大型真菌免疫调节蛋白的研究进展

真菌免疫调节蛋白是一类具有抑菌、抗肿瘤和免疫调节等生物学功能的小分子蛋白质。概述真菌免疫调节蛋白的序列特性、空间结构、生物学功能及调控机理等研究进展,并对其研发的发展趋势进行展望。     

真菌免疫调节蛋白基因LZ-8过表达载体的构建及转化灵芝原生质体的研究

灵芝Ganoderma lingzhi是我国著名的药用真菌。但是,作为一种营养和保健价值都非常高的大型担子菌,灵芝还缺乏完善的转基因方法和安全转基因体系。本研究建立了免疫调节蛋白基因的过表达系统,并利用真菌特异性启动子GPD、终止子NOS和目的基因LZ-8构建真菌特异性双T-DNA表达载体p SB130NG-LZ8;利用溶壁酶提取灵芝原生质体,并用FDA染色法检测灵芝原生质体活性,原生质体成活率约为80%。通过PEG转化法对灵芝原生质体成功进行了转化,转化得到的原生质体在带有潮霉素抗性平板上长出,转化率为3–4/μgpSB130NG-LZ8+107个原生质体。转化子通过PCR检测和荧光定量PCR检测,获得LZ-8在灵芝中的过表达。     

紫芝免疫调节蛋白基因的原核表达与功能分析

以紫芝(Ganodermasinense)真菌免疫调节蛋白基因(FIP-gsi)为材料,采用原核表达技术进行蛋白表达,利用基质辅助激光解吸附质谱技术(MALDI-MS)鉴定表达的蛋白,通过体外诱导细胞因子表达技术分析细胞因子基因的表达模式,为真菌免疫调节蛋白生物活性及作用机制的研究奠定基础。结果表明:紫芝真菌免疫调节蛋白基因(FIP-gsi)可在原核细胞中表达,表达出的重组蛋白FIP-gsi约占大肠杆菌总蛋白的46.1%;基质辅助激光解吸附质谱技术鉴定显示表达的蛋白为FIP-gsi,与灵芝(G.lucidum)真菌免疫调节蛋白LZ-8有88.6%的一致性;重组蛋白FIP-gsi能够诱导细胞因子IL(interleukin)-2、IL-4、IFN(interferon)-γ,TNF(tumor necrosis factor)-α,LT(lymphotoxin)及IL-2 R(IL-2 receptor)表达,并且呈现一定的剂量关系。     

氨基酸定点突变提高灵芝蛋白LZ-8热稳定性的研究

通过氨基酸定点突变技术提高灵芝免疫调节蛋白LZ-8的热稳定性。通过分子动力学模拟结合温度因子预测对LZ-8氨基酸突变位点进行理性设计,在毕赤酵母X33菌株内构建并表达LZ-8突变体蛋白,采用HeLa细胞生长抑制实验和差示量热扫描分析检测并比较了LZ-8突变前后生物学活性及热力学参数。结果显示,LZ-8 N-端α螺旋为理论预测的温度敏感区域,在该区域进行F8W和R9K氨基酸双位点突变,突变后的LZ-8热稳定性提高,相变温度Tm上升0.92℃,相转变焓值ΔH提高23.14 kJ/mol,但突变后LZ-8生物学活性基本不变,LZ-8和LZ-8突变体对HeLa细胞生长抑制的IC50值分别是2.238μg/mL和2.407μg/mL。通过理性设计氨基酸突变位点,获得了稳定性提高但生物学活性不变的灵芝免疫调节蛋白LZ-8的突变体。     

辣椒疫霉PcCRN20-C蛋白的表达纯化及结晶 *

CRN(crinkling and necrosis-inducing protein)为疫霉菌在与寄主互作过程中分泌的一类特有胞质效应因子,干扰寄主细胞正常的生理代谢和功能。采用PCR法从辣椒疫霉LT1534菌株cDNA中克隆PcCRN20-C基因。该基因序列长783bp,编码261个氨基酸。构建重组表达载体,并转化大肠杆菌BL21(DE3)。在优化条件下诱导表达重组蛋白,利用Ni-NTA金属螯合层析、离子交换层析、分子筛层析和胰蛋白酶酶解技术获得高纯目的蛋白,SDS-PAGE分析表明,蛋白质分子量约为25kDa。采用座滴气相扩散法进行晶体制备和筛选,成功获得了蛋白质晶体,并通过X-射线衍射仪收集了晶体衍射花样。结合蛋白质晶体学方法,获得了有衍射的辣椒疫霉PcCRN20-C蛋白晶体,为进一步研究CRN蛋白的结构与病原菌致病机制提供参考资料。     

