Sequenced T (translucent or distinct) variants with a <i>motA</i> mutation listed by type (see Figure 3).

1<p>Percentage of variants out of 18 total.</p>2<p>Reversion of the mutation confirmed by sequence analysis. N/D indicates that analysis was not done for this single variant.</p

Nucleotide alignment of <i>motA</i> and mutated alleles.

<p>The four mutations found within <i>motA</i> 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).</p

Amino acid alignment of MotA.

<p>The <i>motA</i> 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 <i>motA</i> 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).</p

High Frequency, Spontaneous <i>motA</i> Mutations in <i>Campylobacter jejuni</i> Strain 81-176

<div><p><i>Campylobacter jejuni</i> is an important cause of bacterial diarrhea worldwide. The pathogenesis of <i>C. jejuni</i> is poorly understood and complicated by phase variation of multiple surface structures including lipooligosaccharide, capsule, and flagellum. When <i>C. jejuni</i> strain 81-176 was plated on blood agar for single colonies, the presence of translucent, non-motile colonial variants was noted among the majority of opaque, motile colonies. High-throughput genomic sequencing of two flagellated translucent and two opaque variants as well as the parent strain revealed multiple genetic changes compared to the published genome. However, the only mutated open reading frame common between the two translucent variants and absent from the opaque variants and the parent was <i>motA</i>, encoding a flagellar motor protein. A total of 18 spontaneous <i>motA</i> mutations were found that mapped to four distinct sites in the gene, with only one class of mutation present in a phase variable region. This study exemplifies the mutative/adaptive properties of <i>C. jejuni</i> and demonstrates additional variability in <i>C. jejuni</i> beyond phase variation.</p></div

Derivation of 81-176/55 and the appearance of colonial variants linked with motility.

<p>(A) Cartoon depicting the origin of the sequenced strains. Abbreviations include O for opaque and T for translucent. (B) Appearance of colonial variants of <i>C. jejuni</i> 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 <i>C. jejuni</i> strain 81-176.</p

Schematic illustration of the 69-176/55 and its 4 additional sequenced offspring.

<p>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 <i>hup</i> and <i>cysK</i>. An incomplete direct repeat (IDR) bracketing the deletion is indicated.</p