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Horizontal gene transfer in prokaryotes: quantification and classification
E V Koonin1, K S Makarova, L Aravind
1National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA. koonin@ncbi.nlm.nih.gov
Annual Review of Microbiology
|September 7, 2001
Summary
Prokaryotic genomes frequently acquire genes through horizontal gene transfer, influenced by lifestyle. These gene acquisitions often provide selective advantages, such as antibiotic resistance in bacteria.
Area of Science:
- Genomics
- Evolutionary Biology
- Microbiology
Background:
- Prokaryotic genomes show significant gene content derived from horizontal gene transfer (HGT).
- HGT patterns correlate with organismal lifestyle and environmental niche.
- HGT can involve acquiring new genes, paralogs, or displacing existing genes with orthologs (xenologs).
Purpose of the Study:
- To analyze the extent and implications of horizontal gene transfer in prokaryotic genomes.
- To investigate the relationship between HGT, organism lifestyle, and selective advantages.
- To explore specific examples of HGT events and their evolutionary significance.
Main Methods:
- Comparative genomic analysis of bacterial, archaeal, and eukaryotic genomes.
- Classification of horizontal gene transfer events.
- Case studies examining specific gene acquisitions and their functional roles.
Main Results:
- A substantial portion of prokaryotic genes originate from HGT.
- Gene transfer patterns vary, with hyperthermophiles showing extensive archaeal exchange and parasitic bacteria acquiring eukaryotic genes.
- Acquired genes, such as isoleucyl-tRNA synthetases and proteases, confer selective advantages like antibiotic resistance and potential roles in pathogenesis.
Conclusions:
- Horizontal gene transfer is a major driver of prokaryotic genome evolution.
- The selective benefits of HGT are evident in cases linked to antibiotic resistance and pathogenicity.
- Understanding HGT mechanisms and outcomes is crucial for evolutionary and applied microbiology.