凡纳滨对虾溶菌酶基因在毕赤酵母中的分泌表达和活性检测

原核重组表达的凡纳滨对虾(Litopenaeus vannamei)溶菌酶蛋白主要以包涵体形式存在, 经变性和复性处理后活性仍较差。研究将凡纳滨对虾溶菌酶基因(Lvlyz基因)克隆至毕赤酵母分泌型表达载体pPIC9K中, 电击转化毕赤酵母GS115细胞, 经组氨酸营养缺陷培养基筛选和PCR检测获得转化子。对其进行连续甲醇诱导表达, 利用SDS-PAGE和C端携带的6×His标签,对发酵液上清进行Western blot检测, 结果表明19.3 kD左右的条带即是重组表达的溶菌酶蛋白。用溶壁微球菌平板抑菌法鉴定表达产物具有较强的抑菌能力。研究首次利用毕赤酵母真核表达系统实现对虾溶菌酶基因的可溶性表达, 并且表达产物的活性良好。       

Shrimp (Litopenaeus vannamei) trypsinogen production in Pichia pastoris bioreactor cultures

Recently, we engineered a Pichia pastoris Mut⁺ strain to produce and secrete recombinant Litopenaeus vannamei trypsinogen. Despite the observed toxicity of the recombinant shrimp trypsinogen to the P. pastoris cell host, when high density cell cultures in shake flasks with alanine in the induction medium were used recombinant shrimp trypsinogen could be produced. To further improve the product yield, in this work, we evaluated L. vannamei trypsinogen production in P. pastoris using a bioreactor and two recombinant P. pastoris strains with different methanol utilization (Mut) phenotypes. The effect of pH and temperature during the induction step on the trypsinogen production was also evaluated. The results indicate that temperature, pH, and Mut phenotypes influence the production of the recombinant protein, with almost no observed effect on cell growth. All cultures with the Mut⁺ strain had significant operational difficulties, such as in lowering the induction temperature, maintaining dissolved oxygen (DO) above 20%, and maintaining the methanol concentration at a constant value, and showed a decrease in metabolic activity due to trypsinogen toxicity to the cell host. In the culture with the Mut^s strain, however, the temperature, methanol concentration, and DO could be more easily controlled, the temperature could be easily decreased, and the trypsinogen caused the lowest toxicity to the host cells. After 96 h of Mut^s strain induction (pH 6 and 25°C), about 250 mg/L recombinant trypsinogen was detected in the culture medium. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013     

B→O血型转变工具酶α-半乳糖苷酶cDNA克隆及表达

 α-半乳糖苷酶是实现 B→O血型转变、制备通用型血的关键工具酶 .利用反转录 PCR方法从中国海南 Catimor咖啡豆中克隆α-半乳糖苷酶 c DNA,插入嗜甲基酵母 P.pastoris分泌表达载体 p PIC9K中 ,转化 P.pastoris GS1 1 5,筛选高表达重组菌株 .经甲醇诱导表达 7d后 ,发酵液总蛋白分泌量约 1 .2 mg/ml,SDS- PAGE呈现约 41 k D特异表达带 ,与专一性底物对 -硝基 -苯基 -α- D-吡喃半乳糖苷反应证明 ,表达产物具有 α-半乳糖苷酶活性 ,最高达到 1 8U/ml.初步实验表明 ,表达的 α-半乳糖苷酶可酶解 B型红细胞 ,成功实现 B→O血型转变 .     

