
Background
The IS Detection kit is designed to test for the presence of transposable Insertion Sequences (IS) in a DNA of interest. IS elements are naturally present in the genomes of E. coli strains commonly used for protein and plasmid production. IS element transposition is known to be stimulated by the cell stress response and can lead to IS element “hopping” into plasmid DNA and or into other regions of the chromosome. Factors such the production of foreign proteins or the burden of carrying a high copy plasmid can induce the cell stress response. To alleviate these undesired transposition events, Scarab Genomics produced the Clean Genome® E. coli strains. These strains are devoid of all known IS elements (1-3) thereby creating the ideal hosts for the production of foreign proteins or plasmid DNA. This kit can be used to detect for the presence of all the specific known IS elements in the genomes of commonly used E. coli strains (Figure 1). It can also be used to determine which elements may have transposed into a plasmid grown in these strains. The kit also detects the presence or absence of known recombination hot spots (Rhs) in the E. coli genome.
Figures
Figure 1: IS Elements in popular E. coli strains. Each box shows the number of copies of the element in the genome. Note: these counts represent a snapshot in time. Strains that have been sub-cultured multiple times may differ in their IS count or contain different complements of IS elements. *Subsequent to the commercialization of the Clean Genome® E. coli strains, 2 copies of an atypical IS element named IS609 were recognized in the E. coli O157:H7 genome sequence (4). This IS element has not been shown to transpose, although other members of this IS family have been shown to transpose. The ability to transpose requires an intact orfA. The single IS609 element found in E. coli K-12 and B strains, however, carries a defective orfA with a stop codon mutation located near the middle of the ORF. IS609 has been removed in derivatives of the original MDS™ strains, indicated as “MDS™42 ΔMD64”.
Figure 2. Detection of IS Elements in Plasmid Obtained from Commercial Sources. Detection of IS contamination in a commercial plasmid preparation of pBR322. Inward primers (panels a-d) or outward primers (panels e-h) specific for IS1, IS2, IS3, IS5, IS10, and IS186 were used (lanes 1-6, respectively; M is 1 kb+ size standard). Panels a and e show negative controls (no DNA), while positive controls in panels b and f are the individual IS elements cloned into pBR322. Panels c and g show purchased pBR322 and panels d and h show pBR322 isolated from MDS™42. PCR amplimers generated with outward primers specific for IS1, IS2, IS3, IS5, IS10 and IS186 were ligated, cloned with selection for tetracycline or ampicillin resistance, and sequenced (data not shown). Sequencing confirmed transposition of IS1, IS2, IS5, and IS10 to pBR322 in the commercial preparation.
Figure 3. Workflow for pDNA production in Clean Genome® and unreduced E. coli strains. Extra care in the first steps will ensure trouble-free production. A)
B)
Figure 4: IS Primer Validation Using Water in Place of Sample DNA and Positive and Negative Control Genomic DNA. White Glove Kit protocol was followed using water in place of sample DNA. Panel (A) - Six microliters (6 μl) of the PCR amplification product was analyzed on 1.0% 1X TAE agarose gel. No products are visible when water is added in place of template DNA or when using the negative control genomic DNA. Positive control genomic DNA amplify as expected. Panel (B) - Lists the expected size of PCR product to be obtained using the positive and negative control genomic DNA.
Specifications
Kit Components
- Positive Control Genomic DNA: 170 μl, sufficient for the analysis of 10 samples.
- Negative Control Genomic DNA: 170 μl, sufficient for the analysis of 10 samples.
- IS-specific Forward (F) and Reverse (R) Primers: 80 μl of each primer at a concentration of 5μM, sufficient for the analysis of 10 samples.
- Positive Control dnaE Forward Primer and Positive Control dnaE Reverse Primers: 60 μl of each primer at a concentration of 5 μM, sufficient for the analysis of 10 samples.
Forward Primers | Reverse Primer |
IS1 Forward Primer | IS1 Reverse Primer |
IS2 Forward Primer | IS2 Reverse Primer |
IS3/ISEc17 Forward Primer | IS3/ISEc17 Reverse Primer |
IS4 Forward Primer | IS4 Reverse Primer |
IS5 Forward Primer | IS5 Reverse Primer |
IS10 Forward Primer | IS10 Reverse Primer |
IS30D Forward Primer | IS30D Reverse Primer |
IS150 Forward Primer | IS150 Reverse Primer |
IS186 Forward Primer | IS186 Reverse Primer |
IS600/ISsd1 Forward Primer | IS600/ISsd1 Reverse Primer |
IS609 Forward Primer | IS609 Reverse Primer |
IS911 Forward Primer | IS911 Reverse Primer |
ISEc1/3/5 Forward Primer | ISEc1/3/5 Reverse Primer |
ISEc4 Forward Primer | ISEc4 Reverse Primer |
RhsA/B/C Forward Primer | RhsA/B/C Reverse Primer |
RhsD/E Forward Primer | RhsD/E Reverse Primer |
Related Products
MDS™42 Chemically Competent Cell Kit MDS™42 ΔrecA Chemically Competent Cell Kit MDS™42 ΔrecA Blue Chemically Competent Cell Kit MDS™42 Combination Package Chemically Competent Cell Kit ScarabXpress® T7 lac Chemically Competent Cell Kit MDS™42 Electrocompetent Cell Kit MDS™42 ΔrecA Electrocompetent Cell Kit MDS™42 ΔrecA Blue Electrocompetent Cell Kit MDS™42 ΔrecA trfA Electrocompetent Cell Kit MDS™42 ΔrecA trfA Blue Electrocompetent Cell Kit MDS™42 Combination Package Electrocompetent Cell Kit
Support
Product Manuals White Glove IS Detection Kit Reports Production of DNA Vaccines Free from Mobile DNA Papers
- Pósfai G, et al., (2006) Emergent properties of reduced-genome Escherichia coli. Science 312:1044-6.
