BioVector? pPIC6 畢赤酵母表達(dá)質(zhì)粒載體

BioVector? pPIC6 Pichia pastoris Expression Plasmid Vector

第一部分 中文說明

一 產(chǎn)品基本信息與遺傳學(xué)背景

• 載體名稱：BioVector? pPIC6 (分 A, B, C 三種閱讀框架亞型)

• 產(chǎn)品類型：畢赤酵母（Pichia pastoris）重組蛋白表達(dá)質(zhì)粒載體

• 復(fù)制子類型：

  • 大腸桿菌復(fù)制子：pUC origin（高拷貝，用于在大腸桿菌中的質(zhì)粒擴(kuò)增與克?。?。

  • 酵母整合定位：不含酵母自主復(fù)制子（ARS），依靠同源重組整合至畢赤酵母基因組中，實(shí)現(xiàn)高度穩(wěn)定的遺傳表達(dá)。

• 抗性篩選標(biāo)記（Dual Selection Markers）：

  • 大腸桿菌篩選：Blastcidin（殺稻瘟菌素抗性基因 bsd），由特異性啟動子驅(qū)動。

  • 酵母篩選：Blasticidin（殺稻瘟菌素抗性）。該載體利用單一的 Blasticidin（bsd）抗性基因，同時實(shí)現(xiàn)大腸桿菌（E. coli）和畢赤酵母（P. pastoris）的雙宿主高效選擇篩選。

• 分子大小：約 3.4 kb（千堿基對）。

• 生物安全級別：1級（BSL-1）。

二 核心功能元件與轉(zhuǎn)錄調(diào)控圖譜

pPIC6 載體專為在巴斯德畢赤酵母中進(jìn)行高水平、可誘導(dǎo)性重組蛋白表達(dá)而設(shè)計(jì)。其經(jīng)典轉(zhuǎn)錄調(diào)控元件排列如下：

1. AOX1 啟動子（5' AOX1 Promoter）：源自畢赤酵母醇氧化酶 1 基因的強(qiáng)啟動子。受到甲醇（Methanol）的嚴(yán)格高度誘導(dǎo)調(diào)控，在甘油或葡萄糖等碳源中處于完全壓制狀態(tài)，加入甲醇后被極速激活，驅(qū)動下游目標(biāo)蛋白的大規(guī)模高效轉(zhuǎn)錄。

2. 多克隆位點(diǎn)（MCS）：提供了豐富的內(nèi)切酶單一切點(diǎn)，并分為 pPIC6 A, B, C 三種變體，每種變體在 MCS 區(qū)發(fā)生 1-2 個堿基的交錯移動，用以方便地將目的基因片段調(diào)整至正確的轉(zhuǎn)錄翻譯閱讀框架（Reading frame）內(nèi)。

3. C-端融合純化標(biāo)簽（C-terminal Tags）：

   • Myc 標(biāo)簽（Myc Epitope）：便于使用抗 Myc 抗體進(jìn)行 Western Blot、免疫共沉淀（Co-IP）等常規(guī)蛋白質(zhì)檢測。

   • Polyhistidine (6xHis) 標(biāo)簽：位于最末端，便于利用固定化金屬親和層析（IMAC，如 Ni-NTA 磁珠或填料）對重組表達(dá)產(chǎn)物進(jìn)行高純度一步法提純。

4. AOX1 轉(zhuǎn)錄終止子（3' AOX1 Transcription Terminator）：提供高效的 mRNA 聚腺苷酸化（Polyadenylation）信號和轉(zhuǎn)錄終止位點(diǎn)，確保重組 mRNA 的分子穩(wěn)定性和高效翻譯。

5. 整合原理（Genome Integration Mechanism）：在轉(zhuǎn)化畢赤酵母前，質(zhì)粒需要通過特定的限制性內(nèi)切酶（如 BstXI 或 PmeI）在 AOX1 啟動子區(qū)域內(nèi)進(jìn)行單切點(diǎn)線性化（Linearization）。線性化后的質(zhì)粒通過同源重組，以單拷貝或多拷貝的形式插入到酵母基因組的 AOX1 位點(diǎn)上。

三 質(zhì)粒擴(kuò)增、轉(zhuǎn)化與酵母篩選標(biāo)準(zhǔn)操作步驟

1. 大腸桿菌中的質(zhì)粒擴(kuò)增（Plasmid Propagation）：

   • 推薦宿主：大腸桿菌 TOP10、DH5alpha 或其它常規(guī)克隆感受態(tài)菌株。

   • 篩選培養(yǎng)基：使用 Low Salt LB 培養(yǎng)基（低鹽 LB 固體/液體：含 10 g 胰蛋白胨、5 g 酵母提取物、5 g 氯化鈉 NaCl/每升，pH 7.5）。注：Blasticidin 抗生素在常規(guī)高鹽 LB 培養(yǎng)基中會因離子強(qiáng)度過高而失活，必須嚴(yán)格使用低鹽配方。

