Hegde Shivanand, Rauch Hallie E, Hughes Grant L, Shariat Nikki
Department of Vector Biology and Tropical Disease Biology, Liverpool School of Tropical Medicine, Centre for Neglected Tropical Disease, Liverpool, UK.
Present address: School of Life Sciences, University of Keele, Newcastle, UK.
Access Microbiol. 2023 Aug 11;5(8). doi: 10.1099/acmi.0.000599.v4. eCollection 2023.
The microbiome profoundly influences many traits in medically relevant vectors such as mosquitoes, and a greater functional understanding of host-microbe interactions may be exploited for novel microbial-based approaches to control mosquito-borne disease. Here, we characterized two novel clustered regularly interspaced short palindromic repeats (CRISPR)/Cas systems in sp. Ag1, which was isolated from the gut of an mosquito. Two distinct CRISPR/Cas systems were identified in Ag1, CRISPR1 and CRISPR2. Based on gene composition, CRISPR1 is classified as a type I-E CRISPR/Cas system and has a single array, CRISPR1. CRISPR2 is a type I-F system with two arrays, CRISPR2.1 and CRISPR2.2. RT-PCR analyses show that all genes from both systems are expressed during logarithmic growth in culture media. The direct repeat sequences of CRISPRs 2.1 and 2.2 are identical and found in the arrays of other spp., including and , whereas CRISPR1 is not. We searched for potential spacer targets and revealed an interesting difference between the two systems: only 9 % of CRISPR1 (type I-E) targets are in phage sequences and 91 % are in plasmid sequences. Conversely, ~66 % of CRISPR2 (type I-F) targets are found within phage genomes. Our results highlight the presence of CRISPR loci in gut-associated bacteria of mosquitoes and indicate interplay between symbionts and invasive mobile genetic elements over evolutionary time.
微生物组对蚊子等医学相关病媒的许多性状具有深远影响，对宿主与微生物相互作用的更深入功能理解可用于开发基于微生物的新型方法来控制蚊媒疾病。在此，我们对从一只蚊子肠道中分离出的sp. Ag1中的两种新型成簇规律间隔短回文重复序列（CRISPR）/Cas系统进行了表征。在Ag1中鉴定出两种不同的CRISPR/Cas系统，即CRISPR1和CRISPR2。基于基因组成，CRISPR1被归类为I-E型CRISPR/Cas系统，有一个单一阵列CRISPR1。CRISPR2是一个I-F型系统，有两个阵列，即CRISPR2.1和CRISPR2.2。逆转录聚合酶链反应（RT-PCR）分析表明，来自这两个系统的所有基因在培养基对数生长期均有表达。CRISPR 2.1和2.2的直接重复序列相同，且存在于其他spp.的阵列中，包括和，但CRISPR1不存在。我们搜索了潜在的间隔序列靶标，发现这两个系统之间存在有趣的差异：CRISPR1（I-E型）的靶标只有9%在噬菌体序列中，91%在质粒序列中。相反，约66%的CRISPR2（I-F型）靶标存在于噬菌体基因组中。我们的结果突出了蚊子肠道相关细菌中CRISPR位点的存在，并表明在进化过程中共生体与入侵的移动遗传元件之间存在相互作用。
