Mechanisms of evolution in Rickettsia conorii and R. prowazekii

Science. 2001 Sep 14;293(5537):2093-8. doi: 10.1126/science.1061471.


Rickettsia conorii is an obligate intracellular bacterium that causes Mediterranean spotted fever in humans. We determined the 1,268,755-nucleotide complete genome sequence of R. conorii, containing 1374 open reading frames. This genome exhibits 804 of the 834 genes of the previously determined R. prowazekii genome plus 552 supplementary open reading frames and a 10-fold increase in the number of repetitive elements. Despite these differences, the two genomes exhibit a nearly perfect colinearity that allowed the clear identification of different stages of gene alterations with gene remnants and 37 genes split in 105 fragments, of which 59 are transcribed. A 38-kilobase sequence inversion was dated shortly after the divergence of the genus.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological
  • Chlamydia / genetics
  • Computational Biology
  • DNA, Bacterial / genetics
  • DNA, Intergenic
  • Evolution, Molecular*
  • Gene Dosage
  • Gene Silencing
  • Gene Transfer, Horizontal
  • Genes, Bacterial
  • Genome, Bacterial*
  • Open Reading Frames
  • Phylogeny
  • Polymerase Chain Reaction
  • Repetitive Sequences, Nucleic Acid
  • Rickettsia / genetics
  • Rickettsia conorii / genetics*
  • Rickettsia conorii / physiology
  • Rickettsia prowazekii / genetics*
  • Rickettsia prowazekii / physiology
  • Sequence Analysis, DNA
  • Transcription, Genetic


  • DNA, Bacterial
  • DNA, Intergenic