Human activation-induced deaminase lacks strong replicative strand bias or preference for cytosines in hairpin loops.
Human activation-induced deaminase lacks strong replicative strand bias or preference for cytosines in hairpin loops.
复制标题
DOI：
10.1093/nar/gkac296
复制
发表时间：
2022-05-20
影响因子：
14.9
通讯作者：
Bhagwat, Ashok S.
中科院分区：
文献类型：
--
作者：
Sakhtemani, Ramin;Perera, Madusha L. W.;Huebschmann, Daniel;Siebert, Reiner;Lawrence, Michael S.;Bhagwat, Ashok S.
激活诱导的脱氨酶（AID）是DNA-胞嘧啶脱氨酶，其通过体细胞超突变和类别转换重组介导抗体的成熟。虽然它会导致免疫球蛋白重链和轻链基因的突变以及免疫球蛋白重链基因开关区的链断裂，但它在很大程度上避免了在基因组的其余部分造成这种损伤。为了帮助理解人类AID的靶向作用，我们在修复缺陷型大肠杆菌中表达了它，并使用尿嘧啶下拉和测序（EST-seq）在基因组DNA中绘制了所产生的尿嘧啶。我们发现AID和人APOBEC 3A都优先靶向tRNA基因和转录起始位点，但对高度转录的基因没有表现出偏好。与A3 A不同，AID没有表现出强烈的复制链偏好或对发夹环的偏好。这些酶之间重叠的尿嘧啶化峰含有一种蛋白质FIS的结合位点，该蛋白质FIS有助于在E. coli基因组。为了证实这些发现是否与B细胞相关，我们检测了来自淋巴瘤和白血病基因组中AIDS偏好序列的突变。这些突变也缺乏复制链偏好或发夹环偏好。我们在这里提出了一个模型，艾滋病如何避免引起突变的单链DNA复制叉内发现。人类AID对发夹环中的胞嘧啶缺乏偏好，这阻止了它在复制叉处起作用。
Activation-induced deaminase (AID) is a DNA-cytosine deaminase that mediates maturation of antibodies through somatic hypermutation and class-switch recombination. While it causes mutations in immunoglobulin heavy and light chain genes and strand breaks in the switch regions of the immunoglobulin heavy chain gene, it largely avoids causing such damage in the rest of the genome. To help understand targeting by human AID, we expressed it in repair-deficient Escherichia coli and mapped the created uracils in the genomic DNA using uracil pull-down and sequencing, UPD-seq. We found that both AID and the human APOBEC3A preferentially target tRNA genes and transcription start sites, but do not show preference for highly transcribed genes. Unlike A3A, AID did not show a strong replicative strand bias or a preference for hairpin loops. Overlapping uracilation peaks between these enzymes contained binding sites for a protein, FIS, that helps create topological domains in the E. coli genome. To confirm whether these findings were relevant to B cells, we examined mutations from lymphoma and leukemia genomes within AID-preferred sequences. These mutations also lacked replicative strand bias or a hairpin loop preference. We propose here a model for how AID avoids causing mutations in the single-stranded DNA found within replication forks. The lack of preference of human AID for cytosines in hairpin loops prevents it from acting at replication forks.
登录
查看更多内容
影响因子：
64.5
作者：
Haradhvala NJ;Polak P;Stojanov P;Covington KR;Shinbrot E;Hess JM;Rheinbay E;Kim J;Maruvka YE;Braunstein LZ;Kamburov A;Hanawalt PC;Wheeler DA;Koren A;Lawrence MS;Getz G
通讯作者：
Getz G
影响因子：
4.8
作者：
Branton，Sarah A.;Ghorbani，Atefeh;Larijani，Mani
通讯作者：
Larijani，Mani
影响因子：
20.3
作者：
Greeve, J;Philipsen, A;Parwaresch, R
通讯作者：
Parwaresch, R
影响因子：
4.8
作者：
Canugovi, Chandrika;Samaranayake, Mala;Bhagwat, Ashok S.
通讯作者：
Bhagwat, Ashok S.
影响因子：
8
作者：
Duquette, ML;Pham, P;Maizels, N
通讯作者：
Maizels, N