黑曲霉脯氨酸蛋白内肽酶基因的克隆及其在酵母中的表达

以A．niger TCCC41013总RNA为模板,通过RT-PCR扩增含自身信号肽的脯氨酸蛋白内肽酶基因pep,将其克隆到pUCm-T载体上进行测序。测序结果表明基因全长1581bp,共编码526个氨基酸,包括22个氨基酸的信号肽序列和504个氨基酸的成熟肽序列。通过生物信息学方法对蛋白质的理化性质进行分析预测,脯氨酸蛋白内肽酶等电点为4．43,具有丝氨酸活性中心,属丝氨酸羧肽酶S28家族。以重组质粒pUCm．T-pep为模板,通过PCR扩增去除自身信号肽的pep,构建毕赤酵母表达载体pPIC9-peP,电转酵母宿主菌GS115。SDS-PAGE分析显示表达产物的分子量为60000Da左右,酶特异性底物法测定酶活力最高可达2275．4mU／mL。     

黑曲霉N-2植酸酶phy4基因的克隆及其重组酵母表达载体的构建

根据已发表的植酸酶phyA基因序列设计并合成1对引物,应用PCR技术,以黑曲霉N-2总DNA为模板,扩增出不包含假定信号肽序列的phyA基因,将其克隆到pMD18-T载体中,测定其核苷酸序列,并推导其氨基酸序列。该基因全长为1350bp,与已发表的黑曲霉NRRL3135的phyA基因的同源性为92．4％(不计内含子),编码1个含449个氨基酸残基的蛋白质,推导的氨基酸序列同源性为95．1％。将该基因与分泌型载体pPIC9K连接,构建了植酸酶基因的重组酵母表达载体pPIC9K／phyA。     

羊传染性脓疱病毒新疆流行株F1L基因克隆及表达

目的:为了探讨F1L重组蛋白作为羊传染性脓疱病毒亚单位疫苗的可行性。方法:以分离出羊传染性脓疱病毒ORFV-shz分离株为模板,扩增F1L基因片段,并将其克隆至pMD18-T载体中进行测序。构建原核表达载体pET-32a-F1L,转化至大肠埃希菌BL21,用SDS-PAGE及Western blot检测目的蛋白的表达情况及其反应原性。结果:PCR扩增出F1L基因全长1023bp,共编码340个氨基酸;推导的氨基酸序列中第1～70位氨基酸构成信号肽序列,第285～313位氨基酸为跨膜区。SDS-PAGE分析表明获得了约57.4kDa的融合蛋白,在Western-blotting检测中,融合蛋白可与羊传染性脓疱病毒阳性血清发生特异性反应,表明其具有良好的反应原性。结论:成功构建F1L基因的原核表达载体,为研究新疆地区羊传染性脓疱的防治及疫苗开发提供了科学依据。     

黑曲霉脯氨酸蛋白内肽酶基因的克隆与序列分析

以黑曲霉(A.niger)TCCC41013的总RNA作为模板,通过RT-PCR扩增出含自身信号肽的脯氨酸蛋白内肽酶基因,将其插入pUCm-T载体上,经PCR和酶切鉴定后进行测序并分析.所克隆的PEP基因全长为1 581bp,编码526个氨基酸残基,成熟肽为504个氨基酸残基.与GeneBank中已报道的A.niger CBS513.88的PEP序列同源性最高,达到99.75%.脯氨酸蛋白内肽酶是一种新型的丝氨酸蛋白酶,黑曲霉PEP与已克隆的其他菌种的PEP同源性不高.     

EB病毒融合基因重组BCG穿梭质粒的构建及表达

分别以卡介苗(BCG)和EB病毒融合基因cDNA为模板,通过PCR扩增得到139bp的BCG-Ag85B信号肽序列和2291bp的Z2A基因序列。将BCG-Ag85B信号肽序列与大肠杆菌-卡介苗穿梭表达载体pMV261重组,得到重组质粒pMVS。再将EB病毒融合基因序列Z2A亚克隆至pMVS中,得到重组质粒pMVZ2A,电转化导入BCG。SDS-PAGE分析结果表明,构建的重组质粒pMVZ2A经双酶切、PCR扩增及测序鉴定证实,克隆基因BCG-Ag85B信号肽和Z2A正确插入载体pMV261,电转化导入BCG,能够在BCG中分泌表达。     

