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 C. tepidum grows slower and incorporates fewer 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 homologs with smaller side chains, (c) blue-shifted Q y absorption maxima, and (d) a sigmoid-shaped circular dichroism 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.
| Original language | English |
|---|---|
| Pages (from-to) | 1346-1356 |
| Number of pages | 11 |
| Journal | Biophysical Journal |
| Volume | 105 |
| Issue number | 6 |
| DOIs | |
| State | Published - Sep 17 2013 |
Funding
The authors thank Dr. Xing Xu and Dr. Sun W. Tam at Nuclea Biotechnologies for assisting mass spectral measurements and Professor Gang Han at the University of Massachusetts Medical School for the access to his dynamic light-scattering instrument. Bio-SANS CG-3 is a resource of the Center for Structural Molecular Biology at Oak Ridge National Laboratory supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Project ERKP291. Work in the laboratory of H.A.F. was supported by grants from the National Science Foundation (MCB-1243565) and the University of Connecticut Research Foundation. A.A.-G. and J.H. acknowledge support from the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and Office of Basic Energy Sciences under Award DESC0001088. A.A.-G. and S.K.S. acknowledge Defense Threat Reduction Agency Grant HDTRA1-10-1-0046. A.A.-G. also thanks the Corning Foundation for its generous support. J.K.T. is supported by start-up funds and faculty development fund from Clark University.
| Funders | Funder number |
|---|---|
| Center for Excitonics | |
| Clark University | |
| Office of Basic Energy Sciences | DESC0001088 |
| Office of Biological and Environmental Research Project | ERKP291 |
| University of Connecticut Research Foundation | |
| National Science Foundation | MCB-1243565 |
| National Science Foundation | |
| U.S. Department of Energy | |
| Directorate for Biological Sciences | 1243565 |
| Directorate for Biological Sciences | |
| Office of Science |