Figure 1.
Derivation of 81-176/55 and the appearance of colonial variants linked with motility.
(A) Cartoon depicting the origin of the sequenced strains. Abbreviations include O for opaque and T for translucent. (B) Appearance of colonial variants of C. jejuni 81-176 grown on CBA plates in microaerobic conditions following dilution and plating. Colony morphology was examined on CBA (C) as well as MH agar (D) and motility analysis made use of 0.6% BB agar 24-well plates with single colonies stabbed into the wells. (E) Transmission electron microscopy images of negatively stained WT, opaque, and translucent variants of C. jejuni strain 81-176.
Figure 2.
Schematic illustration of the 69-176/55 and its 4 additional sequenced offspring.
The assembly of the whole genome sequences revealed varying SNPs throughout the chromosome. One confirmed difference between the previously sequenced 81-176 and 81-176/55 (as well as the opaque and translucent progeny) was the presence of a 69 bp deletion in the intergenic region between hup and cysK. An incomplete direct repeat (IDR) bracketing the deletion is indicated.
Figure 3.
Nucleotide alignment of motA and mutated alleles.
The four mutations found within motA have been assigned a type for ease in distinguishing. Type A mutation is a deletion at base 64 (T158). Type B mutation is a missense mutation at base 262 (T1). Type C mutation is a duplication of 49 bp (boxed) creating a direct repeat (T108). Type D mutation is a nonsense mutation at base 612 (T3).
Figure 4.
The motA mutations are predicted to result in non-functional proteins. A missense mutation at base 262 (T1, Type B) resulted in an A to P mutation at amino acid 88; a nonsense mutation at base 612 (T3, Type D) resulted in a premature truncation; a duplication of 49 bp created a direct repeat within motA and led to the replacement of the last 73 residues in the C-terminus with a sequence of 39 new residues that are highlighted (T108, Type C); and a deletion at base 64 resulting in a truncated protein (T158, Type A).
Table 1.
Sequenced T (translucent or distinct) variants with a motA mutation listed by type (see Figure 3).