   • 抗生素工作濃度：大腸桿菌篩選時加入 50 μg/ml 至 100 μg/ml 的殺稻瘟菌素（Blasticidin）。37攝氏度擴(kuò)增過夜后進(jìn)行質(zhì)粒中提或大提。

2. 畢赤酵母重組轉(zhuǎn)化與篩選（Yeast Transformation）：

   • 常用酵母宿主菌株：GS115（His4- 缺陷型菌株）、KM71H、X-33 等。

   • 線性化準(zhǔn)備：使用純化后的質(zhì)粒，選擇 AOX1 啟動子內(nèi)的單一切點(diǎn)酶進(jìn)行徹底線性化，電泳檢查確認(rèn)完全線性化后，通過苯酚-氯仿抽提或柱純化回收，溶解于無菌去離子水中。

   • 電轉(zhuǎn)化操作：制備畢赤酵母電轉(zhuǎn)化感受態(tài)細(xì)胞。將約 5-10 μg 線性化質(zhì)粒與 80 μl 感受態(tài)細(xì)胞混合，移入預(yù)冷的 0.2 cm 電轉(zhuǎn)杯中。執(zhí)行畢赤酵母標(biāo)準(zhǔn)電擊程序（如 1.5 kV, 25 μF, 200 Ω）。

   • 復(fù)蘇與鋪板篩選：電擊后立即加入 1 ml 冰刻的 1 M 山梨醇（Sorbitol）溶液，重懸細(xì)胞并置于 30 攝氏度溫育復(fù)蘇 1 到 2 小時。隨后將菌液涂布于含有 100 μg/ml 至 300 μg/ml Blasticidin 的 YPD 固體選擇性培養(yǎng)基平板上。置于 30 攝氏度恒溫培養(yǎng)箱中，靜置孵育 3 到 5 天，直至重組整合成功的陽性單菌落生長成熟。

四 核心科研應(yīng)用方向

1. 胞內(nèi)高豐度重組蛋白的可誘導(dǎo)性表達(dá)：pPIC6 是無分泌信號肽的宿主表達(dá)載體，目的蛋白主要積聚在畢赤酵母細(xì)胞質(zhì)（Cytoplasm）中。常用于表達(dá)不需要進(jìn)行復(fù)雜糖基化修飾、但在大腸桿菌中易形成包涵體的各種功能性酶類、結(jié)構(gòu)蛋白及可溶性細(xì)胞因子的體外大規(guī)模制備。

2. 多拷貝重組子的快速高濃度抗生素篩選（Multi-copy Screening）：通過在酵母轉(zhuǎn)化平板中逐步提高 Blasticidin 的抗生素濃度（例如從 300 μg/ml 提高至 1000 μg/ml 甚至更高），可以高效直接地篩選出基因組中發(fā)生了多拷貝串聯(lián)整合（Multi-copy integration）的畢赤酵母超級工程菌株，從而大幅提升目的重組蛋白的終表達(dá)產(chǎn)量。

3. 胞內(nèi)蛋白修飾與體外交互作用純化研究：利用 C-端內(nèi)源集成的 Myc 和 6xHis 雙標(biāo)簽系統(tǒng)，重組表達(dá)的目標(biāo)蛋白不僅可以用于高純度的親和層析提純，還能直接用于體外蛋白質(zhì)-蛋白質(zhì)相互作用（如 Pull-down 實(shí)驗(yàn)）、細(xì)胞內(nèi)蛋白質(zhì)定位分析及質(zhì)譜學(xué)分析研究。

PART 2 ENGLISH SECTION

I General Information and Genetic Background

• Vector Name: BioVector? pPIC6 (Available in three reading frame variants: pPIC6 A, B, and C)

• Product Type: Pichia pastoris heterologous protein expression plasmid vector.

• Replicon Blueprint:

  • E. coli Replicon: pUC origin (High-copy number framework engineered for high-yield propagation in standard bacterial hosts).

  • Yeast Genomic Targeting: Lacks a yeast autonomous replication sequence (ARS). Relies strictly on homologous recombination to stably integrate directly into the Pichia pastoris genome for stable inheritance.

• Dual Selection Marker Framework:

  • Bacterial Selection: Blasticidin resistance (bsd gene) driven by a dedicated prokaryotic promoter sequence.

  • Yeast Selection: Blasticidin resistance. The vector utilizes a single Blasticidin (bsd) resistance marker to achieve high-efficiency selection across both E. coli and P. pastoris expression systems.

• Molecular Size: Approximately 3.4 kb (kilobase pairs).

• Biosafety Level: BSL-1.

