CRISPR-Cas systems in multicellular cyanobacteria
CRISPR-Cas systems in multicellular cyanobacteria
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DOI：
10.1080/15476286.2018.1493330
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发表时间：
2019-04-03
期刊：
影响因子：
4.1
通讯作者：
Hess, Wolfgang R.
中科院分区：
文献类型：
--
作者：
Hou, Shengwei;Brenes-Alvarez, Manuel;Hess, Wolfgang R.
新型CRISPR-Cas系统具有基因组编辑和基因表达操纵的巨大潜力。CRISPR-Cas系统的类型和数量在不同生物体之间有很大差异。一些丝状蓝细菌具有> 40种不同的推定CRISPR重复间隔区盒，而cas基因实例的数量要低得多。在这里，我们讨论了CRISPR-Cas系统和CRISPR样重复间隔区阵列在171个公开的多细胞蓝藻基因组中的类型和多样性。1328个重复间隔区阵列的数量超过了391个编码的Cas 1蛋白的总数，这表明了片段化的趋势或替代适应因子的参与。模式蓝细菌鱼腥藻PCC 7120仅包含3个cas 1基因，但拥有3个1类、可能1个2类和5个孤儿重复间隔区阵列，所有这些都表现出典型的crRNA表达模式，表明活跃的转录、成熟和掺入CRISPR复合物。中断鱼腥藻属PCC 7120 fdxN基因的元件内的CRISPR-Cas系统以及其他菌株中的类似排列占据了在分化相关的程序化位点特异性重组期间被切除的遗传元件。这一事实表明这些元素与CRISPR-cas系统整合的倾向，并指出了以前未认识到的联系。类似于可能的2类效应蛋白的基因all 3613与短重复间隔区阵列和单个tRNA基因相连，类似于其在其他蓝藻中的同源物。DNA元件中许多CRISPR-Cas系统的多样性和存在使丝状蓝藻成为其研究的丰富资源。
Novel CRISPR-Cas systems possess substantial potential for genome editing and manipulation of gene expression. The types and numbers of CRISPR-Cas systems vary substantially between different organisms. Some filamentous cyanobacteria harbor > 40 different putative CRISPR repeat-spacer cassettes, while the number of cas gene instances is much lower. Here we addressed the types and diversity of CRISPR-Cas systems and of CRISPR-like repeat-spacer arrays in 171 publicly available genomes of multicellular cyanobacteria. The number of 1328 repeat-spacer arrays exceeded the total of 391 encoded Cas1 proteins suggesting a tendency for fragmentation or the involvement of alternative adaptation factors. The model cyanobacterium Anabaena sp. PCC 7120 contains only three cas1 genes but hosts three Class 1, possibly one Class 2 and five orphan repeat-spacer arrays, all of which exhibit crRNA-typical expression patterns suggesting active transcription, maturation and incorporation into CRISPR complexes. The CRISPR-Cas system within the element interrupting the Anabaena sp. PCC 7120 fdxN gene, as well as analogous arrangements in other strains, occupy the genetic elements that become excised during the differentiation-related programmed site-specific recombination. This fact indicates the propensity of these elements for the integration of CRISPR-cas systems and points to a previously not recognized connection. The gene all3613 resembling a possible Class 2 effector protein is linked to a short repeat-spacer array and a single tRNA gene, similar to its homologs in other cyanobacteria. The diversity and presence of numerous CRISPR-Cas systems in DNA elements that are programmed for homologous recombination make filamentous cyanobacteria a prolific resource for their study.