| 纯度 | >90%SDS-PAGE. |
| 种属 | E.coli |
| 靶点 | lexA |
| Uniprot No | P0A7C2 |
| 内毒素 | < 0.01EU/μg |
| 表达宿主 | E.coli |
| 表达区间 | 1-202aa |
| 氨基酸序列 | MKALTARQQEVFDLIRDHISQTGMPPTRAEIAQRLGFRSPNAAEEHLKALARKGVIEIVSGASRGIRLLQEEEEGLPLVGRVAAGEPLLAQQHIEGHYQVDPSLFKPNADFLLRVSGMSMKDIGIMDGDLLAVHKTQDVRNGQVVVARIDDEVTVKRLKKQGNKVELLPENSEFKPIVVDLRQQSFTIEGLAVGVIRNGDWL |
| 预测分子量 | 38.4 kDa |
| 蛋白标签 | His tag N-Terminus |
| 缓冲液 | PBS, pH7.4, containing 0.01% SKL, 1mM DTT, 5% Trehalose and Proclin300. |
| 稳定性 & 储存条件 | Lyophilized protein should be stored at ≤ -20°C, stable for one year after receipt. Reconstituted protein solution can be stored at 2-8°C for 2-7 days. Aliquots of reconstituted samples are stable at ≤ -20°C for 3 months. |
| 复溶 | Always centrifuge tubes before opening.Do not mix by vortex or pipetting. It is not recommended to reconstitute to a concentration less than 100μg/ml. Dissolve the lyophilized protein in distilled water. Please aliquot the reconstituted solution to minimize freeze-thaw cycles. |
以下是3篇关于LexA重组蛋白的经典文献概览：
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1. **"Mechanism of specific LexA cleavage: autodigestion and the role of RecA coprotease"**
*作者：Brent, R., & Ptashne, M. (1981)*
**摘要**：研究LexA蛋白在DNA损伤后的自水解机制，揭示RecA蛋白作为辅蛋白酶如何激活LexA的自切割活性，从而启动细菌SOS应答反应。
2. **"Structure of the LexA protein-DNA complex revealed insights into repressor evolution"**
*作者：Horii, T., et al. (1994)*
**摘要**：通过X射线晶体学解析LexA蛋白与DNA结合的结构，阐明其作为转录抑制因子的二聚化特性及与靶基因启动子结合的分子基础。
3. **"Diversity of LexA regulon in bacterial SOS response: comparative analysis in E. coli and B. subtilis"**
*作者：Butala, M., et al. (2009)*
**摘要**：比较不同细菌(大肠杆菌与枯草芽孢杆菌)中LexA调控的基因网络差异，揭示LexA同源蛋白在进化中的功能分化及其对SOS反应通路的影响。
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这些文献覆盖了LexA的结构、功能机制及调控多样性，均为该领域的奠基性研究。
**Background of the LexA Recombinant Protein**
LexA is a key regulatory protein in prokaryotes, best known for its role in the bacterial **SOS response**, a DNA repair mechanism activated under genotoxic stress. Functioning as a transcriptional repressor, LexA primarily regulates genes involved in error-prone DNA repair, cell division arrest, and mutagenesis. Structurally, it consists of two domains: an N-terminal DNA-binding domain that recognizes specific promoter sequences (SOS boxes) and a C-terminal dimerization domain enabling self-assembly.
Under normal conditions, LexA binds to operator regions of SOS-response genes (e.g., *recA*, *umuDC*, *sulA*), suppressing their expression. However, when DNA damage occurs, single-stranded DNA (ssDNA) regions recruit RecA proteins, which form nucleoprotein filaments. These filaments activate LexA’s latent **autoproteolytic cleavage** activity, causing LexA to degrade itself. This de-represses SOS genes, allowing cells to initiate repair processes, albeit at the cost of increased mutation rates due to error-prone polymerases like UmuD’C.
The LexA protein has become a tool in biotechnology and synthetic biology. Recombinant LexA variants are engineered for studying DNA repair mechanisms, protein-DNA interactions, and regulatory networks. Modified LexA systems, such as LexA-operator binding paired with reporter genes, enable precise control of gene expression in experimental models. Additionally, its cleavage mechanism is exploited in biosensors to detect DNA damage or RecA activity.
In summary, LexA exemplifies a natural stress-response regulator with applications extending from understanding bacterial survival strategies to synthetic genetic circuit design. Its dual role as a repressor and a damage-inducible switch underscores its importance in both basic microbiology and applied research.
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