Fig. 1

Structural comparison between SXT and six ICEs from V. alginolyticus. a Schematic representation of the 52 core genes of SXT/R391 ICEs. Left lower part is the normal int/xis module of SXT/R391 ICEs, and the upper left part shows the alternative int/xis modules of ICEValA056-2, ICEValHN396 and ICEValHN437. Atypical insertions of ORFs of these ICEs and an extra copy of exo gene (pale green) of ICEValA056-2 are indicated with fold-down arrows. The absences of s025 and s026 in ICEValE0601/ICEValHN492 are shown with red crosses. b Variable ICE regions are shown with colors according to the elements in which they were originally described: SXT (blue), ICEValA056-1 (dark red), ICEValA056-2 (pale green), ICEValE0601/ICEValHN492 (red), ICEValHN396 (dark green) and ICEValHN437 (pink). Thin arrows indicate the sites of insertion for each VR region (I, II and III) and HS1–HS5 represent hotspots 1–5. Some notable genes in these regions are marked. Tm, trimethoprim cassette; Cm, chloramphenicol cassette; Sm, streptomycin cassette; Su, sulfamethoxazole cassette; mosAT, toxin-antitoxin system; prrABCD, an novel operon including a RM system and anticodon nuclease gene. Variable region III is shown at the top of the backbone of SXT/R391 ICEs for saving space