辣椒疫霉PcCRN20-C蛋白的表达纯化及结晶

CRN(crinkling and necrosis-inducing protein)为疫霉菌在与寄主互作过程中分泌的一类特有胞质效应因子,干扰寄主细胞正常的生理代谢和功能。采用PCR法从辣椒疫霉LT1534菌株c DNA中克隆PcCRN20-C基因。该基因序列长783bp,编码261个氨基酸。构建重组表达载体,并转化大肠杆菌BL21(DE3)。在优化条件下诱导表达重组蛋白,利用Ni-NTA金属螯合层析、离子交换层析、分子筛层析和胰蛋白酶酶解技术获得高纯目的蛋白,SDS-PAGE分析表明,蛋白质分子量约为25kDa。采用座滴气相扩散法进行晶体制备和筛选,成功获得了蛋白质晶体,并通过X-射线衍射仪收集了晶体衍射花样。结合蛋白质晶体学方法,获得了有衍射的辣椒疫霉PcCRN20-C蛋白晶体,为进一步研究CRN蛋白的结构与病原菌致病机制提供参考资料。     

植物免疫激酶AtCERK1的重组表达与结晶研究

植物免疫激酶中的CERK1(chitin elicitor receptor kinase 1)家族是能够感知细菌及真菌侵染的模式识别受体。此类受体蛋白可以通过识别多糖类的病原微生物相关分子,引起病原微生物相关分子模式触发的免疫反应,是植物产生先天性免疫应答以应对微生物感染的重要元件,同时也是诱导植物-微生物共生的关键蛋白质。为推进CERK1激酶区真实蛋白质三维空间构象的解析,本研究针对拟南芥源的CERK1蛋白构建了野生型及突变型AtCERK1的E. coli-pRSF原核表达系统,经原核表达得到带有6个His标签的融合蛋白,经镍柱亲和层析、离子交换层析和凝胶过滤层析等一系列纯化过程得到高纯度蛋白质样品后对其进行结晶条件筛选。最终, AtCERK1^F460V突变型成功在0.2 mol/L氟化铵和20%PEG3350溶液环境中析出蛋白质晶体。经上海光源BL17U1线站采集,蛋白质晶体X射线衍射数据的分辨率为3.2?。综上所述,本研究成功获得了高纯度的AtCERK1蛋白样品,且突变型蛋白质成功析出晶体;同时,利用X射线收取了一套中等分辨率的衍射数据,为AtCERK1介...     

灵芝-8基因的番茄果实特异性启动子植物表达载体的构建

构建含有灵芝-8（LZ-8）基因和番茄果实特异性E8启动子的重组载体,并将其转化到根瘤农杆菌中。通过PCR法获取LZ-8基因和E8启动子序列,将目的基因和E8启动子序列构建到植物表达载体pBI121中,获得果实特异性表达LZ-8蛋白的重组质粒。并采用PCR、限制性内切酶酶切和序列测定分析法,对重组质粒进行鉴定,将其转入根瘤农杆菌GV3101中。PCR法、限制性内切酶酶切图谱和序列测定分析均表明番茄果实特异性表达LZ-8蛋白的重组质粒构建成功。获得了含有LZ-8基因和E8启动子的重组质粒,并成功转化根瘤农杆菌,为下一步LZ-8蛋白在番茄果实中特异表达奠定基础。     

