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In the phylogenetic footsteps of ATP- ADP translocases
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Molecular Evolution.
Manuscript (Other academic)
URN: urn:nbn:se:uu:diva-89690OAI: oai:DiVA.org:uu-89690DiVA: diva2:161376
Available from: 2002-03-06 Created: 2002-03-06 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Patterns and Processes of Molecular Evolution in Rickettsia
Open this publication in new window or tab >>Patterns and Processes of Molecular Evolution in Rickettsia
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Species of the genus Rickettsia are obligate intracellular parasites of the a-proteobacterial subdivision. It has been suggested that obligate intracellular bacteria have evolved from free-living bacteria with much larger genome sizes. Transitions to intracellular growth habitats are normally associated with radical genomic alterations, particularly genome rearrangements and gene losses.

This thesis presents a comparative study of evolutionary processes such as gene rearrangements, deletions and duplications in a variety of Rickettsia species. The results show that early intrachromosomal recombination events mediated by duplicated genes and short repeats have resulted in deletions as well as rearrangements. For example, an exceptional organization of the elongation factor genes was found in all species examined, suggesting that this rearrangement event occurred at the early stage of the evolution of Rickettsia. Likewise, it was found that a repetitive element, the so-called Rickettsia Palindromic Element (RPE) flourished prior to species divergence in Rickettsia. Finally, a phylogenetic analysis shows that the duplication events that gave rise to the five genes encoding ATP/ADP transporters occurred long before the divergence of the two major groups of Rickettsia. Taken together, this suggests that Rickettsia have been intracellular parasites for an extensive period of time.

A detailed analysis of the patterns of nucleotide changes in genes and intergenic regions among the different species provides evidence for a gradual accumulation of short deletions. This suggests that different distributions of genes and repeated sequences in modern Rickettsia species reflect species-specific differences in rates of deterioration rather than variation in rates of intra-genomic sequence proliferation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2002. 40 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 689
Developmental biology, Utvecklingsbiologi
National Category
Developmental Biology
Research subject
Molecular Biology
urn:nbn:se:uu:diva-1789 (URN)91-554-5248-5 (ISBN)
Public defence
2002-03-22, Lindahlsalen, Uppsala, 10:00
Available from: 2002-03-06 Created: 2002-03-06Bibliographically approved

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