II Core Structural Elements and Transcriptional Map

The pPIC6 vector is engineered to drive high-level, methanol-inducible expression of recombinant targets inside Pichia pastoris. The arrangement of its core transcription elements is detailed below:

1. 5' AOX1 Promoter: A strong promoter derived from the Pichia pastoris alcohol oxidase 1 gene. It is tightly regulated and heavily repressed in the presence of carbon sources like glycerol or glucose, but rapidly switches on upon the addition of Methanol to drive heavy transcriptional output.

2. Multiple Cloning Site (MCS): Features a robust selection of unique restriction endonuclease recognition sites. Distributed across three reading frame vectors (pPIC6 A, B, and C), each variant shifts the MCS by 1 or 2 nucleotides to facilitate proper in-frame alignment of the gene of interest with downstream tags.

3. C-terminal Fusion Purification Tags:

   • Myc Epitope Tag: Facilitates rapid Western Blot tracking, immuno-precipitation (IP), and co-IP screening protocols via anti-Myc monoclonal antibodies.

   • Polyhistidine (6xHis) Tag: Positioned at the extreme C-terminus to permit high-purity, one-step purification via Immobilized Metal Affinity Chromatography (IMAC) matrices like Ni-NTA resins.

4. 3' AOX1 Transcription Terminator: Provides essential, efficient mRNA polyadenylation processing signals and precise transcription stop sites to maintain heterologous mRNA stability and translation efficiency.

5. Genomic Integration Mechanism: Prior to transforming Pichia protoplasts or competent cells, the circular vector must undergo complete single-site linearization using unique restriction enzymes (such as BstXI or PmeI) located within the 5' AOX1 promoter sequence. Homologous recombination coordinates the integration of the linear cassette into the host chromosomal AOX1 locus as single or tandem multi-copy arrays.

III Plasmid Propagation, Transformation, and Selection Protocols

1. Bacterial Plasmid Propagation:

   • Recommended Hosts: E. coli TOP10, DH5alpha, or equivalent standard cloning-grade competent cells.

   • Selection Broth Formula: Must use Low Salt LB medium (Low Salt LB broth/agar: 10 g tryptone, 5 g yeast extract, 5 g NaCl per liter, adjusted to pH 7.5). Note: Blasticidin activity is heavily inhibited by high ionic strength; standard high-salt LB recipes will fail to select properly.

   • Antibiotic Working Concentration: Supplement media with 50 μg/ml to 100 μg/ml of Blasticidin for bacterial selection. Culture at 37 degrees Celsius overnight before performing standard plasmid midi- or maxi-preps.

2. Yeast Transformation and Clone Selection:

   • Common Pichia pastoris Strains: GS115 (His4- mutant), KM71H, X-33, and related strains.

   • Linearization Step: Digest the purified plasmid with a unique restriction enzyme inside the 5' AOX1 region. Verify complete linearization via agarose gel electrophoresis, extract with phenol-chloroform or clean with a column system, and resuspend in sterile deionized water.

   • Electroporation Execution: Prepare electrocompetent Pichia pastoris cells. Combine 5-10 μg of the linearized DNA with 80 μl of competent cells, and transfer into a pre-chilled 0.2 cm electroporation cuvette. Pulse using standard yeast parameters (e.g., 1.5 kV, 25 μF, 200 Ω).

   • Outgrowth and Plate Selection: Immediately quench the shocked mixture with 1 ml of ice-cold 1 M Sorbitol solution. Resuspend gently and incubate statically at 30 degrees Celsius for 1 to 2 hours for phenotypic recovery. Plate the slurry onto YPD agar plates supplemented with 100 μg/ml to 300 μg/ml Blasticidin, and incubate at 30 degrees Celsius for 3 to 5 days until positive transformant colonies emerge.

IV Strategic Research Applications

1. Methanol-Inducible Intracellular Production of Recombinant Proteins: As pPIC6 lacks an N-terminal secretion signal peptide sequence, the expressed target accumulates directly within the Pichia cytoplasm. It is widely leveraged for the large-scale production of functional enzymes, structural proteins, and soluble cytokines that do not require complex secretory glycosylation but tend to form insoluble inclusion bodies when expressed in E. coli.

2. Rapid High-Antibiotic Screening for Multi-copy Integrants: By systematically raising selection pressures on YPD plates (e.g., from 300 μg/ml up to 1000 μg/ml or higher Blasticidin levels), investigators can directly enrich hyper-expressing clones carrying tandem multi-copy integration cassettes within their genome, maximizing overall production yields.

3. Protein Modification and Interactome Mapping via Dual Tags: Utilizing the built-in C-terminal Myc and 6xHis fusion framework, the target protein can be purified through affinity chromatography and directly deployed in downstream biochemical assays. These include pull-down assays, intracellular localization tracing via confocal microscopy, and downstream mass spectrometry characterizations.

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