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Measurement of macromolecular crowding in rhodobacter sphaeroides under different growth conditions

Abstract:
The bacterial cytoplasm is a very crowded environment, and changes in crowding are thought to have an impact on cellular processes including protein folding, molecular diffusion and complex formation. Previous studies on the effects of crowding have generally compared cellular activity after imposition of stress. In response to different light intensities, in unstressed conditions, Rhodobacter sphaeroides changes the number of 50-nm intracytoplasmic membrane (ICM) vesicles, with the number varying from a few to over a thousand per cell. In this work, the effects of crowding induced by ICM vesicles in photoheterotrophic R. sphaeroides were investigated using a fluorescence resonance energy transfer (FRET) sensor and photoactivated localization microscopy (PALM). In low light grown cells where the cytoplasm has large numbers of ICM vesicles, the FRET probe adopts a more condensed conformation, resulting in higher FRET ratio readouts compared to high light cells with fewer ICM vesicles. The apparent diffusion coefficients of different sized proteins, PAmCherry, PAmCherry-CheY6, and L1-PAmCherry, measured via PALM showed that diffusion of protein molecules >27 kDa decreased as the number of ICM vesicles increased. In low light R. sphaeroides where the crowding level is high, protein molecules were found to diffuse more slowly than in aerobic and high light cells. This suggests that some physiological activities might show different kinetics in bacterial species whose intracellular membrane organization can change with growth conditions.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1128/mbio.03672-21

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MSD
Department:
Biochemistry
Oxford college:
Merton College
Role:
Author
ORCID:
0000-0003-4983-9731


Publisher:
American Society for Microbiology
Journal:
mBio More from this journal
Volume:
13
Issue:
1
Article number:
e03672-21
Publication date:
2022-01-25
Acceptance date:
2021-12-21
DOI:
EISSN:
2150-7511


Language:
English
Keywords:
Pubs id:
1226838
Local pid:
pubs:1226838
Deposit date:
2021-12-23

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