Subcellular organization in eukaryotic cells is largely governed by linear motor proteins. In bacteria, where
linear motors are absent, a widespread family of ParA/MinD (A/D) ATPases are responsible for spatially
organizing an array of genetic- and protein-based cellular cargos, the majority of which are unstudied. Of the
well-studied examples, ParA ATPases segregate chromosomes and MinD ATPases position cell division in
bacteria. Less studied is the growing list of A/D ATPases that spatially organize diverse protein-based cellular
cargos, such as bacterial microcompartments (BMCs), flagella, chemotaxis arrays, and conjugation machinery.
The long term goal is to understand how A/D ATPases drive and coordinate the positioning of such a diverse
set of fundamental cellular cargos across bacteria, including those important to human health.
Preliminary data from the project team shows that over a third of all bacteria encode multiple A/D ATPases.
Among these bacteria are several human pathogens. The project team identified a nonpathogenic and
experimentally tractable bacterium, Halothiobacillus neapolitanus, encoding six A/D ATPases, where each
ATPase is dedicated to the positioning of a specific cellular cargo: the chromosome, the divisome, the
carboxysome BMC, the flagellum, the chemotaxis array, and the conjugation machinery. The goal for the next
five years is to use H. neapolitanus as an ideal model for probing mechanistic commonality, variation, and
coordination, among the most widespread ATPase family used in the subcellular organization of bacterial cells.
These advancements are important for human health because several of the bacteria encoding multiple
A/D ATPases have associated cargos involved in pathogenesis. The overall objective here is to determine how
multiple A/D ATPases coordinately function to spatially organize diverse cellular cargos. The central
hypothesis is that in bacteria encoding multiple A/D ATPases, each ATPase is dedicated to the positioning of a
specific cellular cargo, with specificity provided by an adaptor protein that links the cargo to its cognate
ATPase, and that these positioning reactions are spatiotemporally coordinated. The rationale for the proposed
research is that by determining how multiple A/D ATPases coordinately function within a single bacterial
organism the project team will define the general mode of transport among this ATPase family, determine how
the mechanism is altered for disparate cargos, and identify the specificity determinants for each cargo. The
proposed research is creative and original because it has only recently been appreciated that protein-based
organelles are prevalent across the bacterial world, making organelle trafficking in bacteria a new field of study.
The project team will leverage this knowledge in the design of minimal and modular positioning systems for
the faithful inheritance of cellular cargos in heterologous bacteria for synthetic biology approaches and
biomedical application. Finally, the project team anticipates these findings will inform identification of novel
positioning mechanisms and antibiotic targets important for bacterial pathogens.