Pseudogenes, junk DNA, and the dynamics of Rickettsia genomes
2001 (English)In: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 18, no 5, 829-839 p.Article in journal (Refereed) Published
Studies of neutrally evolving sequences suggest that differences in eukaryotic genome sizes result from different rates of DNA loss. However, very few pseudogenes have been identified in microbial species, and the processes whereby genes and genomes deteriorate in bacteria remain largely unresolved. The typhus-causing agent, Rickettsia prowazekii, is exceptional in that as much as 24% of its 1.1-Mb genome consists of noncoding DNA and pseudogenes. To test the hypothesis that the noncoding DNA in the R. prowazekii genome represents degraded remnants of ancestral genes, we systematically examined all of the identified pseudogenes and their flanking sequences in three additional Rickettsia species. Consistent with the hypothesis, we observe sequence similarities between genes and pseudogenes in one species and intergenic DNA in another species. We show that the frequencies and average sizes of deletions are larger than insertions in neutrally evolving pseudogene sequences. Our results suggest that inactivated genetic material in the Rickettsia genomes deteriorates spontaneously due to a mutation bias for deletions and that the noncoding sequences represent DNA in the final stages of this degenerative process.
Place, publisher, year, edition, pages
2001. Vol. 18, no 5, 829-839 p.
genome degradation, molecular evolution, noncoding DNA, pseudogenes, Rickettsia
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:uu:diva-38212ISI: 000168427400014OAI: oai:DiVA.org:uu-38212DiVA: diva2:66111
Addresses: Andersson SGE, Uppsala Univ, Evolutionary Biol Ctr, Dept Mol Evolut, Norbyvagen 18C, S-75236 Uppsala, Sweden. Uppsala Univ, Evolutionary Biol Ctr, Dept Mol Evolut, S-75236 Uppsala, Sweden.2008-10-172008-10-172014-05-14Bibliographically approved