Scholarly record

CRISPR/CAS IN GENOMES OF SINORHIZOBIUM MELILOTI

Maria E. Vladimirova, Viktoria Muntyan, А.Д. Козлова, Grudinin Mp, Marina L. Roumiantseva

Abstract

Currently, CRISPR/Cas systems are actively studied bacterial systems, due to the possibilitpossibility to apply them for targeted editing of eukaryotic genomes. CRISPR/Cas systems are belonged to adaptive immun immune system of bacteria and archaea acting against invading mobile genetic elements (MGEs: bacteriophages and integrative conjugative elements ). Curre Currently CRISPR/Cas systems were detected in genomes of 75% of known archaea and 36 % of bacteria strains . However, there are still quite less knowledge about CRISPR/Cas systems in genomes of nitrogen nitrogen-fixing nodule bacteria. Sinorhizobium meliloti are agricultu agriculturally valuable species of soil bacteria that form nitrogennitrogen-fixing symbiosis with alfalfa cross cross-inoculation group. Evaluation of adaptive immunimmune systems protecting root nodule bacteria against external foreign DNA is actual; since S. meliloti is actively in involved in horizontal gene transfer occurred in rhizosphere and soil microbiome where lysogenic phages and conjugative mobile elements are abund ant . The aim of this work was to search and study diversity of CRISPR/Cas in S. melilotimeliloti. CRISPR/Cas sequences we re identified by b ioinformatics analysis of full -genome sequenced of 22 S. meliloti strains posted in GenBank. The prediction of potential CRISPR/Cas sequences was done by using CRISPRCas++ CRISPRCas++, genomic islands (GIs) and prophages (Phs) were identified by appl applying Islander algorithm and PHASTER, respectively. For the first time we are reporting here about potential CRISPR sequences (hereinafter CRISPR sequences ) in S. meliloti genomes. The number of sequences of interest varied from 3 to 9 among tested strain strains. Besides that sequences encoding Cas3 a potential element of CRISPR/Cas system of Type I were identified on chromosome and megaplasmid SMb. Some sequences a mong identified CRISPR were unique unique, while others were common for all tested genetically distant stra strains. CRISPR spacer sequences identified in S. meliloti are most mostly similar to fragments of phages from Siphoviridae and Podoviridae familiesfamilies. Summarizing, CRISPR sequences in S. meliloti are located not only on chromosome, but on megaplasmids and on cryptic plasmids as well. These elements of adaptive immunity systems of S. meliloti aimed to protect bacteria cells from bacteriophages mainly from Siphoviridae and Podoviridae families widely ab abou nd ed in soil microbiomes. This work is supported by the RSF 20 20-16 -00105.

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