Oct 4, 2012

An evolutionary link between natural transformation and CRISPR adaptive immunity

MBio
Peter Jorth, Marvin Whiteley

Abstract

Natural transformation by competent bacteria is a primary means of horizontal gene transfer; however, evidence that competence drives bacterial diversity and evolution has remained elusive. To test this theory, we used a retrospective comparative genomic approach to analyze the evolutionary history of Aggregatibacter actinomycetemcomitans, a bacterial species with both competent and noncompetent sister strains. Through comparative genomic analyses, we reveal that competence is evolutionarily linked to genomic diversity and speciation. Competence loss occurs frequently during evolution and is followed by the loss of clustered regularly interspaced short palindromic repeats (CRISPRs), bacterial adaptive immune systems that protect against parasitic DNA. Relative to noncompetent strains, competent bacteria have larger genomes containing multiple rearrangements. In contrast, noncompetent bacterial genomes are extremely stable but paradoxically susceptible to infective DNA elements, which contribute to noncompetent strain genetic diversity. Moreover, incomplete noncompetent strain CRISPR immune systems are enriched for self-targeting elements, which suggests that the CRISPRs have been co-opted for bacterial gene regulation, similar ...Continue Reading

  • References48
  • Citations30
  • References48
  • Citations30

Citations

Mentioned in this Paper

Immune System
Transformation, Genetic
Genome
Pathogenic Organism
Recombination, Genetic
Aggregatibacter actinomycetemcomitans
RNA Interference Pathway
Gene Transfer, Horizontal
Genomics
Host Specificity

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