Abstract
Cyanobacteria are photosynthetic prokaryotes that make major contributions to the production of the oxygen in the Earth atmosphere. The photosynthetic machinery in cyanobacterial cells is housed in flattened membrane structures called thylakoids. The structural organization of cyanobacterial cells and the arrangement of the thylakoid membranes in response to environmental conditions have been widely investigated. However, there is limited knowledge about the internal dynamics of these membranes in terms of their flexibility and motion during the photosynthetic process. We present a direct observation of thylakoid membrane undulatory motion in vivo and show a connection between membrane mobility and photosynthetic activity. High-resolution inelastic neutron scattering experiments on the cyanobacterium Synechocystis sp. PCC 6803 assessed the flexibility of cyanobacterial thylakoid membrane sheets and the dependence of the membranes on illumination conditions. We observed softer thylakoid membranes in the dark that have three-to four fold excess mobility compared to membranes under high light conditions. Our analysis indicates that electron transfer between photosynthetic reaction centers and the associated electrochemical proton gradient across the thylakoid membrane result in a significant driving force for excess membrane dynamics. These observations provide a deeper understanding of the relationship between photosynthesis and cellular architecture.
Original language | English |
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Article number | 19627 |
Journal | Scientific Reports |
Volume | 6 |
DOIs | |
State | Published - Jan 21 2016 |
Funding
Neutron beam time for this research has been allocated by the Jülich Center for Neutron Science, JCNS1, Jülich Forschungszentrum GmbH, Germany, outstation to the Spallation Neutron Source (SNS), Oak Ridge, TN. The authors acknowledge Malcolm Cochran for the construction of the illumination setup and technical support during measurements, Dr. Piotr Zolnierczuk for providing automatic control of the illumination setup and software support during measurements, Rhonda Moody and Dr. Kevin Weiss from SNS biochemistry lab support, William B. O’Dell for assistance with Small-Angle Neutron Scattering (SANS) data, Dr. Jonathan Nickels, Prof. Dr. Dieter Richter and Dr. Michael Monkenbusch for discussion on data interpretation. The generation of neutrons for this research at ORNL’s Spallation Neutron Source and High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, Office of Biological and Environmental Research, U.S. Department of Energy. M.L., H.B.P., H.O.N. and V.S.U. were supported by the Photosynthetic Antenna Research Center (PARC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and Office of Basic Energy Sciences, under Award Number DE-SC 0001035.
Funders | Funder number |
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Photosynthetic Antenna Research Center | |
Scientific User Facilities Division | |
U.S. Department of Energy | |
Office of Science | DE-SC 0001035 |
Office of Science | |
Basic Energy Sciences | |
Biological and Environmental Research |