Yersinia type Ⅲ effectors perturb host innate immune responses

The innate immune system is the first line of defense against invading pathogens. Innate immune cells recognize molecular patterns from the pathogen and mount a response to resolve the infection. The production of proinflammatory cytokines and reactive oxygen species, phagocytosis, and induced programmed cell death are processes initiated by innate immune cells in order to combat invading pathogens. However, pathogens have evolved various virulence mechanisms to subvert these responses. One strategy utilized by Gram-negative bacterial pathogens is the deployment of a complex machine termed the type Ⅲ secretion system(T3SS). The T3SS is composed of a syringe-like needle structure and the effector proteins that are injected directly into a target host cell to disrupt a cellular response. The three human pathogenic Yersinia spp.(Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis) are Gramnegative bacteria that share in common a 70 kb virulence plasmid which encodes the T3 SS. Translocation of the Yersinia effector proteins(YopE, YopH, YopT, YopM, YpkA/YopO, and YopP/J) into the target host cell results in disruption of the actin cytoskeleton to inhibit phagocytosis, downregulation of proinflammatory cytokine/chemokine production, and induction of cellular apoptosis of the target cell. Over the past 25 years, studies on the Yersinia effector proteins have unveiled tremendous knowledge of how the effectors enhance Yersinia virulence. Recently, the long awaited crystal structure of YpkA has been solved providing further insights into the activation of the YpkA kinase domain. Multisite autophosphorylation by YpkA to activate its kinase domain was also shown and postulated to serve as a mechanism to bypass regulation by host phosphatases. In addition, novel Yersinia effector protein targets, such as caspase-1, and signaling pathways including activation of the inflammasome were identified. In this review, we summarize the recent discoveries made on Yersinia effector proteins and their contribution to Yersinia pathogenesis.

Type-Ⅲ数字补偿器在双Buck逆变器中的实现

开关电源环路设计、补偿与参数整定一直是研究的焦点,本文所研究的典型双Buck逆变器是由2个Buck电路组成的。首先分析电流连续控制模式(CCM)下考虑寄生参数的单Buck电路系统模型,通过分析波特图采用经典的PI控制器无法降低系统静态误差和提高动态响应能力;然后设计了基于零极点补偿的Type-Ⅲ数字补偿器,在MathCad软件下搭建数学模型进行理论分析,并使用双线性变换法实现数字化转换;最后制作实验样机验证控制模型及环路补偿参数的合理性。结果表明,CCM下考虑寄生参数的双Buck逆变器采用所建立的Type-Ⅲ补偿器,具有良好的抗负载扰动性能。

Molecular Cloning and Bioinformatics Analysis of TypeⅢSecretion System Effector Protein HY 322 Gene of Vibrio alginolyticus

In this study,Hy322 gene was cloned from Vibrio alginolyticus.The total length of its gene was 969 bp,and it could encode 322 amino acids.The physicochemical properties,protein structure,genetic evolutionary relationship and antigenic characteristics of the effector protein Hy322 of V.alginolyticus HY9901 type Ⅲ secretion system were studied and analyzed by bioinformatics methods and tools.The results showed that Hy322 is an unstable hydrophilic and acidic protein without a transmembrane region and a signal peptide,and secondary structure to α-helix.The evolutionary analysis showed that V.alginolyticus HY9901 and V.harveyi were clustered together,which indicated that the genetic relationship between the two species was closest.HY322 contains a FliN super family conserved domain associated with Flagellar motor switch.Bioinformatics analysis showed that the B-cell preponderant epitopes of Hy322 might be localized in the regions of 32-33,100-102,138-140,215-216,235-238 and 246-249.The 3D structure model of Hy322 subunit was simulated by SWISS-MODEL software and itwas found that the yscQ of Yersinia were similar and the similarity was 42.25%.In this study,the feasibility of Hy322 as a common antigen of Vibrio was verified from the perspective of bioinformatics,which laid the foundation for the next step in vaccine development.

