菜豆ANK基因家族鉴定及ANK25的表达模式分析

锚蛋白重复序列模体是生物体内最普遍的蛋白质序列模体之一,在多种细胞活动中主要介导蛋白质-蛋白质的相互作用。本研究利用菜豆基因组数据库,通过生物信息学手段对菜豆ANK家族成员及分子生物学特性进行了鉴定。结果显示,菜豆基因组中含有30个ANK家族基因,分布于9条染色体上,其中第5条染色体上含有的ANK基因最多,包含13个基因。蛋白结构域分析发现,ANK25除了含有ANK结构域外还含有RING结构域。亚细胞定位结果显示,ANK25主要分布在细胞膜上。表达模式分析发现,ANK25对干旱、盐和ABA胁迫有响应。本研究为进一步研究菜豆ANK的分类及功能提供了有利的依据。     

牦牛MT-Ⅰ/-Ⅱ cDNA分子克隆及其蛋白质结构分析

利用基因特异引物Y_MTSP₁和Y_MTSP₂,通过RT-PCR从牦牛肝脏组织RNA中克隆出了牦牛MT-Ⅰ(GenbankAccessionNo:AY513744)和MT-Ⅱ(GenbankAccessionNo:AY513745)基因编码区全长。将牦牛MT-Ⅰ和MT-ⅡcDNA序列在CBI上进行同源性搜索发现,牦牛MT-Ⅰ/-Ⅱ编码区序列在不同哺乳动物中相当保守。牦牛MT-Ⅰ和MT-Ⅱ编码的MT-Ⅰ和MT-Ⅱ蛋白分别由61个氨基酸组成,其具有保守的短肽结构如:C-X-C,C-C-X-C-C,C-X-X-C等,其决定MT蛋白分子的整个三维结构,在分子进化上十分保守。同时对牦牛MT的疏水性和跨膜区分析表明,牦牛MT蛋白可能不存在跨膜区,也不存在信号肽,是1种非分泌蛋白。并通过同源比较模建,预测和构建了牦牛MT-Ⅰ和MT-Ⅱ蛋白的分子空间结构,表明牦牛MT-Ⅰ和MT-Ⅱ由α-和β-两个结构域组成,在α-结构域含有5个Cys短肽结构,β-结构域有4个Cys短肽结构,且2个结构域由保守的三肽序列KKS相连。     

多聚谷氨酰胺延伸蛋白募集细胞内正常蛋白质或RNA的分子机制

多聚谷氨酰胺(PolyQ)疾病,是一类由编码蛋白质的基因中CAG三核苷酸重复序列的异常延伸所引发的神经退行性疾病.CAG三核苷酸重复序列导致所编码蛋白质的PolyQ序列的异常延伸,使蛋白质发生错误折叠和积聚,并在细胞内形成包涵体.包涵体的形成是神经退行性疾病的一个重要特征.PolyQ蛋白在积聚过程中,可以将细胞内与其特异相互作用的蛋白质或RNA募集到包涵体中.被募集的其他蛋白质或RNA不仅自身的可溶性组分减少,而且由于被"挟持"到包涵体中其在细胞内的有效组分也相应地减少,从而影响其正常的生物功能.根据特异相互作用的模式,我们将募集作用分为以下几种类型:蛋白质(含Poly Q蛋白)的共积聚;特定结构域或模体介导的募集作用(包括泛素等修饰介导的募集作用);RNA介导的募集作用;以及对分子伴侣蛋白的募集作用.PolyQ延伸蛋白的积聚和对其他组分的募集可能是引发细胞毒性和神经退行性病变的重要原因.     

PH结构域的结构和功能研究进展

PH结构域是一种存在于多种信号转导蛋白和细胞骨架蛋白中的大约由120个氨基酸组成的功能性区域.不同蛋白质中的PH结构域在一级结构上的同源性并不很高,但其空间结构中肽链主链的折叠方式基本相同,而主要差别存在于其中的三个可变环上,含有这些环的侧面带有正电荷,被认为可能是其配体的结合部位.目前已知的配体有G蛋白βγ亚单位（Gβγ）、蛋白激酶C（PKC）和磷脂酰肌醇衍生物（PIP₂或IP₃）,所以PH 结构域可能介导信号蛋白与这些分子间的相互作用,参与细胞信号转导网络的构成.     

p53蛋白质C端的三维结构及生物功能区

利用p53 C端118个氨基酸的mRNA二级结构和Chou-Fasman蛋白质二级结构预测原则,预测p53蛋白质C端289～325为卷曲肽段,368～393段包括两段螺旋结构: α₁ 368～373, α₂ 381～388.其中三段已知的蛋白质二级结构与此mRNA二级结构单元间有准确的对应关系.与四种以多重序列联配为基础的蛋白质二级结构预测方法（准确率均为73.20%左右）相对照,预测结果基本一致.结合单体聚合区31个氨基酸晶体结构,在SGI INDIGO²工作站上构建了p53 C端108个残基的三维结构.进一步揭示了p53 C端诸多生物功能区之间的空间构象关系.     

