FIGURE 2.

Identification of tRNA-leu^UUG as the putative attB insertion site of ICEMh1-like elements and predicted host range. (A) Schematic for ICE orientation and random PCR mapping of ICEMh1^PM22 junctions in 18 Mannheimia haemolytica and 18 Pasteurella multocida transconjugants. ICEMh1^PM22 insertions in every transconjugant were identical and aligned to a specific tRNA-leu in the genomes of P. multocida strain 36950 and M. haemolytica M42548. (B) Sequence logo of left and right MUSCLE-aligned junctions identified in 41 Pasteurellaceae harboring ICEMh1-like sequences. The left and right ends of ICEMh1-like variants contain a conserved direct repeat (DR; 5′-GATTCAAAATC-3′) attL conserves the tRNA TψC loop’s imperfect palindrome (5′-CGGTTCGAGTCCG-3′). The attL and attR sites are designated with respect to ICEPmu1 in Michael et al. (2011b). (C) Neighbor-joining tree of all tRNA-leu from 41 Pasteurellaceae harboring ICEMh1-like sequences. All ICEMh1-like insertions were associated with tRNA-leu^UUG. (D) Predicted structure of tRNA-leu^UUG showing presumptive ICEMh1 attB attachment site (also encoding the tRNA anticodon) and palindrome. (E) Frequencies of tRNA-leu codon types in 41 Pasteurellaceae harboring ICEMh1-like sequences. (F) Predicted host range of ICEMh1-like elements based on tRNA-leu^UUG alignment by BLAST and strict (100% identity) conservation of direct repeat and palindrome. Colors are arbitrary.