A method for identifying the location and phasing of modified cytosines (C) in long stretches of nucleic acids is provided. In some embodiments, the method may comprise (a) reacting a first portion of a nucleic acid sample containing at least one C and/or at least one modified C with a DNA glucosyltransferase and a cytidine deaminase to produce a first product and optionally reacting a second portion of the sample with a dioxygenase and a cytidine deaminase to produce a second product and; (b) comparing the sequences from the first and optionally the second product obtained in (a), or amplification products thereof, with each other and/or an untreated reference sequence to determine which Cs in the initial nucleic acid fragment are modified. A modified TET methylcytosine dioxygenase that is more efficient at converting methylcytosine to carboxymethylcytosine is also provided.
本研究提供了一种用于鉴定长链核酸中修饰
胞嘧啶(C)的位置和相位的方法。在一些实施方案中,该方法可包括 (a) 将含有至少一个 C 和/或至少一个修饰 C 的核酸样本的第一部分与 DNA
葡糖基转移酶和
胞苷脱
氨酶反应,以产生第一产物,并选择性地将样本的第二部分与二氧酶和
胞苷脱
氨酶反应,以产生第二产物,以及;(b) 将(a)中获得的第一和第二产物或其扩增产物的序列相互比较和/或与未经处理的参考序列比较,以确定初始核酸片段中哪些 Cs 被修饰。还提供了一种修饰的 TET 甲基
胞嘧啶二氧 化酶,它能更有效地将甲基
胞嘧啶转化为羧甲基
胞嘧啶。