中华按蚊α-羧酸酯酶AsAe7的异源表达、纯化与结晶

【目的】羧酸酯酶(carboxylesterase,COE)是昆虫体内一类重要的解毒酶,与昆虫的抗药性相关。本研究旨在对中华按蚊Anopheles sinensis羧酸酯酶Ae7(Asae7)进行初步晶体学研究,为解析As Ae7的空间结构及探讨其分子功能奠定基础。【方法】首先对Asae7进行生物信息学分析,然后进行分子克隆,并利用原核表达系统在体外对Asae7进行重组表达;结合Ni-NTA金属螯合层析和葡聚糖凝胶层析方法纯化融合表达蛋白;通过葡聚糖凝胶层析和化学交联结果分析As Ae7的聚合状态;采用坐滴气相扩散法对As Ae7进行结晶筛选。【结果】生物信息学分析表明,As Ae7是亲水性蛋白,分子量为61.053 k D,无跨膜区和信号肽;3D结构预测结果分析显示,As Ae7采取的是α/β-水解酶超家族折叠模式。多序列比对结果表明,在不同昆虫中Ae7蛋白具有高度保守性。分子克隆得到中华按蚊As Ae7的编码基因Asae7序列,大小为1 626 bp。成功构建重组质粒p ET28aAsae7;在大肠杆菌Escherichia coli中表达的融合蛋白As Ae7主要分布在上清中。通过镍柱亲和层析和凝胶过滤层析纯化出了高纯度且稳定的目的蛋白;通过凝胶过滤层析和化学交联获得纯化的As Ae7主要呈单体状态;同时通过晶体筛选获得了As Ae7的晶体。【结论】运用结晶学的方法初步获得了As Ae7的晶体,为后续解析As Ae7的晶体结构以及在原子分辨率水平上直观阐释As Ae7参与代谢抗性的分子机制奠定了基础。     

效应蛋白LepB的表达,纯化及其亚克隆片段的结晶研究

为了研究嗜肺军团菌通过其效应蛋白发挥的致病机理,效应蛋白的结构和生物学功能研究是至关重要的。我们构建了效应蛋白LepB全长载体PFastBac1,应用Bac-to-Bac杆状病毒表达系统成功表达了全长LepB蛋白,并构建9个LepB亚克隆的原核表达载体PGEX-1,通过GST亲和层析,离子交换层析,凝胶过滤层析,纯化得到了纯度较高的蛋白片段。通过悬滴气相扩散法进行蛋白结晶筛选,获得了效应蛋白LepB片段480~679的蛋白晶体,为解析效应蛋白LepB的结构和生物学功能研究奠定基础。     

A novel adjuvant Ling Zhi-8 enhances the efficacy of DNA cancer vaccine by activating dendritic cells

DNA vaccine has been suggested to use in cancer therapy, but the efficacy remains to be improved. The immunostimulatory effect of a fungal immunomodulatory protein Ling Zhi-8 (LZ-8) isolated from Ganoderma lucidum has been reported. In this study, we tested the adjuvanticity of LZ-8 for HER-2/neu DNA vaccine against p185^neu expressing tumor MBT-2 in mice. We found that recombinant LZ-8 stimulated mouse bone marrow-derived dendritic cells (DCs) via TLR4 and its stimulatory effect was not due to any microbe contaminant. In addition, LZ-8 enhanced the ability of DCs to induce antigen-specific T cell activation in vitro and in a subunit vaccine model in vivo. Surprisingly, LZ-8 cotreatment strongly improved the therapeutic effect of DNA vaccine against MBT-2 tumor in mice. This increase in antitumor activity was attributed to the enhancement of vaccine-induced Th1 and CTL responses. Consistent with the results from DCs, the promoting effect of LZ-8 on DNA vaccine was diminished when the MBT-2 tumor cells were grown in TLR4 mutant mice. Thus, we concluded that LZ-8 may be a promising adjuvant to enhance the efficacy of DNA vaccine by activating DCs via TLR4.     

Complete amino acid sequence of an immunomodulatory protein, ling zhi-8 (LZ-8). An immunomodulator from a fungus, Ganoderma lucidium, having similarity to immunoglobulin variable regions

The complete amino acid sequence of a novel immunomodulatory protein, ling zhi-8 (LZ-8), isolated from a fungus, Ganoderma lucidium (Kino, K., Yamashita, A., Yamaoka, K., Watanabe, J., Tanaka, S., Ko, K., Shimizu, K., and Tsunoo, H. (1989) J. Biol. Chem. 264, 472-478), was determined by protein sequencing. The polypeptide consists of 110 amino acid residues with an acetylated amino end and has a molecular mass of 12,420 Da including an amino-end blocking group. There is no attachment site for an Asn-linked oligosaccharide chain, consistent with the very low carbohydrate content of LZ-8. These results indicate that the native form of LZ-8 with a molecular mass of 24 kDa is a homodimer of the LZ-8 polypeptide whose sequence is described here. Furthermore, the LZ-8 chain shows considerable similarity to the variable region of immunoglobulin heavy chain both in its sequence and in its predicted secondary structure. The interesting possibility that LZ-8 is related to an ancestral protein of the immunoglobulin superfamily is also discussed.     

