genome evolution and the emergence of fruiting body development in myxococcus xanthus基因组进化和子实体的出现发展myxococcus克桑托斯.pdfVIP

Genome Evolution and the Emergence of Fruiting Body Development in Myxococcus xanthus 1 2 2 Barry Goldman , Swapna Bhat , Lawrence J. Shimkets * 1 Applied Bioinformatics, Monsanto Company, St. Louis, Missouri, United States of America, 2 Department of Microbiology, University of Georgia, Athens, Georgia, United States of America Background. Lateral gene transfer (LGT) is thought to promote speciation in bacteria, though well-defined examples have not been put forward. Methodology/Principle Findings. We examined the evolutionary history of the genes essential for a trait that defines a phylogenetic order, namely fruiting body development of the Myxococcales. Seventy-eight genes that are essential for Myxococcus xanthus development were examined for LGT. About 73% of the genes exhibit a phylogeny similar to that of the 16S rDNA gene and a codon bias consistent with other M. xanthus genes suggesting vertical transmission. About 22% have an altered codon bias and/or phylogeny suggestive of LGT. The remaining 5% are unique. Genes encoding signal production and sensory transduction were more likely to be transmitted vertically with clear examples of duplication and divergence into multigene families. Genes encoding metabolic enzymes were frequently acquired by LGT. Myxobacteria exhibit aerobic respiration unlike most of the d Proteobacteria. M. xanthus contains a unique electron transport pathway shaped by LGT of genes for succinate dehydrogenase and three cytochrome oxidase complexes. Conclusions/Significance. Fruiting body development depends on genes acquired by LGT, particularly those involved in polysaccharide production. We suggest that aerobic growth fostered innovation necessary for development by allowing myxobacteria access to a different gene pool from anaerobic members of the d Proteobacteria. Habitat destruction and loss