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Bathy phytochromes in rhizobial soil bacteria
Gregor Rottwinkel1, Inga Oberpichler, Tilman Lamparter
1Institute of Botany, Faculty of Chemistry and Biosciences, Karlsruhe Institute of Technology, Kaiserstr. 2, 76131 Karlsruhe, Germany.
Journal of Bacteriology
|August 3, 2010
Summary
Bathy phytochromes, a type of bacterial photoreceptor with a Pfr ground state, are widespread in Rhizobiales bacteria. These findings suggest bathy phytochromes are soil light adaptations and evolved into complex histidine kinases.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Phytochromes are biliprotein photoreceptors in plants, bacteria, and fungi.
- Prototypical phytochromes convert from red-absorbing Pr to far-red-absorbing Pfr form upon light exposure.
- Some bacterial phytochromes exhibit dark conversion from Pr to Pfr, possessing a Pfr ground state.
Purpose of the Study:
- Investigate the distribution and properties of bacterial phytochromes, particularly those with a Pfr ground state (bathy phytochromes).
- Determine the spectral properties and dark conversion direction of phytochromes in various Rhizobiales species.
- Explore the evolutionary origins of phytochromes with response regulator domains.
Main Methods:
- In vivo spectral property measurements.
- Analysis of phytochrome dark conversion direction.
- Phylogenetic studies of phytochrome protein sequences.
Main Results:
- Bathy phytochromes are widely distributed among bacteria in the order Rhizobiales.
- Agrobacterium tumefaciens C58 has one bathy phytochrome and another with Pfr to Pr dark conversion.
- Rhizobium and Azorhizobium species possess single bathy phytochromes, while Xanthobacter autotrophicus Py2 has a single Pfr to Pr converting phytochrome.
- Phylogenetic analysis indicates that phytochromes with response regulator domains evolved from bathy phytochrome progenitors.
Conclusions:
- Bathy phytochromes are likely adaptations to soil light environments.
- The diversity of phytochrome types within Rhizobiales highlights varied light sensing strategies.
- Bathy phytochromes represent an ancestral form that gave rise to more complex light-regulated systems.
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