鲤鱼生长激素在毕赤酵母中的表达

 将编码鲤鱼 (Cyprinuscarpio )生长激素 (GH)成熟肽的cDNA克隆到毕赤酵母 (P .pastoris)胞内表达载体pHIL D2中 ,构建重组表达质粒pHIL D2 GH .转化组氨酸缺陷型酵母GS115,获得表达鲤鱼GH的酵母工程菌 .经甲醇诱导 ,SDS PAGE和Western印迹检测表明 ,鲤鱼GH在酵母中得到表达 ,表达产物在胞内以可溶状态存在 ,具有鲤鱼GH的免疫活性 .用诱导后的酵母投喂罗非鱼 ,实验结果证实所构建的工程菌具有明显的促生长作用     

Production of recombinant great sturgeon (Huso huso,Linnaeus, 1758) growth hormone (GH) by Pichia pastoris (Guillierm, 1956)

In this research, the encoding cDNA of growth hormone (GH) was cloned from the pituitary gland of great sturgeon Huso huso (three adults: two females and one male, 7–9 years old, 70–90 kg, reared in concrete ponds). In order to obtain the great sturgeon recombinant GH expression in Pichia pastoris, the mature encoding cDNA was first cloned in TA vector PTZ57R and then sequenced. After confirmation of the correct GH sequence, the GH coding sequence was subcloned into pHILS1 expression vector. The yeast Pichia pastoris GS115 strain was transformed with the expression plasmid. Results obtained from this study showed that great sturgeon GH recombinants were expressed upon induction with methanol and exported into the medium. The level of expression was examined using RNA analysis, SDS‐PAGE, and western blot analysis. RNA analysis of the recombinant strains showed a sharp, specific band in 800 bp. The specific band in transformants indicated the presence of GH RNA in the yeast. SDS‐PAGE and western blot analysis showed a specific 21 kDa band for the growth hormone. Culture conditions were optimized for pH = 6 and incubation time (after 24 h induction, peaking at 72 h) for maximal protein production. The results provide useful information for the future production of recombinant growth hormones in other sturgeon species.     

aiiA基因表达载体的构建及其在毕赤酵母中的表达

构建携带N-酰基高丝氨酸内酯酶基因(aiiA)的重组毕赤酵母表达载体pPIC3.5K-aiiA,采用电转化方法转入毕赤酵母GS115,经营养缺陷型培养基、表型鉴定和高G418浓度筛选获得高拷贝表达盒的酵母转化子,用0.5%甲醇诱导表达,RT-PCR鉴定可检测到重组酵母中编码目的基因成熟肽的mRNA,SDS-PAGE和Western blot检测结果表明,aiiA基因在毕赤酵母中成功表达,用指示菌紫色杆菌CV026检测发现目的蛋白具有降解N-酰基高丝氨酸内酯的活性。     

Ⅰ型纤溶酶原激活物抑制剂cDNA在P.pastoris酵母菌中的表达和鉴定

将编码３７９个氨基酸残基的ＰＡＩ－１ｃＤＮＡ插入到含ＡＯＸ１启动子和ＰＨＯ１分泌信号肽序列的甲醇营养型酵母载体中,构建成表达质粒ｐＹＩＳ－１．表达质粒转化Ｐ．ｐａｓｔｏｒｉｓ甲醇营养型酵母细胞,筛选Ｈｉｓ＋Ｍｕｔ－表型的转化子,经低密度摇瓶培养,１％甲醇诱导表达７ｄ后,培液经ＳＤＳ－ＰＡＧＥ分析,ＰＡＩ－１生物活性测定和Ｗｅｓｔｅｒｎｂｌｏｔ证实表达出分子量为４３～５１ｋＤ的４条ＰＡＩ－１条带．表达的ＰＡＩ－１能有效地分泌到培液中,占培液总蛋白的２６％左右,达４ｍｇ／Ｌ培液;其比活性为１．１６×１０４ＡＵ／ｍｇ．不同分子量ＰＡＩ－１可能与其糖基化程度不同有关     

