Identification of the Csr global regulatory system mediated by small RNA decay in Aeromonas salmonicida

• Published in: Journal of general and applied microbiology Vol. 70; no. 1; p. 2023.12.004
• Main Authors: Suzuki, Kazushi, Yoshida, Masaki, Gladyshchuk, Olga, Sugimoto, Hayuki, Togashi, Koume
• Format: Journal Article
• Language: English
• Published: Japan Applied Microbiology, Molecular and Cellular Biosciences Research Foundation 01.01.2024; Japan Science and Technology Agency
• Subjects: Aeromonas salmonicida; Aeromonas salmonicida - genetics; Aeromonas salmonicida - metabolism; Amino Acid Sequence; Amino acids; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biofilms; Biofilms - growth & development; Biosynthesis; Carbon sequestration; Chitinase; Conserved sequence; Csr system; csrD; Decay; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Flagella; Functional analysis; Gene Expression Regulation, Bacterial; Genes; Glycogen; Glycogen - metabolism; Glycogens; Motility; Nucleotide sequence; Phenotypes; Proteins; Repressor Proteins; Ribonucleic acid; RNA; RNA decay; RNA Stability; RNA, Bacterial - genetics; RNA-binding protein; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; RNA decay; Aeromonas salmonicida; motility; csrD; Csr system
• ISSN: 0022-1260; 1349-8037
• DOI: 10.2323/jgam.2023.12.004

We investigated the presence and functionality of the carbon storage regulator (Csr) system in Aeromonas salmonicida SWSY-1.411. CsrA, an RNA-binding protein, shared 89% amino acid sequence identity with Escherichia coli CsrA. CsrB/C sRNAs exhibited a typical stem-loop structure, with more GGA motifs, which bind CsrA, than E. coli. CsrD had limited sequence identity with E. coli CsrD; however, it contained the conserved GGDEF and EAL domains. Functional analysis in E. coli demonstrated that the Csr system of A. salmonicida influences glycogen biosynthesis, biofilm formation, motility, and stability of both CsrB and CsrC sRNAs. These findings suggest that in A. salmonicida, the Csr system affects phenotypes like its E. coli counterpart. In A. salmonicida, defects in csr homologs affected biofilm formation, motility, and chitinase production. However, glycogen accumulation and protease production were unaffected. The expression of flagellar-related genes and chitinase genes was suppressed in the csrA-deficient A. salmonicida. Northern blot analysis indicated the stabilization of CsrB and CsrC in the csrD-deficient A. salmonicida. Similar to that in E. coli, the Csr system in A. salmonicida comprises the RNA-binding protein CsrA, the sRNAs CsrB and CsrC, and the sRNA decay factor CsrD. This study underscores the conservation and functionality of the Csr system and raises questions about its regulatory targets and mechanisms in A. salmonicida.