桔青霉木聚糖酶基因克隆及其在毕赤酵母中的表达及活性分析

通过同源序列PCR克隆的方法,获得桔青霉(Penicillium citrinum)CR-2菌株的木聚糖酶编码基因xyl,该基因全长984 bp,编码327个氨基酸,无内含子序列,具有完整开放阅读框。其编码的氨基酸序列N端具有一段包含19个氨基酸的信号肽序列,并具有糖基水解酶第10家族(GH10)的保守催化域特征,推测该酶属于第10家族成员。将该基因与毕赤酵母表达载体pPIC9相连接构建重组载体pPIC9-XYL,电击转化至毕赤酵母GS115菌株中。挑选阳性重组子经测序、酶活性以及SDS电泳分析表明,xyl基因成功在毕赤酵母中分泌表达,重组酶活性可达214.15 IU/mL。该重组酶最适温度与最适pH分别为50℃和4.5,且具有良好的pH和热稳定性。     

信号肽序列对毕赤酵母表达外源蛋白质的影响

乙醇氧化酶启动子被分离、克隆 ,并建立了转化方法后 ,毕赤酵母已被发展成为一种高效的外源蛋白表达宿主。为了进一步提高外源蛋白质的分泌表达 ,对信号肽序列进行了研究。首先按毕赤酵母的偏爱密码合成了酿酒酵母的α因子信号肽序列MF4I,随后在MF4I信号肽序列的N端分别引入 1～ 10个毕赤酵母Aox1蛋白质的N端氨基酸 ,构成 10种不同的分泌信号肽序列 ,10种不同的分泌信号肽序列被用于植酸酶基因的毕赤酵母分泌表达。以上新的信号肽序列都可使植酸酶的分泌表达量增加 ,而以N端增加A、I、P三个氨基酸的信号肽序列引起的提高最大 ;和野生型的酿酒酵母α因子信号肽序列相比 ,使植酸酶分泌表达量增加 5倍 ,摇瓶中植酸酶的分泌表达量为 90mg/L。此外在MF4I信号肽的引导序列和内切蛋白酶间增加了EEAEAEAEP和K共 10个氨基酸 ,进一步提高信号肽的分泌效率 ,使表达又提高约 35 % ,使得摇瓶中酸性植酸酶的表达量达到 12 0mg/L ,是pPCI9K表达量的 8倍。     

近平滑假丝酵母(R)-专一性羰基还原酶基因的克隆与表达*

根据纯化得到的?-专一性羰基还原酶(rCR)蛋白质测序结果推导出的核苷酸序列设计引物,以筛选得到的近平滑假丝酵母(Candida parapsilosis)CCTCC M203011基因组为模板,通过PCR扩增目的片段,克隆后测序。核苷酸序列测定结果表明rcr基因全长1011bp,共编码336个氨基酸,分子量为35·9kD。将序列递交NCBI比对,与醇脱氢酶超家族成员序列同源性达99%。在大肠杆菌(Escherichia coli)JM109中表达rcr基因,重组     

转基因枸杞表达HIV-1壳体蛋白病毒样颗粒疫苗表达载体的构建

利用PCR技术扩增出人免疫缺陷病毒HIV-1MA₄-CA融合基因,将其克隆到pGEM-T载体中,测定其核苷酸序列,并推导其氨基酸序列。该基因全长为450bp,与已发表的HIV-1的全序列基因(AF324493)完全同源,编码一个含150个氨基酸残基的蛋白质。将该基因与分泌型表达载体pCAMBIA1305.2连接,同时将水稻中富含甘氨酸蛋白的信号肽序列(GRP)引入MA₄-CA融合基因,构建了含MA₄-CA基因的植物分泌表达载体pCAMBIA1305.2-MA₄-CA。     

双顺反子翻译偶联表达载体的构建及蚓激酶基因F238在大肠杆菌中的可溶性表达

为了实现外源蛋白在大肠杆菌中的可溶性表达,利用硫氧还蛋白作为分子伴侣构建双顺反子翻译偶联表达载体pDICT。将大肠杆菌硫氧还蛋白基因插入到pET22b载体NdeI和EcoR I位点之间,同时在硫氧还蛋白编码基因的终止密码子前加入核糖体结合位点,构建成双顺反子翻译偶联表达载体pDICT。将蚓激酶基因F238克隆到该载体,转化大肠杆菌BL21(DE3)并诱导表达。SDS-PAGE结果表明,所表达的蚓激酶F238是可溶性蛋白。利用血纤维蛋白法对表达产物进行活性测定,重组蚓激酶F238不仅具有纤溶酶活性,而且具有激活纤溶酶原的激酶活性。该双顺反子翻译偶联表达载体的构建,为在大肠杆菌中可溶性表达外源蛋白提供了新方法。     