人分泌型磷脂酶A2-IIA的功能性动力学特征研究

目的 人分泌型磷脂酶A₂-IIA（secretory phospholipase A₂ group IIA,sPLA₂-IIA）在调节细胞脂质代谢和信号传导中具有重要作用,参与了多种急、慢性炎症反应。研究其动力学和变构与功能的关系具有重要意义。方法 利用弹性网络模型（elastic network model,ENM）、微扰响应扫描（perturbation-response scanning,PRS）和蛋白质结构网络（protein structure network,PSN）方法对来自人sPLA₂-IIA的31个分子的结构动力学和变构效应进行分析,并探索其动力学共性和特异性与功能的关系。结果 结果表明,对酶的催化和结构稳定起关键作用的催化残基和参与二硫键形成的半胱氨酸残基具有低运动性,这是对酶共有功能的要求;而涉及与钙离子或膜结合的5个结构区域具有高运动性,它们体现了酶成员的特异性。另外,高运动性区域在PRS分析中显示出对外界微扰响应的高敏感性,表明其在变构调节中起重要作用,而低敏感性残基则在维持结构稳定方面发挥了重要作用。残基运动相关性分析发现,人sPLA₂分子催化位点周围的强相关运动有利于酶催化功能的发挥。结论 本研究有助于深入理解人sPLA₂-IIA成员分子的动力学及功能性变构机制,可为药物设计和准确设计具有精细调节活性的蛋白质提供指导。     

水稻磷脂氢谷胱甘肽过氧化物酶在蛋白质水平上的组织和诱导表达特征

蛋白质是生命活动的主要承担分子,了解蛋白质在有机体中的时空分布对于正确解析蛋白质的功能十分重要．磷脂氢谷胱甘肽过氧化物酶 (PHGPx) 是目前发现的唯一能够直接还原膜上脂类过氧化物的抗氧化酶,在保护生物膜免受过氧化损伤方面有着重要作用．采用Western blot技术,分析了水稻PHGPx (OsPHGPx) 在水稻不同组织以及多种胁迫条件下的蛋白质表达特征．结果表明,OsPHGPx在成熟水稻植株内主要分布于叶组织中,以旗叶中含量最高,而在水稻幼苗中则在茎及叶组织中均检测到较强的杂交信号．OsPHGPx在幼苗中的表达受到H₂O₂和NaCl的强烈诱导,但植物激素对其表达的影响较弱．H₂O₂和NaCl的诱导效果呈现出时间及剂量的相关性,当用0.5 mmol/L H₂O₂处理12 h或用500 mmol/L NaCl处理24 h,此时OsPHGPx表达量达到最大值．对H₂O₂清除剂二甲基硫脲处理的水稻幼苗,外源H₂O₂的再处理并不能诱导OsPHGPx的表达,而NaCl的诱导效果并不受影响,说明H₂O₂可能并不介导NaCl诱导OsPHGPx的表达．这些结果为进一步研究OsPHGPx在水稻中生物学功能奠定了基础．     

线性短模体：介导蛋白质相互作用的新模块

线性短模体是天然无序蛋白实现生物学功能的重要组件.线性短模体具有柔性结构和短小的序列,可以介导瞬时、可逆的蛋白质相互作用,并在发生相互作用时表现出杂泛性.随着实验技术的更新和预测手段的发展,越来越多的线性短模体被发现和重新定义,例如BH3线性短模体.本文重点总结了线性短模体在结构、生物学功能以及进化等方面的特点.对线性短模体功能的研究将为解析细胞信号转导网络、疾病靶标确认、新药发现等领域带来新的思路.     

运用PDB中的同源信息提高NetTurnP的蛋白质β转角预测精度

β转角作为一种蛋白质二级结构类型在蛋白质折叠、蛋白质稳定性、分子识别等方面具有重要作用．现有的β转角预测方法,没有将PDB等结构数据库中先前存在的同源序列的结构信息映射到待预测的蛋白质序列上．PDB存储的结构已超过70 000,因此对一条新确定的序列,有较大可能性从PDB中找到其同源序列．本文融合PDB中提取的同源结构信息(对每一待测序列,仅使用先于该序列存储于PDB中的同源信息)与NetTurnP预测,提出了一种新的β转角预测方法BTMapping,在经典的BT426数据集和本文构建的数据集EVA937上,以马修斯相关系数表示的预测精度分别为0.56、0.52,而仅使用NetTurnP的为0.50、0.46,以Q_total表示的预测精度分别为81.4%、80.4%,而仅使用NetTurnP的为78.2%、77.3%．结果证实同源结构信息结合先进的β转角预测器如NetTurnP有助于改进β转角识别．BTMapping程序及相关数据集可从http://www.bio530.weebly.com获得．     

江浙蝮蛇毒碱性磷脂酶A2正交晶型Ⅰ——0.25nm分辨率晶体结构

江浙蝮蛇毒碱性磷脂酶A₂ 具有强烈的溶血及抗凝血活性 .运用刚体修正技术获得了正交晶型Ⅰ中分子的精确旋转与平移参数 .采用非晶体学二重对称性制约的最小二乘修正方法在 0 .6～ 0 .2 5nm分辨率范围内进行了结构精化 .最终的晶体学R因子为 2 0 .1 % ,键长、键角与标准值的均方根偏差分别为 0 .0 0 1 3nm和 1 .5 5° .与正交晶型Ⅱ结构比较表明 ,二者除了β -折叠部位与Ca ²⁺结合部位构象存在小的差别外 ,磷脂酶A₂分子主体构象极其相似 .2种晶型由不对称单位中 2个分子形成的二体也是类似的 .但是 ,二体中 1个单体分子的相对取向有 5 .5°的差别 ,提示二体结合面有一定柔性 .晶型Ⅰ二体较晶型Ⅱ二体在晶胞中的堆积更紧密 .     

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.