Robust and intrinsic type-Ⅲnodal points in a diamond-like lattice

An ideal type-Ⅲnodal point is generated by crossing a completely flat band and a dispersive band along a certain momentum direction.To date,the type-Ⅲnodal points found in two-dimensional(2D)materials have been mostly accidental and random rather than ideal cases,and no one mentions what kind of lattice can produce ideal nodal points.Here,we propose that ideal type-Ⅲnodal points can be obtained in a diamond-like lattice.The flat bands in the lattice originate from destructive interference of wavefunctions,and thus are intrinsic and robust.Moreover,the specific lattice can be realized in some 2D carbon networks,such as T-graphene and its derivatives.All the carbon structures possess type-ⅢDirac points.In two of the structures,consisting of triangular carbon rings,the type-ⅢDirac points are located just on the Fermi level and the Fermi surface is very clean.Our research not only opens a door to finding the ideal type-ⅢDirac points,but also provides 2D materials for exploring their physical properties experimentally.

黄单胞菌Ⅲ型分泌系统效应蛋白的研究进展

黄单胞菌借助保守的III型分泌系统,将多个效应蛋白注入植物细胞,克服宿主的防卫,利于黄单胞菌在植物体内发挥毒性功能。最近对III型效应蛋白致病机理开展了大量研究,结果发现具有酶功能的效应蛋白在黄单胞菌及其宿主间的相互作用中发挥非常重要的作用。此外,黄单胞菌存在一类独特的III型效应蛋白(Avr Bs3家族)。迄今为止,仅在黄单胞菌和雷尔氏菌(Ralstonia solanacearum)中发现Avr Bs3家族效应蛋白,Avr Bs3家族通过模拟转录激活子来操纵寄主植物易感基因的表达。

致病菌Ⅲ型分泌系统特有效应蛋白的预测及其特有模体分析

目的对病原菌Ⅲ型分泌系统(TTSS)效应蛋白在非致病菌中进行直系同源基因预测,以获得病原菌Ⅲ型分泌系统特有效应蛋白,并进一步对特有效应蛋白模体构成进行分析,旨在更深入地认识TTSS效应蛋白,为理论研究和生物学实验提供参考。方法利用彼此最佳blast方法对效应蛋白在构建的非致病性细菌蛋白质数据库中进行直系同源基因预测,并利用Inter Pro Scan对预测获得的特有效应蛋白序列进行模体搜索分析。结果在49个收集整理的致病菌Ⅲ型分泌系统效应蛋白序列中,有18个效应蛋白在非致病菌中存在直系同源基因,31个效应蛋白(即TTSS特有效应蛋白)在非致病菌中没有直系同源基因;对31个Ⅲ型分泌系统特有效应蛋白序列进行模体分析,获得了12个效应蛋白特有模体。结论 31个致病菌Ⅲ型分泌系统特有效应蛋白序列的获得,为更精确地在致病性细菌基因组内预测获得新的效应蛋白序列奠定了基础;12个效应蛋白特有模体的获得及其基因本体注释分析进一步理解了效应蛋白的作用机制。

肠出血性大肠杆菌Ⅲ型分泌系统效应因子与宿主细胞相互作用研究进展

肠出血性大肠杆菌(Enterohemorrhagic Escherichia coli,EHEC)通过其Ⅲ型分泌系统将效应因子注入到宿主细胞内,破坏宿主细胞内的多种信号通路从而有利于细菌的感染及定植。近年来对于EHEC Ⅲ型分泌系统效应因子与宿主细胞相互作用研究成为EHEC致病机制研究新的热点,研究表明,除了经典的效应因子外,一些新发现的效应因子在细菌的致病过程中也发挥着重要作用,有些效应因子能够抑制宿主细胞内正常的信号通路,有些效应因子还具有抑制细胞凋亡,干扰炎症信号通路和抑制吞噬的作用。这些发现揭示了EHEC效应因子具有多种功能,它们通过与宿主细胞间的相互作用,在细菌的感染过程中发挥着重要作用。

