞内活动,是一种重要的多功能的蛋白质翻译后修饰方式。SUMO化修饰功能的失调可能导致某些疾病的发生。     

类泛素蛋白--SUMO

SUMO(small ubiquitin-related modifier)是泛素(ubiquitin)类蛋白家族的重要成员之一。尽管SUMO的生化反应途径与泛素相似,但不像泛素那样诱导底物蛋白降解。SUMO化能够使蛋白质更加稳定,进而调节许多关键的细胞活动。现从分类、结构、生化途径和生物学功能等方面介绍SUMO及SUMO化过程。     

泛素化在TRAF2介导的NF-κB信号通路中的作用

NF-κB（核因子κ增强子结合蛋白）是核转录因子家族成员,具有调节免疫、炎症和细胞存活的功能.它可被TRAF2（tumor necrosis factor receptor associated factor 2,肿瘤坏死因子受体相关因子2）等相关因子活化.TRAF2包含了N-端的环指结构域和C-端的高度保守结构域.它通过与肿瘤坏死因子受体超家族成员相互作用,介导了下游信号通路.而TRAF2的泛素化在过程中是关键的,鞘磷脂作为TRAF2的泛素化连接酶辅助因子,在TRAF2介导的NF-κB信号通路中发挥重要作用.     

BTB家族蛋白结构与功能的研究进展

BTB(BR-C,ttk,and bab)家族是类Kuppel锌指蛋白家族中的一种,广泛存在于从酵母到人类的各种物种中,它最主要的特征是在N端至少含有一个BTB结构域.BTB结构域是在进化上高度保守的结构域,约含有115个氨基酸.越来越多的研究表明BTB蛋白在转录和调控的过程中起着重要的作用.     

E3连接酶RNF148泛素化降解TSPAN15

真核生物蛋白的泛素化是细胞维持对某些受组成型调节和环境刺激产生的蛋白质水平的基本调节方式,泛素-蛋白酶体途径对蛋白质降解、运输和免疫反应过程的控制等细胞功能起着非常重要的作用．本研究揭示了一个功能未知、具有RING结构特征的Ⅰ型穿膜蛋白RNF148的泛素化降解功能．通过流式筛选、免疫共沉淀、浓度梯度依赖降解实验及泛素化检测等实验证明：RNF148与四跨膜区蛋白(tetraspanin)家族的一个成员TSPAN15有相互作用,即RNF148可以泛素化并降解TSPAN15．RNF148的RING结构被突变后,TSPAN15的泛素化被严重影响;而TSPAN15的N端胞浆段的21位赖氨酸和C端278位赖氨酸被突变为精氨酸后,RNF148对其泛素化的程度也降低．TSPAN15经由RNF148泛素化后会连接 K29位或K63位多泛素链,进而导致TSPAN15的转位或降解．本研究证明RNF148作为泛素连接酶可以泛素化降解TSPAN15．     

SCF(Skp1-Cul1-F-box蛋白)复合物及其在细胞周期中的作用

泛素 -蛋白酶体降解途径在多种蛋白浓度的调节中发挥重要作用。泛素连接酶家族的一个成员SCF复合物 (Skp1- Cul1- F -box蛋白 )通过降解多个细胞周期调节蛋白促使细胞进入增殖周期。本文综述了SCF复合物的组成和结构以及这一复合物对细胞周期调控因子的调节作用。     

LIM蛋白家族的研究进展

LIM蛋白是分子结构中含有一个或多个LIM结构域的蛋白质家族,该家族中的蛋白质通过其LIM结构域与某些结构蛋白,激酶,转录调控因子等多种蛋白质相互作用,对某些基因的表达,细胞分化与发育,细胞骨架形成等发挥重要调控作用。本文介绍LIM蛋白家族的分类与功能,LIM蛋白及其与其他蛋白之间的相互作用,以及LIM蛋白在心血管系统中的作用。     

大豆UBC基因家族鉴定及GmUBC46基因的功能初步分析

泛素/26S蛋白酶体途径在植物响应非生物胁迫反应中起着重要的作用。E2(泛素结合酶,UBC)是蛋白质泛素化中重要的泛素结合酶,与E1和E3共同参与蛋白降解途径。本研究通过构建隐马尔可夫模型,鉴定了54个大豆UBC基因,通过进化树分析将该家族成员分为11个亚家族(A-K)。蛋白保守结构域分析表明,GmUBC家族蛋白成员大部分含有保守Motif 1、Motif 2与Motif 3,且均属于泛素结合酶保守结构域。组织定位分析表明大部分GmUBC家族基因成员在大豆根、茎、叶、花等组织中有所表达。转录组数据表明有20个GmUBC基因在干旱、盐或冷胁迫下具有不同的表达模式,启动子顺式作用元件分析发现其胁迫响应过程可能与激素信号转导相关。进一步通过qRT-PCR发现GmUBC46基因能积极响应干旱、盐或冷胁迫诱导上调表达。通过酵母功能验证表明,GmUBC46基因降低了对干旱或盐胁迫的耐受性。综上,本研究初步阐明了大豆UBC基因家族的基本特性及GmUBC46基因的耐逆功能,为后续研究提供了重要依据和参考价值。     

泛素连接酶E3

蛋白质的泛素化修饰具有高度的特异性,它参与调节细胞内许多的生理活动。蛋白质的泛素化修饰涉及一系列的酶参与反应,包括泛素激活酶E1、结合酶E2以及连接酶E3。而其中泛素连接酶E3对靶蛋白的特异性识别起关键作用。泛素连接酶E3主要由HECT结构域家族、RING结构域家族和U-box结构域家族组成。现对泛素连接酶E3的分类、结构及其对靶蛋白的识别机制等进行综述。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.