Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
142
88-POS
Board 44
The Modulation of Min and Nucleoid Occlusion Systems in Escherichia Coli
Wei-Chen Tsai
1
, Jie-Pan Shen
1
, Yi-Ren Chang
2
, Chia-Fu Chou
1
.
1
Academia Sinica, Taipei, Taiwan,
2
National Taiwan Normal University, Taipei, Taiwan.
Spatial control of prokaryotic cell division is solely achieved by directing Z-ring assembly at
specified position. In E. coli, Min oscillation, together with nucleoid occlusion (NO), destabilize
Z-ring in the regions away from midcell to ensure faithful septation. Min oscillation, driven by
MinD-ATPase hydrolysis via MinE activation on the membrane, establishes a time-averaged
MinCD gradient to yield a pronounced minimum of MinC’s inhibition on Z-ring at midcell.
Because early-division proteins ZipA and ZapA/B, along with FtsZ, assemble into complexes
that counter-oscillate with Min system, stable oscillations to suppress Z-ring assembly is
expected to allow MinC residing in each polar zone longer than the half-time of FtsZ turnover.
Even though Min oscillation has been displayed by synthetic systems, it’s unclear the interplays
of Min proteins and compartment geometry are sufficient to bolster oscillation stability in vivo.
Here the Min-nucleoid interaction is reported as the physicochemical element missing in
previous researches to commit stable Min oscillation in vivo. We found, compared with
unperturbed cells, Min oscillation in anucleate and nucleoid-perturbed cells was deviated up to a
quarter-cycle, but the frequency was higher in anucleate and lower in nucleoid-perturbed cells.
Enhanced stability and lowered frequency were observed in cells expressing excess NO factor
SlmA. Further, cell filamentation by excess SlmA and associated DNA-binding sites was
antagonized by overproduced Min proteins, and as such asymmetric septation was enabled to
reduce cell size. Our results reveal an unanticipated role of the nucleoid in the modulation of
frequency and stability of Min system; moreover, SlmA is indicated to facilitate such
modulations, potentially via directly interacting with Min system. we propose a fresh perspective
that frequency modulation of Min system is mediated via the act of nucleoid-associated factor;
and envision a model of Min-nucleoid interaction.