Figures
γ-proteobacteria eject their polar flagella under nutrient depletion, retaining flagellar motor relic structures
In the face of starvation, bacteria must minimize their energy use. This study by Ferreira et al. describes the unexpected finding that some bacteria take the drastic measure of ejecting their flagella in response to nutrient deficiency. Bacteria continually assemble flagella as propellers, spun by rotary motors embedded in the cell, but rotation and assembly can consume up to 3% of a bacterium's energy. Here, electron cryo-tomography reveals partial flagellar motors in bacterial cells that are rare when nutrients were abundant but become common when nutrients were scarce. The authors provide evidence that these structures are relics of motors whose flagella have been ejected. Curiously, flagellar relics — which would otherwise be open portals through which the contents of the bacterial periplasm could leak — are plugged by an unidentified protein, presumably as a preservation measure. The image shows cutaway (left) and surface renderings (right) of cryo-tomograms of the intact polar flagellar motor (top) from Plesiomonas shigelloides, and the polar relic structure (bottom). Note the plug (pale green).
Image Credit: 10.1371/journal.pbio.3000165
Citation: (2019) PLoS Biology Issue Image | Vol. 17(3) March 2019. PLoS Biol 17(3): ev17.i03. https://doi.org/10.1371/image.pbio.v17.i03
Published: March 31, 2019
Copyright: © 2019 . This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
In the face of starvation, bacteria must minimize their energy use. This study by Ferreira et al. describes the unexpected finding that some bacteria take the drastic measure of ejecting their flagella in response to nutrient deficiency. Bacteria continually assemble flagella as propellers, spun by rotary motors embedded in the cell, but rotation and assembly can consume up to 3% of a bacterium's energy. Here, electron cryo-tomography reveals partial flagellar motors in bacterial cells that are rare when nutrients were abundant but become common when nutrients were scarce. The authors provide evidence that these structures are relics of motors whose flagella have been ejected. Curiously, flagellar relics — which would otherwise be open portals through which the contents of the bacterial periplasm could leak — are plugged by an unidentified protein, presumably as a preservation measure. The image shows cutaway (left) and surface renderings (right) of cryo-tomograms of the intact polar flagellar motor (top) from Plesiomonas shigelloides, and the polar relic structure (bottom). Note the plug (pale green).
Image Credit: 10.1371/journal.pbio.3000165