多拷贝毕赤酵母重组菌表达GCL摇瓶优化和高密度发酵

目的:构建高效表达白地霉脂肪酶的毕赤酵母重组菌株,并对筛选得到的菌株进行摇瓶发酵条件优化和分批补料高密度发酵工艺研究。方法:将诱导型表达载体pPIC9K-gcl电转化至毕赤酵母GS115。通过橄榄油-罗丹明B平板和摇瓶发酵筛选高脂肪酶活力的重组菌株,运用基于TaqMan探针的实时荧光定量PCR 法确定其拷贝数,并对菌株进行摇瓶发酵条件优化。在此基础上,研究重组菌在3L 发酵罐中的高密度发酵工艺。结果:筛选得到一株具有3 个白地霉脂肪酶基因拷贝的菌株GS115/pPIC9K-gcl 78#,初始酶活力为220 U/ml。当摇瓶发酵条件为甲醇诱导96 h,每24 h甲醇添加量1 %,接种量2 %,培养基初始pH 7.0,500 ml摇瓶装液量50 ml,甲醇诱导温度25℃ 时酶活力达735 U/ml。3L 发酵罐高密度发酵176.5 h,酶活力达到3360 U/ml,总蛋白含量达到4.30 g/L,且发酵过程中细胞活性一直保持在96 % 以上。结论:基因拷贝数与重组菌株的产酶水平呈正相关,摇瓶优化可显著提高重组菌株的产酶能力,为白地霉脂肪酶的工业化生产奠定了技术基础。     

乙型肝炎病毒X基因真核表达载体的构建及其在巴斯德毕赤酵母中的表达

目的：在巴斯德毕赤酵母中表达乙型肝炎病毒（HBV）X蛋白,为探讨HBVX蛋白与慢性乙型肝炎及肝细胞癌发生的关系奠定基础。方法：用PCR方法扩增X基因序列,并分别在上下游引入XhoⅠ和XbaⅠ酶切位点,插入pPICZαA载体,转化大肠杆菌TOP10,筛选阳性克隆,对其进行PCR和双酶切及测序鉴定,构建HBVX蛋白毕赤酵母表达质粒pPICZαA-HBx;电击转化毕赤酵母GS115,对阳性克隆进行诱导表达后经SDS-PAGE和Western blotting鉴定目的蛋白。结果：双酶切pPICZαA-HBx后,琼脂糖电泳可分别见到大小约为3.1kb和465bp的片段,表明目的片段已插入载体中,序列测定表明其含有完整的X基因片段,Western blotting结果显示含有pPICZαA-HBx的毕赤酵母GS115能分泌表达X蛋白。结论：构建了毕赤酵母表达载体pPICZαA-HBx,并能在毕赤酵母GS115中分泌表达X蛋白。     

恶性疟原虫膜蛋白Pfs25在毕赤酵母中的组成型表达

目的:Pfs25蛋白是传播阻断型恶性疟疾疫苗的侯选抗原,在毕赤酵母中表达Pfs25蛋白,并对表达产物进行鉴定。方法:参照GenBank中公布的pfs25基因序列,通过毕赤酵母喜好密码子分析人工合成目的基因;采取定向克隆策略构建重组表达质粒pfs25/pGAPZαA,经BstXⅠ线性化,电转染法转化酵母菌株GS115,在Zeocin抗性的筛选培养基上获得表达目的基因的pfs25/pGAPZαA/GS115重组酵母菌,SDS-PAGE和Western印迹检测表达产物;通过在YPD培养基上传代培养和目的基因表达,验证重组菌株的遗传稳定性。结果:在毕赤酵母中表达了Pfs25蛋白,且重组菌株遗传性质稳定。结论:为研制基于Pfs25蛋白的传播阻断型恶性疟疾疫苗奠定了基础。     

在甲醇酵母Pichia pastoris胞内表达有活性的辣根过氧化物酶

为了开辟在甲醇酵母 Pichia pastoris中表达 HRP的新途径 ,将编码成熟 HRP同功酶 C基因克隆到表达载体 p PIK3.5K中 .p PIK3.5KHRP转化 GS1 1 5后 ,用 PCR筛选阳性 P.pastoris重组株 ,并用甲醇进行诱导 . Western印迹杂交分析表明目标蛋白 (约为 38k D)能被天然 HRP的多克隆抗体所识别 ,因此活性辣根过氧化物酶已在 P.pastoris胞内表达 .筛选菌株中显示了明显的过氧化物酶活性 ,同时诱导过程中血红素和 Ca Cl2 的加入对过氧化物酶的活力影响不大     

