Fallah Mahnaz Shafaei, Mohebbi Alireza, Yasaghi Mohammad, Ghaemi Ezzat Allah
Student Research Committee, Golestan University of Medical Sciences, 4934174515 Gorgan, Iran.
Department of Microbiology, Golestan University of Medical Sciences, 4918936316 Gorgan, Iran.
Infect Genet Evol. 2021 Aug;92:104881. doi: 10.1016/j.meegid.2021.104881. Epub 2021 Apr 24.
The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is a bacterial defense mechanism against bacteriophages composed of two different parts: the CRISPR array and the Cas genes. The spacer acquisition is done by the adaptation module consisting of the hallmark Cas1 Cas2 proteins, which inserts new spacers into the CRISPR array. Here we aimed to describe the CRISPR-Cas system in Proteus mirabilis (P. mirabilis) isolates. CRISPR loci was observed in 30 genomic contents of 109 P. mirabilis isolates that each locus was consisted of two CRISPR arrays and each array had a different preserved leader sequences. Only the type I-E CRISPR-Cas system was common in these isolates. The source of the spacers was identified, including phages and prophages. CRISPR spacer origin analysis also identified a conserved PAM sequence of 5'-AAG-3' nucleotide stretch. Through collecting spacers, CRISPR arrays of P. mirabilis isolates were expanded mostly by integration of bacteriophageal source of spacers. This study shows novel findings in the area of the P-mirabilis CRISPR-Cas system. In this regard, among analyzed genome of P. mirabilis isolates, Class I CRISR-Cas systems were dominant, and all belonged to type I-E. In the flanks of the CRISPR, some other elements with regulatory role were also found. A motif of 11 nt size was found to be preserved among the analyzed genome. We believe that it might has a CRISPR-Cas system transcription facilitator by targeting the Rho element.
成簇规律间隔短回文重复序列（CRISPR）是细菌对抗噬菌体的一种防御机制，由两个不同部分组成：CRISPR阵列和Cas基因。间隔序列的获取由由标志性的Cas1和Cas2蛋白组成的适应模块完成，该模块将新的间隔序列插入CRISPR阵列。在这里，我们旨在描述奇异变形杆菌（P. mirabilis）分离株中的CRISPR-Cas系统。在109株奇异变形杆菌分离株的30个基因组内容物中观察到CRISPR位点，每个位点由两个CRISPR阵列组成，每个阵列具有不同的保守前导序列。在这些分离株中，只有I-E型CRISPR-Cas系统是常见的。确定了间隔序列的来源，包括噬菌体和原噬菌体。CRISPR间隔序列起源分析还确定了一个保守的5'-AAG-3'核苷酸延伸的PAM序列。通过收集间隔序列，奇异变形杆菌分离株的CRISPR阵列主要通过整合噬菌体来源的间隔序列而扩展。这项研究在奇异变形杆菌CRISPR-Cas系统领域显示了新的发现。在这方面，在分析的奇异变形杆菌分离株基因组中，I类CRISR-Cas系统占主导地位，并且都属于I-E型。在CRISPR的侧翼，还发现了一些具有调节作用的其他元件。在分析的基因组中发现了一个11 nt大小的基序是保守的。我们认为它可能通过靶向Rho元件而具有CRISPR-Cas系统转录促进因子的作用。
