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Interactions of photosynthesis with genome size and function
John A Raven1, John Beardall, Anthony W D Larkum
1School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia. j.a.raven@dundee.ac.uk
Summary
Photolithotrophs, organisms using light for energy, exhibit slower growth rates and larger genomes than chemoorganotrophs due to energy allocation to photosynthesis. They also face unique challenges like reactive oxygen species and UV radiation.
Area of Science:
- Microbiology
- Biochemistry
- Evolutionary Biology
Background:
- Photolithotrophs utilize light energy, differing in their electron donors (water vs. other compounds).
- Oxygenic photosynthesis, common in Cyanobacteria and eukaryotes, evolved later than anoxygenic photosynthesis found in bacteria.
- The evolution of oxygenic photosynthesis significantly altered Earth's atmosphere and biogeochemical cycles.
Purpose of the Study:
- To compare the genomic and growth characteristics of photolithotrophs and chemoorganotrophs.
- To investigate the inherent challenges and evolutionary adaptations associated with photosynthesis.
- To explore the impact of atmospheric changes, particularly oxygenation, on microbial life.
Main Methods:
- Comparative genomics analysis of photolithotrophs and chemoorganotrophs.
- Review of physiological data on growth rates and cellular composition.
- Examination of evolutionary pressures related to photosynthesis and atmospheric composition.
Main Results:
- Photolithotrophs possess larger genomes and slower growth rates compared to chemoorganotrophs, attributed to resource allocation for the photosynthetic apparatus.
- Photosynthesis, especially oxygenic, presents risks such as reactive oxygen species (ROS) formation and sensitivity to blue light.
- Atmospheric oxygenation necessitated defenses against ROS and influenced nutrient availability, driving evolutionary adaptations like differential codon usage.
Conclusions:
- Photolithotrophy entails trade-offs, including slower growth and increased cellular investment in light-harvesting machinery.
- Adaptations to oxygenic photosynthesis and environmental changes are evident in genome structure and gene expression.
- Further research is needed to fully understand DNA repair, protein turnover, and resource management in photolithotrophs.
Keywords:
gene numbergenome sizegrowth ratehighly expressed proteinsoxygenic photosynthesisultraviolet radiationMore Related Videos
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