灵芝lz8基因的克隆和原核表达及LZ-8蛋白的免疫印迹检测

根据已报道的lz8基因序列设计引物,以灵芝基因组DNA为模板,PCR扩增获得lz8基因。构建了原核表达载体pET30a-lz8,转化原核表达宿主菌RosettaDE3,IPTG诱导融合蛋白表达,并用Ni-NTA亲和层析柱对LZ-8蛋白进行分离纯化。将纯化的LZ-8蛋白用Freund佐剂乳化后注射到新西兰白兔体内,经数次加强免疫后采血分离抗血清,并以抗血清为探针建立了LZ-8蛋白的免疫印迹法定性检测方法。     

Extracellular Expression of a Functional Recombinant Ganoderma lucidium Immunomodulatory Protein by Bacillus subtilis and Lactococcus lactis

Bacillus subtilis and Lactococcus lactis are ideal hosts for the production of extracellular heterologous proteins of major commercial importance. A recombinant gene for the novel Ganoderma lucidium immunomodulatory protein LZ-8, recombinant LZ-8, was designed encoding the same amino acid sequence but using the preferred codons for both strains and was synthesized by overlapping extension PCR. Using the signal peptide (SP) from subtilisin YaB (SP_YaB), recombinant LZ-8 was expressed extracellularly in Bacillus subtilis and Lactococcus lactis. In the absence of SP_YaB, recombinant LZ-8 was expressed extracellularly in B. subtilis, but not in L. lactis. The three expressed recombinant LZ-8s showed different capacities for modulating the production of Th1 and Th2 cytokines by peripheral blood mononuclear cells and of tumor necrosis factor alpha by a macrophage cell line.     

Functional proteomic analysis reveals that fungal immunomodulatory protein reduced expressions of heat shock proteins correlates to apoptosis in lung cancer cells

BackgroundLing Zhi-8 (LZ-8) and GMI are two fungal immunomodulatory proteins (FIPs) with a similar structure and amino acid sequence and are respectively obtained from the medicinal mushroom Ganoderma lucidum and Ganoderma microsporum. They present the anti-cancer progression and metastasis. We previously demonstrated that LZ-8 reduces the tumor progression in lung cancer LLC1 cell-bearing mouse. However, it is unclear whether these FIPs induce changes in the protein expression profile in cancer cells and the mechanism for such a process is not defined.PurposeThis study determines the changes in the proteomic profile for tumor lesions of LLC1 cell-bearing mouse received with LZ-8 and the potential mechanism for FIPs in anti-lung cancer cells.MethodsThe proteomic profile of tumor lesions was determined using two-dimensional electrophoresis and a LTQ-OrbitrapXL mass spectrometer (LC-MS/MS). The biological processes and the signaling pathway enrichment analysis were performed using Ingenuity Pathway Analysis (IPA). The differentially expressed proteins were verified by Western blot. Cell viability was determined by MTT assay. Cell morphology was characterized using electron microscopy. Migration was detected using the Transwell assay. The apoptotic response was determined using Western blot and flow cytometry.ResultsObtained results showed that 21 proteins in the tumor lesions exhibited differential (2-fold change, p < 0.05) expression between PBS and LZ-8 treatment groups. LZ-8-induced changes in the proteomic profile that may relate to protein degradation pathways. Specifically, three heat shock proteins (HSPs), HSP60, 70 and 90, were significantly downregulated in tumor lesions of LLC1-bearing mouse received with LZ-8. Both LZ-8 and GMI reduced the protein levels for these HSPs in lung cancer cells. Functional studies showed that they inhibited cell migration but effectively induced apoptotic response in LLC1 cells in vitro. In addition, the inhibitors of HSP60 and HSP70 effectively inhibited cell migration and decreased cell viability of LLC1 cells.ConclusionsLZ-8 induced changes in the proteomic profile of tumor lesions which may regulate the HSPs-related cell viability. Moreover, inhibition of HSPs may be related to the anti-lung cancer activity.     