高温α-淀粉酶基因突变体在大肠杆菌、毕赤酵母中的表达

对地衣芽孢杆菌(Bacillus licheniformis)高温α-淀粉酶(amyE)基因进行改造获得的基因突变体(amyEM),通过PCR扩增,将此基因分别克隆至大肠杆菌表达载体pBV220和毕赤酵母表达载体pPIC9K上,并分别转化大肠杆菌DH5α和毕赤酵母GS115感受态细胞,获得重组大肠杆菌和重组毕赤酵母。通过表达产物的酶活性检测和SDS-PAGE分析,证明突变α-淀粉酶(AmyEM)在大肠杆菌、毕赤酵母中获得有效表达。对重组大肠杆菌产生的α-淀粉酶的粗酶性质分析表明,此酶分子量约为55kDa。其最适反应温度为80℃~90℃,与野生型基因相比,其最适pH均为6.0,但不同的是突变体在pH 5.0~5.5时表现出较高的酶活力;在毕赤酵母细胞的表达产物可分泌至胞外。由于酵母可对蛋白进行糖基化,酶分子量增加到60kDa,最适pH也改变为5.5。此高温α-淀粉酶突变体所具有的在微酸性环境具有较高酶活力的性质,具有重要的潜在工业应用价值。     

Degradation of HSA-AX15(R13K) when expressed in Pichia pastoris can be reduced via the disruption of YPS1 gene in this yeast

Expression of recombinant protein HSA-AX15(R13K) in Pichia pastoris GS115 strain produced both the intact protein and its two degradation products with molecular weights of around 43kDa and 66.2kDa, respectively. To reduce or avoid the degradation, a modified P. pastoris GS115 stain, in which YPS1 gene was disrupted, was constructed via homologous recombination and used as a host strain for the HSA-AX15(R13K) expression. After 60h of induction during culture, it was found that the degradation product of around 66.2kDa was reduced significantly in the supernatant of yps1-disrupted strain compared with that in the supernatant of wild-type strain. By the Western blot analysis of culture supernatants from wild-type and yps1-disrupted strains expressing HSA-AX15(R13K), the significant improvement was also seen in the degradation product of around 43kDa. Comparison of cell growth between the two strains demonstrated a similar growth tendency, thereby indicating that the disruption of YPS1 gene has no effect on the normal physiology of GS115 strain. Following induction for 60h, the yield of intact HSA-AX15(R13K) in the yps1 disruptant was three-fold higher than that in the wild-type strain. Therefore, such a P. pastoris mutant deficient in YPS1 activity is suitable for the high-level expression of recombinant protein HSA-AX15(R13K).     

Expression, purification, and activity identification of Alfimeprase in Pichia pastoris

Alfimeprase (ALF) is a truncated form of non-hemorrhagic zinc metalloproteinase fibrolase. In order to achieve a high level secretion and full activity expression of ALF, the Pichia pastoris (P. pastoris) expression system was used. ALF coding sequence fused with a 6 *histidine tag and an enterokinase recognition site at the N-terminus was cloned into the expression vector pPIC9K and then expressed in P. pastoris strains of GS115 and KM71 by methanol induction. SDS-PAGE and Western blotting analysis showed that the secreted recombinant ALF (rALF) had a molecular weight of 23.8 kDa and was bound specifically to mouse anti-His. tag monoclonal antibody. Under the optimized culture parameters of pH value, initial A(600) value, methanol daily addition concentration and induction time length, the production of rALF reached up to 510 mg/L and 465 mg/L of the GS115 and KM71 transformants, respectively. It also appeared that KM71 was producing a more pure protein than GS115 while GS115 was producing more rALF per unit volume. Through one-step affinity chromatography, the purity of rALF was as high as 96%. The fibrinolytic activity of rALF revealed by the modified fibrin plate method indicated that the protein was efficiently secreted and functionally expressed, and thrombolysis of rALF was demonstrated to be dose-dependent and time-relative. The improved expression system will facilitate further studies and industrial production of ALF.     

