Yu Kefei, Huang Feng-Ting, Lieber Michael R
University of Southern California Norris Comprehensive Cancer Center, Department of Pathology, Los Angeles, California 90089, USA.
J Biol Chem. 2004 Feb 20;279(8):6496-500. doi: 10.1074/jbc.M311616200. Epub 2003 Nov 25.
Activation-induced deaminase (AID) is required for both immunoglobulin class switch recombination and somatic hypermutation. AID is known to deaminate cytidines in single-stranded DNA, but the relationship of this step to the class switch or somatic hypermutation processes is not entirely clear. We have studied the activity of a recombinant form of the mouse AID protein that was purified from a baculovirus expression system. We find that the length of the single-stranded DNA target is critical to the action of AID at the Cs positioned anywhere along the length of the DNA. The DNA sequence surrounding a given C influences AID deamination efficiency. AID preferentially deaminates Cs in the WRC motif, and additionally has a small but consistent preference for purine at the position after the WRC, thereby favoring WRCr (the lowercase r corresponds to the smaller impact on activity).
激活诱导的脱氨酶（AID）对于免疫球蛋白类别转换重组和体细胞超突变都是必需的。已知AID可使单链DNA中的胞嘧啶脱氨基，但这一步骤与类别转换或体细胞超突变过程之间的关系尚不完全清楚。我们研究了从小鼠杆状病毒表达系统中纯化的重组形式小鼠AID蛋白的活性。我们发现，单链DNA靶标的长度对于AID在DNA长度上任何位置的胞嘧啶处的作用至关重要。给定胞嘧啶周围的DNA序列会影响AID的脱氨基效率。AID优先使WRC基序中的胞嘧啶脱氨基，并且在WRC之后的位置对嘌呤也有小但一致的偏好，从而有利于WRCr（小写字母r表示对活性的影响较小）。
