哺乳动物肽聚糖识别蛋白抗菌作用及其机制的研究进展

哺乳动物肽聚糖识别蛋白(PGRPs)是一类可识别肽聚糖的免疫激活分子,具有抗菌活性.它的抗菌机制与其他抗菌肽明显不同.最新研究发现,哺乳动物PGRPs通过与肽聚糖结合,激活在细菌中识别胞浆外错误折叠蛋白质分子的CssR-CssS或CpxA-CpxR双部件系统,最终导至细菌死亡.文中总结了肽聚糖识别蛋白的抗菌作用及其机制的相关研究进展.     

我国科学家揭示兰州熊蜂肽聚糖识别蛋白的结构与功能

正中国农业科学院蜜蜂研究所蜂种质资源与育种团队揭示了兰州熊蜂肽聚糖识别蛋白的结构与功能。该研究丰富了传粉蜂类先天免疫系统中模式识别受体的认知,为我国本土熊蜂资源保护和利用奠定了基础。该成果在线发表在《国际分子科学杂志》上。     

嗜酸乳杆菌细胞壁肽聚糖的分离提取

分别采用超声波法、溶菌酶法、三氯乙酸法对嗜酸乳杆菌细胞壁肽聚糖进行分离提取.结果表明超声波法的最优组合为超声功率400 W,超声时间30 min,水浴温度40℃,肽聚糖得率10.2%;溶菌酶法的最优组合为溶菌酶添加量4 mg/mL,水浴温度55%,作用时间5 h,pH 7,肽聚糖得率10.0%;三氯乙酸法肽聚糖得率15.8%.通过多重比较,最终确定采用三氯乙酸法提取嗜酸乳杆菌细胞壁肽聚糖.     

黄颡鱼长型肽聚糖识别蛋白(pfPGRP-L)原核表达和多克隆抗体的制备

为进一步研究肽聚糖识别蛋白(peptidoglycan recognition proteins,PGRPs)在先天性免疫应答中的生物学功能,在前期克隆黄颡鱼长型肽聚糖识别蛋白(pfPGRP-L)c DNA全长的基础上,根据pfPGRP-L基因中高亲水性区域序列设计特异性引物扩增出编码序列,将该基因片段克隆到p GEX-4T-1质粒,构建重组表达载体。SDS-PAGE电泳检测该目的蛋白大小约为51 ku,与理论值大小符合,回收蛋白并纯化,与弗氏佐剂等量混合后注射新西兰大白兔制备多克隆抗体,用ELISA和Western blotting分别检测该抗体,结果显示:抗体效价可达1∶256 000,且有特异性条带,表明pfPGRP-L的多克隆抗体制备成功。此外,Western blotting检测黄颡鱼不同组织pfPGRP-L蛋白的表达,发现在鳃、胸腺、肝脏、肾脏、头肾、脾脏、血液和肠道等不同组织中都有目的条带,而在脾脏和肠道中表达更强。为pfPGRP-L的抗菌作用和功能研究奠定基础。     

两歧双歧杆菌完整肽聚糖的质量评价

利用复合酶法提取两歧双歧杆菌细胞壁中的完整肽聚糖(Whole Peptidoglycan,WPG),并对所提取的WPG纯度进行测定。分别制备葡萄糖和蛋白质标准曲线,对总糖含量和蛋白质含量进行测定。总糖含量和蛋白质含量分别为34.36%和47.15%,说明制备出的肽聚糖纯度较高。     

纳豆芽孢杆菌胞壁肽聚糖提取工艺优化及其结构初步鉴定

为探究纳豆芽孢杆菌细胞壁肽聚糖提取工艺及其结构,本实验以纳豆芽孢杆菌为研究材料,采用响应面优化超声波破碎法,提取纳豆芽孢杆菌细胞壁,然后经三氯乙酸、乙酸钠、氯仿、甲醇、胰蛋白酶处理等操作分离得到较为纯净的肽聚糖并对其组成成分和结构进行分析。结果表明:用超声波破碎法提取的纳豆芽孢杆菌细胞壁得率为45.8%,纯化后得到的肽聚糖得率为8.5%。所得纳豆芽孢杆菌胞壁肽聚糖中总糖占39.77%,蛋白质占54.47%,总脂含量占4.5%。溶菌酶溶解实验9 h后眼观变为澄清。经红外光谱(IR)和高效液相分析提取的肽聚糖样本与肽聚糖已知结构特征相一致。经过聚丙烯酰胺凝胶电泳(SDS-PAGE)分析经溶菌酶水解后的肽聚糖分子量约为60 ku。     