Isolation and characterization of a new immunomodulatory protein, ling zhi-8 (LZ-8), from Ganoderma lucidium

A novel protein with mitogenic activity in vitro and immunomodulating activity in vivo has been isolated from the mycelial extract of an Oriental medicinal fungus, ling zhi (Ganoderma lucidium). This protein was named ling zhi-8 (LZ-8) and its biochemical and immunological properties are described. LZ-8 was purified by two chromatographic systems, gel filtration and followed by ion-exchange, using an in vitro bioassay measuring blast-formation stimulatory activity toward mouse spleen lymphocytes to monitor purification. Analysis by several types of electrophoresis revealed a single band, with the molecular weight differing slightly depending on the system employed. Under reduced conditions, sodium dodecyl sulfate-polyacrylamide gel electrophoresis using the method of Laemmli, U.K. ((1970) Nature 227, 680-685) indicated an apparent Mr = 17,100, while under nonreduced conditions an apparent Mr = 17,500 was found; and, using Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a value of apparent Mr = 13,100 was obtained. LZ-8 has an isoelectric point of 4.4, and sugar analysis indicated a low carbohydrate content (1.3%). Half-cysteine, histidine, and methionine were not detected from the analysis of amino acid composition after further purification of LZ-8 by reversed-phase high performance liquid chromatography. LZ-8 was capable of hemagglutinating sheep red blood cells, but no such activity was observed toward human red blood cells (A, B, AB, and O types). In vivo, LZ-8 prevents the production of systemic anaphylaxis reaction in mice if it has been administered repeatedly, and reduction of antibody production is the suggested mechanism. The mechanisms of hemagglutination of sheep red blood cells and of blast-formation stimulation of mouse spleen cells are also discussed.     

An immunomodulatory protein, Ling Zhi-8, facilitates cellular interaction through modulation of adhesion molecules.

Ling Zhi-8 (LZ-8), a novel immunomodulatory protein, markedly enhanced the expression of CD11b, but not CD11a, CD13, CD14, CD18, CD33 or HLA-DR, on the U937 cell line in a dose-dependent fashion. It also induced ICAM-1 expression on vascular endothelial cells and significantly augmented gamma - interferon-induced cellular binding between vascular endothelial cells and U937. Furthermore, LZ-8 increased the expression of CD2, but not VLA4, VLA5 or LFA3, on MOLT4 and enhanced rosette formation between human T cells and sheep red blood cells. These data suggest that LZ-8 exerts its pharmacological effect by modulating adhesion molecules on immunocompetent cells.     

Reishi immuno-modulation protein induces interleukin-2 expression via protein kinase-dependent signaling pathways within human T cells

Ganoderma lucidum, a medicinal fungus is thought to possess and enhance a variety of human immune functions. An immuno-modulatory protein, Ling Zhi-8 (LZ-8) isolated from G. lucidum exhibited potent mitogenic effects upon human peripheral blood lymphocytes (PBL). However, LZ-8-mediated signal transduction in the regulation of interleukin-2 (IL-2) gene expression within human T cells is largely unknown. Here we cloned the LZ-8 gene of G. lucidum, and expressed the recombinant LZ-8 protein (rLZ-8) by means of a yeast Pichia pastoris protein expression system. We found that rLZ-8 induces IL-2 gene expression via the Src-family protein tyrosine kinase (PTK), via reactive oxygen species (ROS), and differential protein kinase-dependent pathways within human primary T cells and cultured Jurkat T cells. In essence, we have established the nature of the rLZ-8-mediated signal-transduction pathways, such as PTK/protein kinase C (PKC)/ROS, PTK/PLC/PKCalpha/ERK1/2, and PTK/PLC/PKCalpha/p38 pathways in the regulation of IL-2 gene expression within human T cells. Our current results of analyzing rLZ-8-mediated signal transduction in T cells might provide a potential application for rLZ-8 as a pharmacological immune-modulating agent.