Search tips
Search criteria 


Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
J Bacteriol. 1991 June; 173(12): 3894–3900.
PMCID: PMC208022

Nucleotide sequences of the gnd genes from nine natural isolates of Escherichia coli: evidence of intragenic recombination as a contributing factor in the evolution of the polymorphic gnd locus.


Nine natural isolates of Escherichia coli were examined, and the sequence of the entire 1,404 bases of the gnd gene (6-phosphogluconate dehydrogenase, EC was determined. These isolates, along with E. coli K-12, constitute 10 strains for analysis. (The sequence of the E. coli K-12 gnd gene is known.) A total of 184 sites were polymorphic, and up to 6% sequence divergence was observed between pairs of strains. The deduced amino acid sequences showed much more variation than had been shown by multilocus enzyme electrophoresis, and in addition the net charge calculated did not correlate strongly with electrophoretic mobility. A phylogenetic tree for the sequences that was based on maximum parsimony differed significantly from a tree for the same strains that was based on multilocus enzyme electrophoresis for 35 enzymes (R. K. Selander, D. A. Caugant, and T. S. Whittam, p. 1625-1648, in F. C. Neidhardt, J. L. Ingraham, K. B. Low, B. Magasanik, M. Schaechter, and H. E. Umbarger, ed., Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology, 1987). These data, together with analysis of sequence variation between the strains, indicated that intragenic recombination and transfer of the whole of gnd have occurred in the evolution of these strains. There is evidence of one recombination event between E. coli and Salmonella typhimurium.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.2M), or click on a page image below to browse page by page.

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)