Lb.casei.Zhang肽聚糖体内外抗肿瘤作用

为研究干酪乳杆菌Lb.casei.Zhang细胞壁肽聚糖(peptidoglycan;PG)的抗肿瘤作用,用流式细胞仪检测肽聚糖对人胃癌BGC-823细胞生长周期的影响。以肝癌H22细胞移植瘤昆明小鼠为模型,分别采用原位杂交和免疫组化方法检测小鼠移植瘤增殖细胞核抗原(PCNA)mRNA的表达以及凋亡因子Bcl-2和Bax基因的蛋白表达。结果显示,肽聚糖能够阻滞人胃癌BGC-823细胞生长于G0/G1期;实验组PCNA mRNA的表达和Bcl-2基因的蛋白表达平均光密度值均明显低于对照组,而Bax基因蛋白表达情况则相反,与对照组比较,均差异显著(α=0.05),且抑瘤率达37.21%。提示干酪乳杆菌Lb.casei.Zhang细胞壁肽聚糖具有抗肿瘤作用。     

大菱鲆(Scophthalmus maximus L.)tlr3基因的鉴定及其在病原感染前后的表达

Toll样受体(Toll like receptor,TLR)是非常重要的病原体模式识别受体,它通过识别微生物特异性分子模式来控制针对病原体的宿主免疫应答,在先天免疫和获得性免疫中起重要作用.迄今为止,已经在动物中发现脊椎动物TLR的22个主要家族成员.尽管以前的研究已经鉴定了几个大菱鲆的Toll样受体基因(tlr2,...     

活性叶酸、肽聚糖对哺乳期母猪哺育能力的影响

本试验研究了哺乳期母猪日粮中添加活性叶酸和肽聚糖对母猪泌乳力(20日龄窝重)、28日龄断奶窝重、仔猪成活率和腹泻率等的影响,结果表明,哺乳母猪日粮中添加活性叶酸、肽聚糖能显著降低哺乳仔猪腹泻率(P<0.05),并有一定的提高母猪泌乳力,促进仔猪生长、提高成活率作用。     

Toll样受体在家畜繁殖性疾病中的作用

Toll样受体是天然免疫系统中的一种重要模式识别受体,可选择性识别病原微生物而启动天然免疫,在宿主天然免疫和获得性免疫中具有重要作用。此外,大量研究表明,Toll样受体基因的多态性与多种动物的细菌、病毒和寄生虫性疾病密切相关,说明通过Toll样受体基因的研究可为动物分子标记辅助选育研究提供依据。本文就Toll样受体家族的基本情况及其在家畜繁殖病理中的主要作用进行了综述。     

Structure of tracheal cytotoxin in complex with a heterodimeric pattern-recognition receptor

Tracheal cytotoxin (TCT), a naturally occurring fragment of Gram-negative peptidoglycan, is a potent elicitor of innate immune responses in Drosophila. It induces the heterodimerization of its recognition receptors, the peptidoglycan recognition proteins (PGRPs) LCa and LCx, which activates the immune deficiency pathway. The crystal structure at 2.1 angstrom resolution of TCT in complex with the ectodomains of PGRP-LCa and PGRP-LCx shows that TCT is bound to and presented by the LCx ectodomain for recognition by the LCa ectodomain; the latter lacks a canonical peptidoglycan-docking groove conserved in other PGRPs. The interface, revealed in atomic detail, between TCT and the receptor complex highlights the importance of the anhydro-containing disaccharide in bridging the two ectodomains together and the critical role of diaminopimelic acid as the specificity determinant for PGRP interaction.     

