Turgeman-Grott Israela, Shalev Yarden, Shemesh Netta, Levy Rachel, Eini Inbar, Pasmanik-Chor Metsada, Gophna Uri
Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
Bioinformatics Unit, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
Microorganisms. 2024 Aug 27;12(9):1772. doi: 10.3390/microorganisms12091772.
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated proteins) systems provide acquired heritable protection to bacteria and archaea against selfish DNA elements, such as viruses. These systems must be tightly regulated because they can capture DNA fragments from foreign selfish elements, and also occasionally from self-chromosomes, resulting in autoimmunity. Most known species from the halophilic archaeal genus contain type I-B CRISPR-Cas systems, and the strongest hotspot for self-spacer acquisition by was a locus that contained a putative transposable element, as well as the gene , which was a very frequent target for self-targeting spacers. To test whether this gene is CRISPR-associated, we investigated it using bioinformatics, deletion, over-expression, and comparative transcriptomics. We show that is a global transcriptional regulator that can repress diverse genes, since its deletion results in significantly higher expression of multiple genes, especially those involved in nutrient transport. When over-expressed, strongly repressed the transcript production of all genes tested, both those involved in spacer acquisition (, and ) and those required for destroying selfish genetic elements ( and ). Considering that is highly conserved in haloarchaea, with homologs that are present in species that do not encode the CRISPR-Cas system, we conclude that it is a global regulator that is also involved in gene regulation, either directly or indirectly.
成簇规律间隔短回文重复序列（CRISPR）-Cas（CRISPR相关蛋白）系统为细菌和古生菌提供了对病毒等自私DNA元件的可遗传的后天保护。这些系统必须受到严格调控，因为它们既能捕获来自外来自私元件的DNA片段，偶尔也会从自身染色体捕获，从而导致自身免疫。嗜盐古菌属的大多数已知物种都含有I-B型CRISPR-Cas系统，并且该属中自我间隔序列获取的最强热点是一个包含推定转座元件以及基因的位点，该基因是自我靶向间隔序列非常频繁的靶点。为了测试该基因是否与CRISPR相关，我们使用生物信息学、缺失、过表达和比较转录组学对其进行了研究。我们发现该基因是一种全局转录调节因子，可抑制多种基因，因为其缺失会导致多个基因，尤其是参与营养物质运输的基因表达显著升高。当过表达时，该基因强烈抑制所有测试基因的转录产物，包括那些参与间隔序列获取的基因（如、和）以及破坏自私遗传元件所需的基因（和）。鉴于该基因在嗜盐古菌中高度保守，在不编码CRISPR-Cas系统的物种中也存在同源物，我们得出结论，它是一种全局调节因子，也直接或间接参与基因调控。
