Phylogenetic relationships of Campylobacter jejuni based on porA sequences.
Campylobacter porins are the dominant major outer membrane protein (MOMP) of these bacteria. They are composed of hypervariable, surface-exposed, peptide loops and membrane-embedded, conserved peptide regions. Porins are functionally important and may also be useful for molecular subtyping methods but have not yet been well characterized. We therefore sequenced the porA gene from 39 Campylobacter isolates, including multilocus sequence type (MLST) reference strains, isolates from patients with the Guillain-Barré syndrome, other clinical isolates, and serotyping reference strains. These were compared with additional sequences available from GenBank. Three distinct porA lineages were observed after phylogenetic analysis. Both Campylobacter coli and Campylobacter jejuni were found with group 3 porA sequences, and this was the only group showing any evidence of recombination among porA genes. There was no recombination between porA genes from C. jejuni groups 1 and 2, suggesting there may be functional constraints on changes at this locus. Most of the amino acid differences among the three groups were present in surface-exposed loops, and dissimilar substitutions were found when groups 1 and 2 MOMP were compared. Different MOMP sequence groups may have different biological or antigenic properties, which in turn may be associated with survival in different environments, host adaptation, or virulence.
Clark
Clifford G
CG
National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB. Clifford_Clark@phac-aspc.gc.ca
Beeston
Anne
A
Bryden
Louis
L
Wang
Gehua
G
Barton
Connie
C
Cuff
Wilfred
W
Gilmour
Matthew W
MW
Ng
Lai-King
LK
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification* / Q000235:genetics*; D017000:Campylobacter coli / Q000145:classification / Q000235:genetics; D016123:Campylobacter jejuni / Q000145:classification / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D018272:Porins / Q000145:classification* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D018272:Porins; C095080:major outer membrane protein, Campylobacter jejuni