Fremyella diplosiphon

Fremyella diplosiphon is a freshwater filamentous cyanobacterium known for chromatic acclimation (CA), dramatic shifts between green and red phenotypes due to ambient light color changes. The color shifts within F. diplosiphon filaments during CA reflect changes in the chromoproteins of photosynthetic light-harvesting antennae. In red light, the chromoprotein phycocyanin is produced, absorbing red light and making cells blue-green. In green light the chromoprotein phycoerythrin is made, which absorbs green light and makes cells red. Chromoprotein production is controlled by the phytochrome superfamily photoreceptors RcaE and DpxA. Both are light-regulated histidine kinases of two-component systems. RcaE is activated in red light and inactivated in green light, while DpxA is activated in yellow and inactivated in teal light. The coordinate regulation of light-harvesting antennae biogenesis reveals the complex interactions between phytochrome family photoreceptors in bacteria. View Large Image Figure Viewer Download Hi-res image Download (PPT) View Large Image Figure Viewer Download Hi-res image Download (PPT