Organization of the Bacterial Cell and Organelles

Despite being small unicellular organisms, bacteria have the ability to organize their cellular architecture and spatially regulate synthesis of organelles and macromolecular complexes essential for many biological activities. In addition, the synthesis of certain macromolecular complexes and organelles are numerically regulated so that bacteria only produce a level ideal for the organisms.

Monitoring the localization of a flagellar protein in C. jejuni

Flagellar motors in polarly-flagellated bacteria are excellent examples of organelles that are spatially and numerically regulated in specific bacterial species. Unlike in peritrichous bacteria where many flagellar motors are dispersed on the cell surface, polarly-flagellated bacteria are genetically programmed to only produce one or a few flagella specifically at the poles of the bacterial cell.

Campylobacter jejuni is a polarly-flagellated bacteria that produces amphitrichous flagella, characterized by a single flagellum at both poles of the bacterium. We are investigating how the bacterium limits each pole to a single flagellum and mediates the targeting of flagellar proteins to the poles so that flagellar motors are only produced at these locations. We expect that many of our findings will be applicable to other polarly-flagellated bacterial species.

Impact of FlhG on control of flagellar number and symmetrical division
Inhibition of division by an FlhG mutant

We are focusing on two proteins, the FlhF GTPase and the FlhG ATPase that are common to many polar flagellates and appear to facilitate the spatial and numerical regulation of flagellar biogenesis in these bacteria. Furthermore, we have discovered that FlhG and flagella also impacts the ability of C. jejuni to divide properly. This finding indicates that the flagellum influences the spatial regulation of the divisome, which is required for proper symmetrical division to generate viable daughter cells.

We expect our work to continue to contribute to new mechanisms by which bacteria organize their cell bodies and mediate spatial and numerical regulation of macromolecular complexes that are essential for many biological activities.

Relevant Publications