黄单胞杆菌Ⅲ型效应子研究进展

许多黄单胞杆菌通过Ⅲ型分泌系统将效应子注入到寄主细胞中,引起寄主的免疫反应或感病。最近的研究提供了大量的关于Ⅲ型效应子作为致病因子或激发子同寄主互作的实验数据。笔者综述了黄单胞杆菌Ⅲ型效应子的分类及avrbs3、AvrRxv/YopJ、XopN、XopD家族的主要功能,重点介绍了Ⅲ型效应子的酶活性功能在同寄主互作过程中发挥的重要作用,如XopD的SUMO化作用;AvrBs3家族效应子在调节寄主基因转录方面的作用;XopN抑制PAMP介导的植物免疫反应的功能等。论文还对一些研究深入的Ⅲ型效应子及其与寄主的互作进行了比较详细的评述,讨论Ⅲ型效应子的研究对于植物抗病基因工程的影响及重要意义,并对Ⅲ型效应子的研究方向进行了展望。

植物病原细菌Ⅲ型效应子的双向作用

病原细菌Ⅲ型效应子对寄主植物防卫反应的抑制和诱导决定了互作中植物抗(感)病性状。本文概述了植物病原菌Ⅲ型效应子抑制和诱导寄主植物防卫反应的双向作用,所涉及的抑制和诱导作用主要包括植物过敏反应、植物细胞壁介导的防卫反应以及植物抗病信号介导的抗性反应等。本文还对植物病原菌Ⅲ型效应子双向作用的研究和应用进行了展望。

一个新的体外快速鉴定十字花科黑腐病菌Ⅲ型效应物的报告质粒的构建

植物病原菌侵染寄主的过程就是病原菌和寄主植物相互作用的过程。在这个相互作用过程中,Ⅲ型分泌系统和Ⅲ效应物与病原菌致病密切相关。大部分革兰氏阴性植物病原菌通过Ⅲ型分泌系统定向的把效应物蛋白传递到宿主细胞,效应物蛋白进入植物体引起致病或过敏反应。本研究将百日咳杆菌的腺苷酸环化酶基因连接至含启动子的pLAFRJ载体上,从而构建出一个新的体外快速鉴定Ⅲ型效应物的报告质粒pJ-JA,并用已鉴定为Ⅲ型效应物基因的十字花科黑腐病菌XC1553的启动子和信号区验证该报告质粒,证明这个系统是可以工作的。该报告质粒为进一步精确筛选鉴定十字花科黑腐病菌Ⅲ型效应物提供了材料。

嗜水气单胞菌Ⅲ型分泌系统研究进展

主要对嗜水气单胞菌Ⅲ型分泌系统、效应蛋白及其致病机理等方面的研究进展进行了综述。细菌分泌系统的发现是近年来细菌致病机制研究的重要进展,许多革兰氏阴性细菌借助于细菌的分泌系统,分泌出毒性因子和效应蛋白,与寄主进行分子交流。

沙门氏菌Ⅲ型分泌候选基因yiiG的比较基因组分析

目的研究沙门氏菌Ⅲ型分泌候选基因yiiG的分布和进化。方法利用序列比对检测yiiG分布,通过比较基因组学和进化树重建分析基因进化史。结合RNA-seq数据,分析yiiG和其他沙门氏菌毒性基因表达相关性。生物信息预测Yii G蛋白是否含有公认的Ⅲ型分泌系统(T3SS)分泌信号。结果 yiiG在S.enterica种内enterica亚种高度保守,在其他亚种多变;S.bongori种内无分布。在沙门氏菌外其他菌属中,仅在部分志贺氏菌和大肠杆菌中有yiiG分布。所有yiiG所在基因组近邻区域位置保守。S.enterica种内enterica亚种的大量血清型中,yiiG基因上游存在一个head-to-head排列的高同源未注释基因(yiiGRrc)。RNA-seq数据分析揭示yiiG在细菌侵染环境刺激下表达、表达水平和T3SS相关毒性基因高度相关。各种新效应蛋白预测软件分析提示Yii G具有T3SS分泌/转运信号。结论 yiiG基因座为一个古老、遗传重组活跃的热点区域;yiiG与沙门氏菌毒性高度相关;另外,新鉴定的yiiG密切相关基因yiiGRrc,为进一步理解yiiG基因家族及其功能分化研究奠定基础。

