1. Temperature and Carbon Assimilation Regulate the Chlorosome Biogenesis in Green Sulfur Bacteria
- Author
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Joonsuk Huh, Harry A. Frank, Miriam M. Enriquez, Volker S. Urban, Joseph Kuo-Hsiang Tang, Semion K. Saikin, Alán Aspuru-Guzik, and Sai Venkatesh Pingali
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Models, Molecular ,0106 biological sciences ,Optical Phenomena ,Biophysics ,FOS: Physical sciences ,chemistry.chemical_element ,Chlorosome ,Biology ,01 natural sciences ,Chlorobi ,03 medical and health sciences ,chemistry.chemical_compound ,Bacterial Proteins ,Carbon assimilation ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Carbon source ,Physics - Biological Physics ,Bacteriochlorophylls ,030304 developmental biology ,2. Zero hunger ,0303 health sciences ,Condensed Matter - Mesoscale and Nanoscale Physics ,Temperature ,biology.organism_classification ,Carbon ,Biochemistry ,chemistry ,Cell Biophysics ,Biological Physics (physics.bio-ph) ,Green sulfur bacteria ,Photosynthetic bacteria ,Bacteriochlorophyll ,Biogenesis ,010606 plant biology & botany - Abstract
Green photosynthetic bacteria adjust the structure and functionality of the chlorosome - the light absorbing antenna complex - in response to environmental stress factors. The chlorosome is a natural self-assembled aggregate of bacteriochlorophyll (BChl) molecules. In this study we report the regulation of the biogenesis of the Chlorobaculum tepidum chlorosome by carbon assimilation in conjunction with temperature changes. Our studies indicate that the carbon source and thermal stress culture of Cba. tepidum grows slower and incorporates less BChl c in the chlorosome. Compared with the chlorosome from other cultural conditions we investigated, the chlorosome from the carbon source and thermal stress culture displays: (a) smaller cross-sectional radius and overall size; (b) simplified BChl c homologues with smaller side chains; (c) blue-shifted Qy absorption maxima and (d) a sigmoid-shaped circular dichroism (CD) spectra. Using a theoretical model we analyze how the observed spectral modifications can be associated with structural changes of BChl aggregates inside the chlorosome. Our report suggests a mechanism of metabolic regulation for chlorosome biogenesis., 32 pages, 14 figures
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