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phi29 DNA Polymerase

Company: New England Biolabs
Catalog#: M0269S
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Coupling Exonuclease Digestion with Selective Chemical Labeling for Base-resolution Mapping of 5-Hydroxymethylcytosine in Genomic DNA
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Date:
2018-03-05
[Abstract]  This protocol is designed to obtain base-resolution information on the level of 5-hydroxymethylcytosine (5hmC) in CpGs without the need for bisulfite modification. It relies on (i) the capture of hydroxymethylated sequences by a procedure known as ‘selective chemical labeling’ (see Szulwach et al., 2012) and (ii) the digestion of the captured DNA by exonucleases. After Illumina sequencing of the digested DNA fragments, an ad hoc bioinformatic pipeline extracts the information for further downstream analysis. [摘要]  该协议旨在获得CpGs中5-羟甲基胞嘧啶(5hmC)水平的碱基分辨率信息,而无需亚硫酸氢盐修饰。 它依赖于(i)通过称为“选择性化学标记”(参见Szulwach等人,2012)的方法捕获羟甲基化序列和(ii)通过外切核酸酶消化捕获的DNA。 在消化的DNA片段的Illumina测序之后,特设的生物信息学管道提取信息用于进一步的下游分析。

【背景】基因组DNA中胞嘧啶的甲基化可以被蛋白质读取,并且主要被翻译成基因沉默。基因组中的大多数CpG二核苷酸是甲基化的,包括位于基因调控区如增强子的那些。然而,当需要时,这些CpG可以通过Ten Eleven Translocation(TET)酶将甲基氧化并且通过碱基切除修复系统用未甲基化的胞嘧啶置换来去甲基化。 5-羟甲基胞嘧啶(5hmC)是5-甲基胞嘧啶的第一个氧化衍生物,并且在基因组中绘制该修饰的碱基提供了关于正在进行活性去甲基化的区域的信息。尽管选择性化学标记(SCL)可以非常特异地检测5hmC,但该技术的分辨率受DNA片段大小的限制,特别是当捕获的DNA中存在多个CpG时。为了提高分辨率,我们引入了使用外切核酸酶的消化步骤,所述核酸外切酶将DNA分子修剪成靠近羟甲基化的胞嘧啶(Sérandour et。,2016)。然后对测序读数进行适当的生物信息学处理,然后将羟甲基化评分赋予捕获的CpG。

In vitro Assays for Eukaryotic Leading/Lagging Strand DNA Replication
Author:
Date:
2017-09-20
[Abstract]  The eukaryotic replisome is a multiprotein complex that duplicates DNA. The replisome is sculpted to couple continuous leading strand synthesis with discontinuous lagging strand synthesis, primarily carried out by DNA polymerases ε and δ, respectively, along with helicases, polymerase α-primase, DNA sliding clamps, clamp loaders and many other proteins. We have previously established the mechanisms by which the polymerases ε and δ are targeted to their ‘correct’ strands, as well as quality control mechanisms that evict polymerases when they associate with an ‘incorrect’ strand. Here, we provide a practical guide to differentially assay leading and lagging strand replication in vitro using pure proteins. [摘要]  真核生物复制品是重复DNA的多蛋白复合物。 复制品被雕刻成连续的前导链合成与不连续的滞后链合成,主要通过DNA聚合酶ε和δ以及解旋酶,聚合酶α-引发酶,DNA滑动夹,夹带载体和许多其它蛋白质进行。 我们以前已经建立了聚合酶ε和δ靶向其“正确”链的机制,以及在与“不正确”链相关联时驱赶聚合酶的质量控制机制。 在这里,我们提供了使用纯蛋白质在体外差异测定前导和滞后链复制的实用指南。
Using pure proteins from Saccharomyces cerevisiae, our lab was the first to reconstitute a functional eukaryotic DNA replisome, a ~2 MDa complex that includes the 11-subunit CMG helicase (complex of Cdc45, Mcm2-7, GINS heterotetramer), the 4-subunit DNA polymerase (Pol) ε, the 4-subunit Pol α-primase, the PCNA (Proliferating Cell Nuclear Antigen) clamp homotrimer ring shaped processivity factor that ...

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