Cell bank characterization and fermentation optimization for production of recombinant heavy chain C-terminal fragment of botulinum neurotoxin serotype E (rBoNTE(H(c)): antigen E) by Pichia pastoris

A process was developed for production of a candidate vaccine antigen, recombinant C-terminal heavy chain fragment of the botulinum neurotoxin serotype E, rBoNTE(H(c)) in Pichia pastoris. P. pastoris strain GS115 was transformed with the rBoNTE(H(c)) gene inserted into pHILD4 Escherichia coli-P. pastoris shuttle plasmid. The clone was characterized for genetic stability, copy number, and BoNTE(H(c)) sequence. Expression of rBoNTE(H(c)) from the Mut(+) HIS4 clone was confirmed in the shake-flask, prior to developing a fed-batch fermentation process at 5 and 19 L scale. The fermentation process consists of a glycerol growth phase in batch and fed-batch mode using a defined medium followed by a glycerol/methanol transition phase for adaptation to growth on methanol and a methanol induction phase resulting in the production of rBoNTE(H(c)). Specific growth rate, ratio of growth to induction phase, and time of induction were critical for optimal rBoNTE(H(c)) production and minimal proteolytic degradation. A computer-controlled exponential growth model was used for process automation and off-gas analysis was used for process monitoring. The optimized process had an induction time of 9 h on methanol and produced up to 3 mg of rBoNTE(H(c)) per gram wet cell mass as determined by HPLC and Western blot analysis.     

Synthesis of Drosophila melanogaster acetylcholinesterase gene using yeast preferred codons and its expression in Pichia pastoris

To improve the expression level of recombinant Drosophila melanogaster AChE (R-DmAChE) in Pichia pastoris, the cDNA of DmAChE was first optimized and synthesized based on the preferred codon usage of P. pastoris. The synthesized AChE cDNA without glycosylphosphatidylinositol (GPI) signal peptide sequence was then ligated to the P. pastoris expression vector, generating the plasmid pPIC9K/DmAChE. The linearized plasmid was homologously integrated into the genome of P. pastoris GS115 via electrotransformation. Finally seven transformants with high expression level of R-DmAChE activity were obtained. The highest production of R-DmAChE in shake-flask culture after 5-day induction by methanol was 718.50units/mL, which was about three times higher than our previous expression level of native DmAChE gene in P. pastoris. Thus, these new strains with the ability to secret R-DmAChE in the medium could be used for production of R-DmAChE to decrease the cost of the enzyme expense for rapid detection of organophosphate and carbamate insecticide residues.     

用GAP启动子在毕节酵母中组成型表达人血管抑制素

为探索用GAP启动子(PGAP)取代AOX1启动子(PAOX1),在毕节酵母(P．pastortis)中组成型表达外源蛋白的可能性,应用PCR方法从P．pastoris染色体中扩增了GAP启动子,以其取代诱导型表达载体pPIC9K上的PAOX1,构建了组成型表达载体pGAP9K。将人血管抑制素(AS)基因重组于pGAP9K的多克隆位点,获得含As基因的重组质粒pGAP9K-AS。转化P．pastorisGSll5,对获得的高拷贝转化子P．pastorisGSll5(pGAP9K-AS)进行组成型表达,同时以诱导型转化子P．pastoris GSll5(pPIC9K-AS)作为对照。SDS-PAGE结果显示：组成型转化子于培养4d后AS的表达水平已达到高峰,分泌量为58mg／L;而诱导型转化子诱导4d后表达的AS仅是组成型表达的70％,诱导6d后达到高峰,表达量也只是组成型表达系统表达高峰时(4d)的86％。CAM分析和抗癌实验结果显示：P．pastortis GS115(pGA．P9K-S)和P．pastoris GS115(pPIC9K-AS)表达的AS均具有抑制血管生成和C57BL／6J实验小鼠的B16黑色素瘤的生长,其平均瘤重抑制率分别达到90．61％和90．54％。以上结果表明,以GAP启动子构建的组成型表达系统具有发酵时间较短、表达水平较高、不用甲醇诱导、操作系统比较简单等优点,PGAP可以取代PAOX1在P．pastoris中表达AS及其他外源蛋白。     