- Kolisnychenko, V., Plunkett III, G., Herring, C.D., Fehér, T., Pósfai, J., Blattner, F.R., and Pósfai, G. Engineering a reduced Escherichia coli genome. Genome Research 12, 640-647 (2002).
- Sharma, S.S., Blattner, F.R., and Harcum, S.W. Recombinant protein production in an Escherichia coli reduced genome strain. Metabolic Engineering 9, 133-141 (2007).
- Perna, N.T., et al., 2001. Genome sequence of enterohemorrhagic Escherichia coli O157:H7. Nature 409: 529-533 (2001).
Patents & Disclaimers
Scarab is providing you with this Material subject to the non-transferable right to use the subject amount of the Material for your research at your academic institution. The Recipient agrees not to sell or otherwise transfer this Material, or anything derived or produced from the Material to a third party. NO RIGHTS ARE PROVIDED TO USE THE MATERIAL OR ANYTHING DERIVED OR PRODUCED FROM THE MATERIAL FOR COMMERCIAL PURPOSES. If the Recipient makes any changes to the chromosome of the Material that results in an invention in breach of this limited license, then Scarab will have a worldwide, exclusive, royalty-free license to such invention whether patentable or not. If the Recipient is not willing to accept the terms of this limited license, Scarab is willing to accept return of this product with a full refund, minus shipping and handling costs. For information on obtaining a license to this Material for purposes other than research, please contact Scarab’s Licensing Department. Scarab Genomics’ technology is covered by U.S. Pat. No. 6,989,265 and related foreign applications. PHUSION® is a registered trademark of Thermo Fisher Scientific. Plasmid-Safe™ ATP-Dependent DNase is a registered trademark of EPICENTRE® Biotechnologies. Stbl3™ is a trademark of Life Technologies.
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DNA连接酶:可以连接被限制酶切割开磷酸二酯键
产生这一现象的原因在于 DNA合成酶只能沿5'-3'的方向合成DNA 而DNA本身的两条链又是反向分布的 所以就造成了只有一条链合成可以连续地进行下去(以它为模板的子链生成方向正好是DNA聚合酶可以直接提供的) 而后随链要盘绕成回环 反扭过来 才能合成
再合成起始的时候 DNA聚合酶是需要一段RNA引物的 在原核生物中这一引物是由dnaQ(一种酶)在已解旋的单链5'端合成,真核生物中也有对应的酶 由于后随链的合成不连续 所以每个片段都要有引物 在DNA合成结束的时候 这些引物要被切除 因而留下缺口 这时又要特定的酶去填补缺口(比如 大肠杆菌中的DNA聚合酶I)可是填补序列和周围序列间会有缺刻 也就是说他们交界处的3'-5'磷酸二脂键是断开的 这时需要DNA连接酶发挥作用 将其连好
所以 后随链上的缺刻多 还真够DNA连接酶忙一阵的 前导链上只有一开始有RNA引物 因此 最后也基本只有这个地方会用到连接酶
连接酶通常是包括“连接酶”这个字,就如DNA连接酶是将脱氧核糖核酸(DNA)片段连接。其他普遍的名称包括“合成酶”,因为这些酶是用作合成新的分子,或当它们是将二氧化碳加入一个分子时则称为“羧化酶”。
只不过限制性核苷酸酶是将磷酸二酯键切断;而DNA连接酶则是形成磷酸二酯键。
DNA连接酶主要是连接DNA片段之间的磷酸二酯键最初从原核生物(大肠杆菌)分离得到的.现在生物基因工程主要是从T4噬菌体中分离得到的,
酶对所作用的底物有严格的选择性。一种酶仅能作用于一种物质,或一类分子结构相似的物质,促其进行一定的化学反应,产生一定的反应产物,这种选择性作用称为酶的专一性。
有没有人用过NEB的Blunt/TALigaseMasterMix和InstantSticky-endLigaseMasterMix?
有没有人用过NEB的Blunt/TALigaseMasterMix和InstantSticky-endLigaseMasterMix?
有没有人用过NEB的Blunt/TALigaseMasterMix和InstantSticky-endLigaseMasterMix?
.....它说连得又快又好,想问问有木有小白鼠试过它家的这两个产品呢。。如果用过能不能请教下效果咋样呢。。我之前用Thermo的T4,属于又便宜又慢效果还可以的那类型的。。(虽然说thermo也说室温30min就ok,但是还是4度过夜了,室温30min不靠谱)

