Glycine Cleavage System and cAMP Receptor Protein Co-Regulate CRISPR/cas3 Expression to Resist Bacteriophage
Glycine Cleavage System and cAMP Receptor Protein Co-Regulate CRISPR/cas3 Expression to Resist Bacteriophage
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甘氨酸裂解系统和 cAMP 受体蛋白共同调节 CRISPR/cas3 表达以抵抗噬菌体
DOI：
10.3390/v12010090
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发表时间：
2020-01-01
期刊：
影响因子：
4.7
通讯作者：
Sun, Jianhe
中科院分区：
文献类型：
--
作者：
Yang, Denghui;Wang, Zhaofei;Sun, Jianhe
CRISPR/Cas系统通过一种复杂的机制保护细菌免受噬菌体和质粒的侵袭，其中Cas操纵子由cse1和Cas3组成。然而，对I-E型CRISPR/Cas系统中Cas3操纵子调控的全面研究还很少。在此，我们研究了Cas3在大肠杆菌中的调控。当CRISPR/Cas系统的CasA操纵子被激活时，gcvP或CRP突变降低了CRISPR/Cas系统的干扰能力，增加了细菌对噬菌体的敏感性。由gcvTHP操纵子编码的甘氨酸裂解系统(GCS)的沉默降低了Cas3的表达。加入GCS催化甘氨酸的产物N5，N10-亚甲基四氢叶酸(N5，N10-MTHF)可以激活Cas3的表达。此外，cAMP受体蛋白(CRP)编码的cAMP受体蛋白(CRP)通过与Cas3启动子结合来激活Cas3的表达以响应cAMP浓度。由于N5，N10-MTHF为嘌呤提供了一个碳单位，我们推测GCS通过与CRP结合来调节Cas3。可见gcvP基因突变并不能进一步降低CAS3的表达，同时伴随着CRP的缺失。这些结果说明了一种新的调控途径，即GCS和CRP共同调节CRISPR/Cas系统的Cas3，并有助于防御侵袭性遗传因素，其中CRP是GCS调节Cas3表达所必需的。
The CRISPR/Cas system protects bacteria against bacteriophage and plasmids through a sophisticated mechanism where cas operon plays a crucial role consisting of cse1 and cas3. However, comprehensive studies on the regulation of cas3 operon of the Type I-E CRISPR/Cas system are scarce. Herein, we investigated the regulation of cas3 in Escherichia coli. The mutation in gcvP or crp reduced the CRISPR/Cas system interference ability and increased bacterial susceptibility to phage, when the casA operon of the CRISPR/Cas system was activated. The silence of the glycine cleavage system (GCS) encoded by gcvTHP operon reduced cas3 expression. Adding N5, N10-methylene tetrahydrofolate (N5, N10-mTHF), which is the product of GCS-catalyzed glycine, was able to activate cas3 expression. In addition, a cAMP receptor protein (CRP) encoded by crp activated cas3 expression via binding to the cas3 promoter in response to cAMP concentration. Since N5, N10-mTHF provides one-carbon unit for purine, we assumed GCS regulates cas3 through associating with CRP. It was evident that the mutation of gcvP failed to further reduce the cas3 expression with the crp deletion. These results illustrated a novel regulatory pathway which GCS and CRP co-regulate cas3 of the CRISPR/Cas system and contribute to the defence against invasive genetic elements, where CRP is indispensable for GCS regulation of cas3 expression.