沙眼衣原体Ⅲ型分泌系统效应蛋白研究进展

沙眼衣原体(Chlamydia trachomatis,Ct)是专性细胞内致病菌,主要通过Ⅲ型分泌系统(type Ⅲ secretion system,T3SS)直接将效应蛋白分泌到宿主细胞。T3SS效应蛋白在Ct发育以及与宿主细胞相互作用中发挥重要作用,如调节宿主细胞肌动蛋白骨架、破坏免疫信号通路以及控制宿主细胞凋亡等。本文综述了沙眼衣原体T3SS效应蛋白最新研究进展。

水稻白叶枯病菌Ⅲ型效应物基因hpaF与毒力相关

【目的】稻黄单胞杆菌水稻致病变种Xanthomonas oryzae pv.oryzae(Xoo)PXO99A菌株中PXO_03420基因被注释为编码具有多个LRR的Ⅲ型效应物基因hpaF,本研究旨在明确hpaF基因的功能,为完善XooⅢ型效应物的研究提供一定的理论基础.【方法】通过同源双交换构建hpaF基因的缺失突变体,并通过表型分析、致病性试验和遗传互补对该基因的功能进行研究.【结果和结论】本研究发现,hpaF基因突变后对水稻日本晴品种的致病力降低了51.81%,减弱了细菌在非寄主植物蓖麻上的过敏反应.而带有hpaF全基因片段的pLAFR3能够恢复hpaF突变体的致病表型,结果表明hpaF基因与水稻白叶枯病菌的致病性相关.

细菌Ⅲ型分泌系统及其效应蛋白致病性研究进展

细菌Ⅲ型分泌系统(T3SS)是细菌分泌毒力因子的重要分泌系统之一,也是抗菌药物抑制细菌繁殖生长的有效靶标。细菌Ⅲ型分泌系统是革兰阴性菌不断进化而来的毒力决定簇之一,是细菌在长期进化中逐渐形成的入侵宿主细胞的特异性机制。近几年对T3SS结构、装配和致病作用的深入研究取得重大的突破。细菌Ⅲ型分泌系统的致病机制和蛋白细胞结构装置对疾病的预防和控制有着重要的意义。

铜绿假单胞菌Ⅲ型分泌系统效应蛋白的作用及机制研究进展

铜绿假单胞菌(PA)是一种引起院内感染的革兰阴性病原菌,PA可通过Ⅲ型分泌系统(T3SS)将效应蛋白转入宿主细胞内而引起急性感染,并在效应蛋白的作用下逃避吞噬细胞的吞噬作用。因此,明确T3SS及其效应蛋白的激活、调控机制有助于为PA的治疗提供新的思路。本文对T3SS的组成和功能、效应蛋白的分泌方式及作用机制进行综述,旨在为新型抗菌药物的研发提供理论基础。

Diverse interactions of five core type Ⅲ effectors from Ralstonia solanacearum with plants

Ralstonia solanacearum is a widespread plant bacterial pathogen that can launch a range of type Ⅲ effectors(T3Es)to cause disease.In this study,we isolate a pathogenic R.solanacearum strain named P380 from tomato rhizosphere.Five out of 12 core T3Es of strain P380 are introduced into Pseudomonas syringae DC3000D36E separately to determine their functions in interacting with plants.DC3000D36E that harbors each effector suppresses FliC-triggered Pti5 and ACRE31 expression,ROS burst,and callose deposition.RipAE,RipU,and RipW elicit cell death as well as upregulate the MAPK cascades in Nicotiana benthamiana.The derivatives RipC1^(△DDXDX(T/V))and RipW^(△DDKXXQ)but not RipAE^(K310R) fail to suppress ROS burst.Moreover,RipAE^(K310R) and RipW^(△DDKXXQ) retain the cell death elicitation ability.RipAE and RipW are associated with salicylic acid and jasmonic acid pathways,respectively.RipAE and RipAQ significantly promote the propagation of DC3000D36E in plants.The five core T3Es localize in diverse subcellular organelles of nucleus,plasma membrane,endoplasmic reticulum,and Golgi network.The suppressor of G2 allele of Skp1 is required for RipAE but not RipU-triggered cell death in N.benthamiana.These results indicate that the core T3Es in R.solanacearum play diverse roles in plantpathogen interactions.

