TY - JOUR
T1 - Evidence for diversifying selection at the pyoverdine locus of Pseudomonas aeruginosa
AU - Smith, Eric E.
AU - Sims, Elizabeth H.
AU - Spencer, David H.
AU - Kaul, Rajinder
AU - Olson, Maynard V.
PY - 2005/3
Y1 - 2005/3
N2 - Pyoverdine is the primary siderophore of the gram-negative bacterium Pseudomonas aeruginosa. The pyoverdine region was recently identified as the most divergent locus alignable between strains in the P. aeruginosa genome. Here we report the nucleotide sequence and analysis of more than 50 kb in the pyoverdine region from nine strains of P. aeruginosa. There are three divergent sequence types in the pyoverdine region, which correspond to the three structural types of pyoverdine. The pyoverdine outer membrane receptor fpvA may be driving diversity at the locus: it is the most divergent alignable gene in the region, is the only gene that showed substantial intratype variation that did not appear to be generated by recombination, and shows evidence of positive selection. The hypothetical membrane protein PA2403 also shows evidence of positive selection; residues on one side of the membrane after protein folding are under positive selection. R′, previously identified as a type IV strain, is clearly derived from a type III strain via a 3.4-kb deletion which removes one amino acid from the pyoverdine side chain peptide. This deletion represents a natural modification of the product of a nonribosomal peptide synthetase enzyme, whose consequences are predictive from the DNA sequence. There is also linkage disequilibrium between the pyoverdine region and pvdY, a pyoverdine gene separated by 30 kb from the pyoverdine region. The pyoverdine region shows evidence of horizontal transfer; we propose that some alleles in the region were introduced from other soil bacteria and have been subsequently maintained by diversifying selection.
AB - Pyoverdine is the primary siderophore of the gram-negative bacterium Pseudomonas aeruginosa. The pyoverdine region was recently identified as the most divergent locus alignable between strains in the P. aeruginosa genome. Here we report the nucleotide sequence and analysis of more than 50 kb in the pyoverdine region from nine strains of P. aeruginosa. There are three divergent sequence types in the pyoverdine region, which correspond to the three structural types of pyoverdine. The pyoverdine outer membrane receptor fpvA may be driving diversity at the locus: it is the most divergent alignable gene in the region, is the only gene that showed substantial intratype variation that did not appear to be generated by recombination, and shows evidence of positive selection. The hypothetical membrane protein PA2403 also shows evidence of positive selection; residues on one side of the membrane after protein folding are under positive selection. R′, previously identified as a type IV strain, is clearly derived from a type III strain via a 3.4-kb deletion which removes one amino acid from the pyoverdine side chain peptide. This deletion represents a natural modification of the product of a nonribosomal peptide synthetase enzyme, whose consequences are predictive from the DNA sequence. There is also linkage disequilibrium between the pyoverdine region and pvdY, a pyoverdine gene separated by 30 kb from the pyoverdine region. The pyoverdine region shows evidence of horizontal transfer; we propose that some alleles in the region were introduced from other soil bacteria and have been subsequently maintained by diversifying selection.
UR - http://www.scopus.com/inward/record.url?scp=14644394879&partnerID=8YFLogxK
U2 - 10.1128/JB.187.6.2138-2147.2005
DO - 10.1128/JB.187.6.2138-2147.2005
M3 - Article
C2 - 15743962
AN - SCOPUS:14644394879
SN - 0021-9193
VL - 187
SP - 2138
EP - 2147
JO - Journal of bacteriology
JF - Journal of bacteriology
IS - 6
ER -