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Title: Analysis of co-evolving genes in campylobacter jejuni and C. coli

Author
item SNIPEN, L - Norwegian University Of Life Sciences
item Meinersmann, Richard - Rick
item LAGESEN, K - University Of Oslo
item KATHARIOU, S - North Carolina State University
item ALTERMAN, E - Grassland Research Institute
item OLSON, J - North Carolina State University
item KNOCHEL, S - Copenhagen University
item WASSENAAR, T - Molecular Microbiology And Genomics Consultants

Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/5/2011
Publication Date: 5/21/2012
Citation: Snipen, L., Meinersmann, R.J., Lagesen, K., Kathariou, S., Alterman, E., Olson, J., Knochel, S., Wassenaar, T. 2012. Analysis of co-evolving genes in campylobacter jejuni and C. coli. American Society for Microbiology Annual Meeting. June 16-19, 2012. San Francisco, California.

Interpretive Summary:

Technical Abstract: Background: The population structure of Campylobacter has been frequently studied by MLST, for which fragments of housekeeping genes are compared. We wished to determine if the used MLST genes are representative of the complete genome. Methods: A set of 1029 core gene families (CGF) was identified at least once in 25 sequenced genomes of C. jejuni, C. coli and C. lari. We employed different approaches to reveal the evolutionary histories of these CGFs and represented each as a vector in a ‘phylogenetic space'. Results: A consensus cladogram of maximum likelihood trees for individual CGFs did not have sufficient discrimination to separate the majority of C. jejuni genomes. Topological distances of the phylogenetic trees gave different evolutionary histories for all 1029 trees, though the results were more ordered than random trees. Partitioning of genomes by evolutionary distances placed the CGFs into 106 different groups, of which 90 were singletons. The largest group (788 GCFs) showed congruity within the three species. Six MLST genes were in this group, but aspA was not. Principal component analysis (PCA) of normalized pairwise evolutionary distances resulted in the first three components explaining more than 80% of the variation. Considering all CGFs in this three-dimensional space, most were found in a dense region where 5 of the MLST genes were also located (aspA was not). Recombination distance and COG functional descriptions of these CGFs were computed and used to test whether regions of the vector spaces were enriched with genes with a particular feature. One distinct region in the PCA evolutionary space contained CGFs highly enriched with genes under positive selection; another region was rich in genes with high recombination rate. Conclusion: The PCA of the normalized pairwise evolutionary distances resulted in representation of the CGFs that appears to correlate with factors affecting evolution.