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Genome reduction in the alpha-Proteobacteria
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
2005 (English)In: Current Opinion in Microbiology, ISSN 1369-5274, E-ISSN 1879-0364, Vol. 8, no 5, 579-585 p.Article in journal (Refereed) Published
Abstract [en]

More than 20 α-proteobacterial genomes are currently available. These range in size from 1–9 Mb and represent excellent model systems for evolutionary studies of the organizational features of bacterial genomes. Computational inferences have shown that genome reductions have occurred independently in lineages such as Rickettsia and Bartonella that are associated with intracellular lifestyles. Analyses of these reduced genomes have provided insights into the evolution of vector-borne transmission pathways. Further research into the population biology of bacteria, arthropods and vertebrate hosts will help to refine the biology of host–pathogen interactions and will facilitate the design of vaccines and vector-control programs.

Place, publisher, year, edition, pages
2005. Vol. 8, no 5, 579-585 p.
Keyword [en]
Adaptation; Biological/genetics, Alphaproteobacteria/*genetics, Animals, Eukaryotic Cells/microbiology, Evolution; Molecular, Genome; Bacterial, Humans, Phylogeny, Recombination; Genetic, Research Support; Non-U.S. Gov't, Sequence Deletion
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-77159DOI: 10.1016/j.mib.2005.08.002PubMedID: 16099701OAI: oai:DiVA.org:uu-77159DiVA: diva2:105071
Available from: 2006-03-13 Created: 2006-03-13 Last updated: 2011-02-18Bibliographically approved
In thesis
1. Evolutionary Processes and Genome Dynamics in Host-Adapted Bacteria
Open this publication in new window or tab >>Evolutionary Processes and Genome Dynamics in Host-Adapted Bacteria
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many bacteria live in close association with other organisms such as plants and animals, with important implications for both health and disease. This thesis investigates bacteria that are well adapted to live inside an animal host, and describes the molecular evolutionary processes underlying host-adaptation, based on bacterial genome comparisons.

Insect-transmitted bacteria of the genus Bartonella infect the red blood cells of mammals, and we investigate host adaptation and genome evolution in this genus. In Bartonella, many host-interaction systems are encoded in a highly variable chromosomal segment previously shown to be amplified and packaged into bacteriophage particles. Among all genes imported into the Bartonella ancestor, we identify the short gene cluster encoding these phage particles as the most evolutionary conserved, indicating a strong selective advantage and a role in niche adaptation. We also provide an overview of the remarkable evolutionary dynamics of type IV and type V secretion systems, including a detailed analysis of the type IV secretion system trw. Our results highlight the importance of recombination and gene conversion in the evolution of host-adaptation systems, and reveal how these mutational mechanisms result in strikingly different outcomes depending on the selective constraints.

In the insect endosymbionts Buchnera and Blochmannia, we show that genes frameshifted at poly(A) tracts can remain functional due to transcriptional slippage. Selection against poly(A) tracts is very inefficient in these genomes compared to other bacteria, and we discuss why this can lead to increased rates of gene loss. Using the human pathogen Helicobacter pylori as a model, we provide a deeper understanding of why highly expressed genes evolve slowly.

This thesis emphasizes the power of using complete genome sequences to study evolutionary processes. In particular, we argue that knowledge about the complex evolution of duplicated gene segments is crucial to understand host adaptation in bacteria.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 64 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 668
molecular evolution, pathogen, secretion system, Bartonella, Buchnera, Blochmannia, Helicobacter
National Category
Bioinformatics and Systems Biology
Research subject
Evolutionary Genetics
urn:nbn:se:uu:diva-107720 (URN)978-91-554-7596-3 (ISBN)
Public defence
2009-10-09, Lindahlsalen, EBC, Norbyvägen 18, Uppsala, 09:15 (English)
Available from: 2009-09-18 Created: 2009-08-24 Last updated: 2009-09-22

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