Frequency modulation of the Min-protein oscillator by nucleoid-associated factors in Escherichia coli

Abstract

In E. coli, the Min-protein oscillator, together with the nucleoid occlusion (NO), destabilizes the Z-ring assembly away from the midcell to ensure faithful septation. These two inhibitory pathways are thought to be working independently for division site placement. Even though the Min-protein oscillator has been displayed by synthetic minimal systems, it is unclear the interplays of Min proteins and compartment geometry are sufficient to bolster oscillation stability in vivo. By probing if NO plays a role in the Min oscillation, we study the oscillation frequency in the anucleate and nucleoid-perturbed cells. Surprisingly, we found that the oscillation periods of the Min-protein oscillators were seriously deviated in the anucleate and nucleoid-perturbed cells, but the oscillation frequency either went up in the anucleate or down in the nucleoid-perturbed cells. Intriguingly, enhanced stability and reduced frequency were observed in the cells expressing the NO factor SlmA higher than the native level. Our results reveal an unanticipated role of the nucleoid in modulating the frequency and stability of Min-protein system. SlmA is indicated to facilitate such modulations, potentially via directly interacting with the Min-protein system. A fresh perspective is suggested that frequency modulation of Min-protein oscillator is mediated via the act of nucleoid-associated factors.