联合H.264和多码率Turbo码的无线视频传输

提出了一种无线视频流联合信源信道编码传输的具体方案,结合H.264视频编码,对其进行合理数据分割后采用UEP技术,并联合信道设计了一个支持信道UEP的多码率Turbo编解码器,同时把Turbo编码与type-Ⅲ HARQ混合自动重传请求机制结合以达到更可靠的数据传输保证。通过仿真实验证明,这种设计方法可进一步优化系统在恶劣的无线信道下的链路吞吐量和取得更好的视频重建质量。

The Xanthomonas typeⅢeffector Xop AP prevents stomatal closure by interfering with vacuolar acidification

Plant stomata close rapidly in response to a rise in the plant hormone abscisic acid(ABA)or salicylic acid(SA)and after recognition of pathogenassociated molecular patterns(PAMPs).Stomatal closure is the result of vacuolar convolution,ion efflux,and changes in turgor pressure in guard cells.Phytopathogenic bacteria secrete typeⅢeffectors(T3Es)that interfere with plant defense mechanisms,causing severe plant disease symptoms.Here,we show that the virulence and infection of Xanthomonas oryzae pv.oryzicola(Xoc),which is the causal agent of rice bacterial leaf streak disease,drastically increased in transgenic rice(Oryza sativa L.)plants overexpressing the Xoc T3E gene Xop AP,which encodes a protein annotated as a lipase.We discovered that Xop AP binds to phosphatidylinositol 3,5-bisphosphate(Ptd Ins(3,5)P_(2)),a memb rane phospholipid that functions in p H control in lysosomes,membrane dynamics,and protein trafficking.Xop AP inhibited the acidification of vacuoles by competing with vacuolar H^(+)-pyrophosphatase(V-PPase)for binding to Ptd Ins(3,5)P_(2),leading to stomatal opening.Transgenic rice overexpressing Xop AP also showed inhibition of stomatal closure when challenged by Xoc infection and treatment with the PAMP flg22.Moreover,Xop AP suppressed flg22-induced gene expression,reactive oxygen species burst and callose deposition in host plants,demonstrating that Xop AP subverts PAMP-triggered immunity during Xoc infection.Taken together,these findings demonstrate that Xop AP overcomes stomatal immunity in plants by binding to lipids.

Characterization of chromosome segment substitution lines reveals candidate genes associated with the nodule number in soybean

Soybean is one of the most important food crops worldwide.Like other legumes,soybean can form symbiotic relationships with Rhizobium species.Nitrogen fixation of soybean via its symbiosis with Rhizobium is pivotal for sustainable agriculture.Type Ⅲ effectors(T3Es)are essential regulators of the establishment of the symbiosis,and nodule number is a feature of nitrogen-affected nodulation.However,genes encoding T3Es at quantitative trait loci(QTLs)related to nodulation have rarely been identified.Chromosome segment substitution lines(CSSLs)have a common genetic background but only a few loci with heterogeneous genetic information;thus,they are suitable materials for identifying candidate genes at a target locus.In this study,a CSSL population was used to identify the QTLs related to nodule number in soybean.Single nucleotide polymorphism(SNP)markers and candidate genes within the QTLs interval were detected,and it was determined which genes showed differential expression between isolines.Four candidate genes(GmCDPK28,GmNAC1,GmbHLH,and GmERF5)linked to the SNPs were identified as being related to nodule traits and pivotal processes and pathways involved in symbiosis establishment.A candidate gene(GmERF5)encoding a transcription factor that may interact directly with the T3E NopAA was identified.The confirmed CSSLs with important segments and candidate genes identified in this study are valuable resources for further studies on the genetic network and T3Es involved in the signaling pathway that is essential for symbiosis establishment.