Title: Influence of Chemically Disrupted Photosynthesis on Cyanobacterial Thylakoid Dynamics in Synechocystis sp. PCC 6803

Abstract

The photosynthetic machinery of the cyanobacterium Synechocystis sp. PCC 6803 resides in flattened membrane sheets called thylakoids, situated in the peripheral part of the cellular cytoplasm. Under photosynthetic conditions these thylakoid membranes undergo various dynamical processes that could be coupled to their energetic functions. Using Neutron Spin Echo Spectroscopy (NSE), we have investigated the undulation dynamics of Synechocystis sp. PCC 6803 thylakoids under normal photosynthetic conditions and under chemical treatment with DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea), an herbicide that disrupts photosynthetic electron transfer. Our measurements show that DCMU treatment has a similar effect as dark conditions, with differences in the undulation modes of the untreated cells compared to the chemically inhibited cells. We found that the disrupted membranes are 1.5-fold more rigid than the native membranes during the dark cycle, while in light they relax approximately 1.7-fold faster than native and they are 1.87-fold more flexible. The strength of the herbicide disruption effect is characterized further by the damping frequency of the relaxation mode and the decay rate of the local shape fluctuations. In the dark, local thicknesses and shape fluctuations relax twice as fast in native membranes, at 17% smaller mode amplitude, while in light the decay rate of local fluctuations ismore » 1.2-fold faster in inhibited membranes than in native membranes, at 56% higher amplitude. The disrupted electron transfer chain and the decreased proton motive force within the lumenal space partially explain the variations observed in the mechanical properties of the Synechocystis membranes, and further support the hypothesis that the photosynthetic process is tied to thylakoid rigidity in this type of cyanobacterial cell.« less

Authors:

Stingaciu, Laura-Roxana  ^[1];

• Search DOE PAGES for author "Stingaciu, Laura-Roxana"
• Search DOE PAGES for ORCID "0000-0003-2696-5233"

O’Neill, Hugh M.  ^[1];

• Search DOE PAGES for author "O’Neill, Hugh M."
• Search DOE PAGES for ORCID "0000-0003-2966-5527"

Liberton, Michelle ^[2]; Pakrasi, Himadri B. ^[2]; Urban, Volker S.  ^[1]

• Search DOE PAGES for author "Urban, Volker S."
• Search DOE PAGES for ORCID "0000-0002-7962-3408"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Washington Univ., St. Louis, MO (United States)

Publication Date:

Fri Apr 05 00:00:00 EDT 2019

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Photosynthetic Antenna Research Center (PARC); Washington Univ., St. Louis, MO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1566625

Grant/Contract Number:  

SC0001035

Resource Type:

Accepted Manuscript

Journal Name:

Scientific Reports

Additional Journal Information:

Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2045-2322

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; solar (fuels); photosynthesis (natural and artificial); biofuels (including algae and biomass); bio-inspired; charge transport; membrane; synthesis (novel materials); synthesis (self-assembly)