High-level expression of recombinant phospholipase C from Bacillus cereus in Pichia pastoris and its characterization

The phospholipase c (plc) gene from Bacillus cereus was cloned into the pPICZC vector and integrated into the genome of Pichia pastoris. The phospholipase C (PLC) when expressed in P. pastoris was fused to the alpha-factor secretion signal peptide of Saccharomyces cerevisiae and secreted into a culture medium. Recombinant P. pastoris X-33 had a clear PLC band at 28.5 kDa and produced an extracellular PLC with an activity of 678 U mg(-1) protein which was more than a recombinant P. pastoris GS115 (552 U mg(-1) protein) or KM71H (539 U mg(-1) protein). The PLCs were purified using a HiTrap affinity column with a specific activity of 1335 U mg(-1) protein by P. pastoris GS115, 1176 U mg(-1) protein by P. pastoris KM71H and 1522 U mg(-1) protein by P. pastoris X-33. The three recombinant PLCs had high PLC activity in the low pH range of 4-5 and higher thermal stability (e.g. stable at 75 degrees C) than the wild-type PLC from B. cereus . Some organic solvents, surfactants and metal ions, e.g. methanol, acetone, Co(2+) and Mn(2+) etc., also influenced the activity of the recombinant PLCs.     

狐狸生长激素基因的克隆及其在毕赤酵母中的表达

为制备重组狐狸生长激素(fGH),采用RT-PCR方法,从银狐垂体中扩增fGHcDNA基因,利用SnaBI和NotI位点将fGH基因插入到酵母分泌型表达载体pPIC9K中α-因子信号肽的下游,构建成fGH基因的酵母分泌型表达载体pPIC9K/fGH,载体经SalI酶切线性化后,通过电转移将线性化的pPIC9K/fGH转化到组氨酸缺陷型酵母宿主菌GS115中。然后利用不含氨基酸的以葡萄糖为碳源的培养基(MD)和以甲醇为碳源的培养基(MM)筛选出组氨酸His+型和甲醇利用正型(Mut+)酵母重组体,再经G418加压筛选出高拷贝fGH基因的重组酵母,经摇瓶发酵培养和甲醇诱导使fGH进行分泌表达。结果表明本实验扩增的fGH基因序列与GenBank发表的序列基本一致,发酵液经SDS-PAGE和Western blotting检测证明构建的重组酵母能够分泌表达fGH,表达的fGH占发酵液总蛋白的34%,表达量达119mg/L发酵液。     

Synthesis and high expression of chitin deacetylase from Colletotrichum lindemuthianum in Pichia pastoris GS115

A gene, ClCDA, encoding chitin deacetylase from Colletotrichum lindemuthianum, was optimized according to the codon usage bias of Pichia pastoris and synthesized in vitro by overlap extension PCR. It was secretorily expressed in P. pastoris GS115 using the constitutive expression vector pHMB905A. The expression level reached the highest with 110 mg/l culture supernatant after 72 h of methanol induction, which comprised 77.27 U/mg chitin deacetylase activity. SDS-PAGE, mass spectrometry, and deglycosylation assays demonstrated that partial recombinant protein was glycosylated with an apparent molecular mass of 33 kDa. The amino acid sequences of recombinant proteins were confirmed by mass spectrometry.