Nucleotide sequence of cloned cDNA for human pancreatic kallikrein

Cloned cDNA sequences for human pancreatic kallikrein have been isolated and determined by molecular cloning and sequence analysis. The identity between human pancreatic and urinary kallikreins is indicated by the complete coincidence between the amino acid sequence deduced from the cloned cDNA sequence and that reported partially for urinary kallikrein. The active enzyme form of the human pancreatic kallikrein consists of 238 amino acids and is preceded by a signal peptide and a profragment of 24 amino acids. A sequence comparison of this with other mammalian kallikreins indicates that key amino acid residues required for both serine protease activity and kallikrein-like cleavage specificity are retained in the human sequence, and residues corresponding to some external loops of the kallikrein diverge from other kallikreins. Analyses by RNA blot hybridization, primer extension, and S1 nuclease mapping indicate that the pancreatic kallikrein mRNA is also expressed in the kidney and sublingual gland, suggesting the active synthesis of urinary kallikrein in these tissues. Furthermore, the tissue-specific regulation of the expression of the members of the human kallikrein gene family has been discussed.     

扩展青霉脂肪酶基因克隆、密码子优化及表达

【目的】克隆扩展青霉脂肪酶基因,实现具强催化活性的脂肪酶的异源高效表达。【方法】利用RT-PCR扩增扩展青霉CICC 40356脂肪酶(PEL)cDNA序列,利用重叠延伸PCR(Over-lap extension PCR)技术对PEL的10个稀有氨基酸密码子和表达载体pPIC9Kα信号肽的9个氨基酸密码子进行了优化,获得了改造过的脂肪酶基因PELM和表达载体pPIC9KM。并构建了带有脂肪酶自身信号肽的pPIC9K-PEL1、pPIC9KM-PELM1、pPIC3.5K-PEL1、pPIC3.5K-PELM1和不带有脂肪酶自身信号肽的pPIC9K-PEL2、pPIC9KM-PELM2六个重组质粒。利用对硝基苯酚棕榈酸酯(pNPP)为底物检测工程菌脂肪酶的酶活。在此基础上,对工程菌的酶学性质进行了研究。【结果】扩展青霉脂肪酶基因cDNA序列分析结果表明该序列与已报道PEL cDNA序列仅相差3个碱基,同源性高达99%。6个重组工程菌在甲醇诱导下,均表现出pNPP水解活性,28℃诱导100h时酶活达到最高,发酵上清的酶活分别为3.65 U/mL、30.49 U/mL、90.85 U/mL、212.05 U/mL、15.29 U/mL、76.32 U/mL。SDS-PAGE结果表明重组脂肪酶分子量均约28 kDa。酶学性质研究表明,重组脂肪酶PELM最适温度为35℃,最适pH为9.5,在pH7.0-10.0范围内该脂肪酶均较稳定,Ca2+和Mg2+对其有激活作用,Fe2+、Zn2+、Cu2+则有抑制作用,EDTA能使之快速失活。以不同碳链长度的对硝基苯酚酯为底物检测其底物特异性,结果显示其对中链酯(C8-C12)有较强的水解能力,最适底物为为C8的pNP酯。【结论】密码子优化后的扩展青霉脂肪酶基因在毕赤酵母中获得理想的表达,其酶活力比未优化的野生脂肪酶的提高了2.3-2.5倍,表明定点突变对其基因本身更改特有稀有密码子是实现PEL功能蛋白的异源高效表达的有效策略之一。     

Identification of two novel fibrinolytic enzymes from Bacillus subtilis QK02

Two fibrinolytic enzymes (QK-1 and QK-2) purified from the supernatant of Bacillus subtilis QK02 culture broth had molecular masses of 42,000 Da and 28,000 Da, respectively. The first 20 amino acids of the N-terminal sequence are AQSVPYGISQ IKAPALHSQG. The deduced protein sequence and its restriction enzyme map of the enzyme QK-2 are different from those of other proteases. The enzyme QK-2 digested not only fibrin but also a subtilisin substrate, and PMSF inhibited its fibrinolytic and amidolytic activities completely; while QK-1 hydrolyzed fibrin and a plasmin substrate, and PMSF as well as aprotinin inhibited its fibrinolytic activity. These results indicated QK-1 was a plasmin-like serine protease and QK-2 a subtilisin family serine protease. Therefore, these enzymes were designated subtilisin QK. The sequence of a DNA fragment encoding subtilisin QK contained an open reading frame of 1149 base pairs encoding 106 amino acids for signal peptide and 257 amino acids for subtilisin QK, which is highly similar with that of a fibrinolytic enzyme, subtilisin NAT (identities 96.8%). Asp32, His64 and Ser221 in the amino acid sequence deduced from the QK gene are identical to the active site of nattokinase (NK) produced by B. subtilis natto.     