几丁质触发植物免疫的研究现状与展望

真菌病害是植物病害中最为严重的一种,世界上70%—80%的植物病害都是由真菌引起。几丁质是病原真菌细胞壁的重要组成成分,是一种典型的病原相关分子模式（pathogen-associated molecular pattern,PAMP）。当植物受到病原真菌入侵,位于细胞膜上的模式识别受体（pattern recognition receptor,PRR）能够直接与几丁质及其寡糖相互作用并触发植物的免疫反应。近几年,随着植物几丁质受体的成功鉴定,其与几丁质的相互作用机制以及几丁质触发植物免疫的分子机理被广泛研究,并取得了许多重要进展。为了较全面、系统地反应几丁质触发免疫研究的历史沿革、研究现状和发展趋势,笔者就植物对几丁质的识别机制、信号转导以及病原真菌对几丁质触发的免疫反应的抑制机制这3方面进行了综述,并对未来研究的发展方向进行了探讨。     

常见病原菌MAMPs在植物天然免疫中的作用

MAMPs又称病原相关分子模式,在植物的抗病性中发挥着重要作用。在充满潜在致病微生物的环境中,植物能够很好地存活下来,主要功劳在于其具有强大的病原体识别体系和快速的免疫应答系统。植物可以从寄生病原菌和非寄生病原菌中识别几种通用的MAMPs。MAMPs对于病原菌微生物来说,经常是序列高度保守且组成结构不可缺少的。在植物中,MAMPs被其相对应的PRRs识别的过程称为微生物或病原菌引起的免疫。主要介绍了几种常见的MAMPs及其在植物天然免疫研究中的作用。     

TLR11 activation of dendritic cells by a protozoan profilin-like protein

Mammalian Toll-like receptors (TLRs) play an important role in the innate recognition of pathogens by dendritic cells (DCs). Although TLRs are clearly involved in the detection of bacteria and viruses, relatively little is known about their function in the innate response to eukaryotic microorganisms. Here we identify a profilin-like molecule from the protozoan parasite Toxoplasma gondii that generates a potent interleukin-12 (IL-12) response in murine DCs that is dependent on myeloid differentiation factor 88. T. gondii profilin activates DCs through TLR11 and is the first chemically defined ligand for this TLR. Moreover, TLR11 is required in vivo for parasite-induced IL-12 production and optimal resistance to infection, thereby establishing a role for the receptor in host recognition of protozoan pathogens.     

Genomic insights into the immune system of the sea urchin

Comparative analysis of the sea urchin genome has broad implications for the primitive state of deuterostome host defense and the genetic underpinnings of immunity in vertebrates. The sea urchin has an unprecedented complexity of innate immune recognition receptors relative to other animal species yet characterized. These receptor genes include a vast repertoire of 222 Toll-like receptors, a superfamily of more than 200 NACHT domain-leucine-rich repeat proteins (similar to nucleotide-binding and oligomerization domain (NOD) and NALP proteins of vertebrates), and a large family of scavenger receptor cysteine-rich proteins. More typical numbers of genes encode other immune recognition factors. Homologs of important immune and hematopoietic regulators, many of which have previously been identified only from chordates, as well as genes that are critical in adaptive immunity of jawed vertebrates, also are present. The findings serve to underscore the dynamic utilization of receptors and the complexity of immune recognition that may be basal for deuterostomes and predicts features of the ancestral bilaterian form.     

Dual activation of the Drosophila toll pathway by two pattern recognition receptors

The Toll-dependent defense against Gram-positive bacterial infections in Drosophila is mediated through the peptidoglycan recognition protein SA (PGRP-SA). A mutation termed osiris disrupts the Gram-negative binding protein 1 (GNBP1) gene and leads to compromised survival of mutant flies after Gram-positive infections, but not after fungal or Gram-negative bacterial challenge. Our results demonstrate that GNBP1 and PGRP-SA can jointly activate the Toll pathway. The potential for a combination of distinct proteins to mediate detection of infectious nonself in the fly will refine the concept of pattern recognition in insects.     

家蚕先天性免疫的研究进展

蚕桑生产是我国的传统优势产业,但蚕病却给养蚕业造成很大的损失。由于产业发展的需要,家蚕的免疫防御机制是人们长期关注的热点。家蚕虽然不具有人类高度专一的获得性免疫,但具有对病原微生物感染作出快速有效应答的先天性免疫系统。家蚕受到微生物的感染后,体内会合成抗菌肽,然后抗菌肽被分泌到血淋巴中去消灭病原体。其中,模式识别受体、免疫信号传导途径以及抗菌肽在体液免疫中起着非常重要的作用。     

Decoding the patterns of self and nonself by the innate immune system

The innate immune system evolved several strategies of self/nonself discrimination that are based on the recognition of molecular patterns demarcating infectious nonself, as well as normal and abnormal self. These patterns are deciphered by receptors that either induce or inhibit an immune response, depending on the meaning of these signals.