Molecular mechanisms of III-B CRISPR–Cas systems in archaea
Molecular mechanisms of III-B CRISPR–Cas systems in archaea
复制标题
古细菌 III-B CRISPR-Cas 系统的分子机制
DOI：
10.1042/etls20180023
复制
发表时间：
2018
影响因子：
3.8
通讯作者：
Qunxin She
中科院分区：
文献类型：
--
作者：
Yan Zhang;Jinzhong Lin;Mingxia Feng;Qunxin She
Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-asso-.ciated (Cas) systems provide the adaptive antiviral immunity against invasive genetic ele-.ments in archaea and bacteria. These immune systems are divided into at least six.different types, among which Type III CRISPR – Cas systems show several distinct antiviral.activities as demonstrated from the investigation of bacterial III-A and archaeal III-B.systems in the past decade. First, although initial experiments suggested that III-A.systems provided DNA interference activity, whereas III-B system was active only in RNA.interference, these immune systems were subsequently found to mediate the transcrip-.tion-dependent DNA interference and the dual DNA/RNA interference. Second, their.ribonucleoprotein (RNP) complexes show target RNA (tgRNA) cleavage by a ruler mech-.anism and RNA-activated indiscriminate single-stranded DNA cleavage, the latter of.which is subjected to spatiotemporal regulation such that the DNase activity occurs only.at the right place in the right time. Third, RNPs of Type III systems catalyse the synthe-.sis of cyclic oligoadenylates (cOAs) that function as second messengers to activate.Csm6 and Csx1, both of which are potent Cas accessory RNases after activation. To.date, Type III CRISPR systems are the only known antiviral immunity that utilizes multiple.interference mechanisms for antiviral defence.