米根霉糖化酶、类芽孢杆菌木聚糖酶融合蛋白的真核分泌表达

以米根霉(Rhizopus oryzae)3.866基因组DNA为模板,克隆得到糖化酶基因(glucoamylase gene, amyA),基因全长2 049 bp,编码604个氨基酸;以类芽孢杆菌(Paenibacillus sp.)H10-3基因组DNA为模板,克隆出基因木聚糖酶基因(xylanase A gene, xynA)的成熟肽编码序列,长636 bp,编码211个氨基酸。通过重叠延伸PCR(SOE-PCR)得到拼接片段amyA-l-xynA,并将其克隆到毕赤酵母表达载体pPIC9中,得到重组质粒pPIC9-amyA-l-xynA,重组质粒线性化后经电击转化到毕赤酵母(Pichia pastoris)GS115中,得到了表达成功的工程菌AX11。在AX11发酵上清液中同时检测到糖化酶活性(5.8 U/mL)和木聚糖酶活性(32.3 U/mL)。     

Bacillopeptidase F of Bacillus subtilis: purification of the protein and cloning of the gene.

We have purified a minor extracellular serine protease from Bacillus subtilis. Characterization of this enzyme indicated that it was most likely the previously reported enzyme bacillopeptidase F. The amino-terminal sequence of the purified protein was determined, and a "guess-mer" oligonucleotide hybridization probe was constructed on the basis of that sequence. This probe was used to identify and clone the structural gene (bpr) for bacillopeptidase F. The deduced amino acid sequence for the mature protein (496 amino acids) was preceded by a putative signal sequence of 30 residues and a putative propeptide region of 164 amino acids. The bpr gene mapped near pyrD on the chromosome and was not required for growth or sporulation.     

Characterization of an extracellular protease inhibitor of Bacillus brevis HPD31 and nucleotide sequence of the corresponding gene.

A novel proteinaceous protease inhibitor was isolated from the culture supernatant of Bacillus brevis HPD31. The protease inhibitor of B. brevis (designated BbrPI) was produced extracellularly in multiple forms having at least three different molecular weights. One of them, BbrPI-a, was purified to near homogeneity and only showed inhibitory activity toward serine proteases, such as trypsin, chymotrypsin, and subtilisin. BbrPI was presumed to form a trypsin-inhibitor complex in a molar ratio of 1:1. The inhibitor was found to be heat resistant at neutral and acidic pHs. The gene coding for BbrPI was cloned into Escherichia coli, and its nucleotide sequence was determined. The sequence suggested that BbrPI is produced with a signal peptide of 24 amino acid residues. The amino acid sequence of the protein deduced from the DNA sequence contained the amino acid sequences of amino termini of the inhibitors, a, b, and c, and their putative precursor determined chemically. The molecular weight of the precursor was about 33,000, and the molecular weights of inhibitors a, b, and c were about 22,000, 23,500, and 24,000, respectively. It is presumed that the secreted precursor protein, which is probably inactive, is cleaved by protease into several active protease inhibitor molecules. BbrPI shows no significant homology to the protease inhibitors described previously and is unique in not having any cysteine residues in its molecule.     

蚓激酶的克隆及其对BHK细胞的作用

蚯蚓具有活血化瘀的功效 ,在我国作为中药 (地龙 )使用已经有上千年的历史 .近年来发现蚯蚓体内存在溶血栓成分 ,称为蚓激酶 (ｌｕｍｂｒｕｋｉｎａｓｅ)或蚯蚓纤溶酶 (ｔｈｒｏｍｂｏｌｙｔｉｃｅｎｚｙｍｅｉｎｅａｒｔｈｗｏｒｍ) .自Ｎ .Ｎａｋａ ｊｉｍａ报道从蚯蚓中分离到蚓激酶以来[1] ,国内外已经有许多报道[2～ 6] ,主要侧重于天然提取物的生化研究 .本文通过ＲＴ ＰＣＲ从蚯蚓 (Ｌ .ｂｉｍａｓｔｕｓ)体内获得蚓激酶基因 ,进行表达并观察其对ＢＨＫ细胞的作用 .1　材料与方法1 1　材料正蚓科双胸蚓属蚯蚓 ;反转录试剂 ,质粒ｐｃ…