ntegrative and conjugative elements from the SXT/R391 family contribute to the dissemination of antiphage systems.

DANIELA PIRAJAN; SUSANA VAZQUEZ; CECILIA QUIROGA

Quilmes

Congreso; ISME-Lat 2023; 2023

ISME

Integrative and conjugative elements (ICEs) from the SXT/R391 family participate in thetransfer of genetic material between bacteria contributing to the dissemination of genetictraits to different habitats. Their structure consists of several conserved core regionsinterrupted by genes encoding metal or antimicrobial resistance genes (ARG), mobilegenetic elements, defense systems [DS: toxin/antitoxin (TA), restriction/modification (RM),bacteriophage exclusion (BREX), abortive infection (Abi) etc.)], as well as other beneficialgenes. Recently, new anti-phage (Doron) systems were described in bacterial genomes. Theaim of this work was to identify all antiviral systems encoded within ICEs from the SXT/R391family. Therefore, we searched for these elements in 68120 complete genomes available inGenbank as of March 7th, 2022. We detected 147 SXT/R391 ICEs distributed amongEnterobacterales (66), Vibrionales (52), Alteromonadales (26), Pasteurellales (1),Thiotrichales (1), and Oceanospirillales (1). Bacteria harboring these ICEs were widelyspread in different habitats, -clinical (39), aquatic (34), animal-host (51), human-impactedniches (10), and roots (1). The study of the SXT/R391 platform found innon-Enterobacterales genomes (81) showed that 77 were inserted at gene prfC,corresponding to the canonical type 1 structure. Their genetic content was analyzed usingISFinder v2.0, CARD v4.0, PADLOC v1.1.0, DefenseFinder v1.0.2 and TADB 2.0 softwares,which revealed the presence of insertion sequences (81/81), ARGs (31/81), and numerousDS (77/81). In addition to the known DS (RM, 41; BREX, 24; AbiE, 38; TA, 44), our studyrevealed also the presence of several Doron systems (CBASS, 14; Gabija A/b,15; GaoLetS/A,16; Gao R, 3; MOKOSH, 6; PrrC, 8; Kiwa, 7; Rosmer, 6; Lamassu, 1 and Rst 3HP, 6).Most ICEs carried between 3 and 5 DS from different families. Our work confirms thatSXT/R391 ICEs found in diverse species can harbor a wide variety of genes (ARG, DS)contributing to their survival in different niches. Furthermore, the co-occurrence of severaldefense systems in a single SXT/R391 ICE suggests that these platforms are major playersin the dissemination of antiphage mechanisms involved in host protection.