THESIS
2019
xi, 73 pages : illustrations (some color) ; 30 cm
Abstract
Super-resolution imaging nourished remarkable breakthroughs in deciphering the proteins
subcellular organization in diverse organisms. However, its application in photosynthetic cells
had been limited, until our recent development of a photobleaching method that can remove the
autofluorescence background in photosynthetic cells, thereby enable the three-dimensional
super-resolution imaging by STORM with the resolution of ~10 nm. Marine cyanobacteria are
the dominant photosynthetic organisms on Earth, who contribute a substantial part in global
carbon cycle. Their circadian rhythmic metabolism has been intensively studied, but few have
been revealed about the related protein organization dynamics by imaging studies.
In this study, first we demonstrated the applicability of our ph...[
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Super-resolution imaging nourished remarkable breakthroughs in deciphering the proteins
subcellular organization in diverse organisms. However, its application in photosynthetic cells
had been limited, until our recent development of a photobleaching method that can remove the
autofluorescence background in photosynthetic cells, thereby enable the three-dimensional
super-resolution imaging by STORM with the resolution of ~10 nm. Marine cyanobacteria are
the dominant photosynthetic organisms on Earth, who contribute a substantial part in global
carbon cycle. Their circadian rhythmic metabolism has been intensively studied, but few have
been revealed about the related protein organization dynamics by imaging studies.
In this study, first we demonstrated the applicability of our photobleaching method to
remove the 750-nm autofluorescence and STORM imaging in multiple cyanobacteria rains.
Moreover, we discovered the possibility of photobleaching the 647-nm fluorescence in
Prochlorococcus MED4. Together with the 750-nm channel, it suggests the availability of two-channel
labelling and super-resolution imaging in photosynthesis cells without compromising
the resolution. It will strengthen our ability of investigating the protein organizations and
interactions in cyanobacteria.
Afterwards, by STORM imaging, we characterized the day-night organization of
cyanobacterial circadian oscillator KaiC in Prochlorococcus NATL2A. Regardless of the lack
of kaiA and cikA, which are essential to maintain the diel dynamic organization of KaiC in Synechococcus, Prochlorococcus was found to retain the KaiC organization dynamics. That is,
KaiC was aggregated as foci at night, while in the day it was diffusely distributed inside the
cell. Furthermore, from the cyanophage P-SSM2 infection of NATL2A at night, we reported
the first evidence that phage infection can disturb the organization of circadian clock protein,
which reversed the nighttime organization of KaiC to the daytime pattern. Our results shed new
light on the manipulation viruses can make during the infection, possibly for a better utilization
of the host’s intracellular metabolic environment.
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