Mobile element warfare via CRISPR and anti-CRISPR in Pseudomonas aeruginosa.
Mobile element warfare via CRISPR and anti-CRISPR in Pseudomonas aeruginosa.
复制标题
铜绿假单胞菌中通过 CRISPR 和抗 CRISPR 进行的移动元素战。
DOI：
10.1093/nar/gkab006
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发表时间：
2021-02-26
影响因子：
14.9
通讯作者：
Bondy-Denomy J
中科院分区：
文献类型：
--
作者：
León LM;Park AE;Borges AL;Zhang JY;Bondy-Denomy J
细菌部署多重防御以防止移动的遗传元件（MGE）入侵。CRISPR-Cas免疫系统使用RNA引导的核酸酶来靶向MGE，MGE与抗CRISPR（Acr）蛋白对抗。我们对常见的I-C型CRISPR-Cas亚型的生物学和共同进化动力学的理解已经滞后，因为它缺乏体内噬菌体-宿主模型系统。在这里，我们展示了在接合pKLC 102岛上编码的铜绿假单胞菌I-C型CRISPR-Cas系统的抗噬菌体功能，以及不同MGE对其Acr介导的抑制作用。鉴定了7个具有抗I-C型功能的基因（acrIC基因），许多具有高酸性氨基酸含量，包括先前描述的DNA模拟物AcrIF 2。其中四个acr基因是广谱的，也抑制I-E或I-F铜绿假单胞菌CRISPR-Cas亚型。然而，双重抑制是有代价的，因为I-C和I-F型系统的同时表达使得表达双重抑制剂AcrIF 2的cDNA对靶向更敏感。AcrIF 2中许多酸性残基的突变本身并不损害抗I-C或抗I-F功能，但在竞争过程中确实加剧了抑制缺陷，这表明过量的负电荷可能缓冲DNA模拟物对抗竞争。像AcrIF 2一样，五种Acr蛋白阻止Cascade结合DNA，而两种蛋白在下游发挥作用，可能阻止Cas 3的募集或活性。一种这样的抑制剂AcrIC 3被发现在缀合元件内的“抗Cas 3”簇中，与真正的Cas 3抑制剂AcrIF 3和AcrIE 1一起编码。我们的研究结果证明了MGE编码的CRISPR-Cas系统与其不同的MGE靶标之间的积极斗争。
Bacteria deploy multiple defenses to prevent mobile genetic element (MGEs) invasion. CRISPR–Cas immune systems use RNA-guided nucleases to target MGEs, which counter with anti-CRISPR (Acr) proteins. Our understanding of the biology and co-evolutionary dynamics of the common Type I-C CRISPR–Cas subtype has lagged because it lacks an in vivo phage-host model system. Here, we show the anti-phage function of a Pseudomonas aeruginosa Type I-C CRISPR–Cas system encoded on a conjugative pKLC102 island, and its Acr-mediated inhibition by distinct MGEs. Seven genes with anti-Type I-C function (acrIC genes) were identified, many with highly acidic amino acid content, including previously described DNA mimic AcrIF2. Four of the acr genes were broad spectrum, also inhibiting I-E or I-F P. aeruginosa CRISPR–Cas subtypes. Dual inhibition comes at a cost, however, as simultaneous expression of Type I-C and I-F systems renders phages expressing the dual inhibitor AcrIF2 more sensitive to targeting. Mutagenesis of numerous acidic residues in AcrIF2 did not impair anti-I-C or anti-I-F function per se but did exacerbate inhibition defects during competition, suggesting that excess negative charge may buffer DNA mimics against competition. Like AcrIF2, five of the Acr proteins block Cascade from binding DNA, while two function downstream, likely preventing Cas3 recruitment or activity. One such inhibitor, AcrIC3, is found in an ‘anti-Cas3’ cluster within conjugative elements, encoded alongside bona fide Cas3 inhibitors AcrIF3 and AcrIE1. Our findings demonstrate an active battle between an MGE-encoded CRISPR–Cas system and its diverse MGE targets.
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影响因子：
16
作者：
Leenay RT;Maksimchuk KR;Slotkowski RA;Agrawal RN;Gomaa AA;Briner AE;Barrangou R;Beisel CL
通讯作者：
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14.9
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