A Localized Complex of Two Protein Oligomers Controls the Orientation of Cell Polarity

@article{Perez2017ALC,
  title={A Localized Complex of Two Protein Oligomers Controls the Orientation of Cell Polarity},
  author={Adam M. Perez and Thomas H. Mann and Keren Lasker and Daniel Ahrens and Michael R. Eckart and Lucy Shapiro},
  journal={mBio},
  year={2017},
  volume={8}
}
ABSTRACT Signaling hubs at bacterial cell poles establish cell polarity in the absence of membrane-bound compartments. In the asymmetrically dividing bacterium Caulobacter crescentus, cell polarity stems from the cell cycle-regulated localization and turnover of signaling protein complexes in these hubs, and yet the mechanisms that establish the identity of the two cell poles have not been established. Here, we recapitulate the tripartite assembly of a cell fate signaling complex that forms… 
A circuit of protein-protein regulatory interactions enables polarity establishment in a bacterium
TLDR
This work has characterized the regulatory interactions between three scaffolding proteins and revealed that the scaffold protein PodJ functions as a central mediator for organizing the new cell signaling hub, including promoting bipolarization of the central developmental scaffolding protein PopZ.
Selective sequestration of signaling proteins in a membraneless organelle reinforces the spatial regulation of asymmetry in Caulobacter crescentus
TLDR
This work demonstrates how nanoscale protein assemblies can modulate signal propagation with fine spatial resolution, and that in Caulobacter, this modulation serves to reinforce asymmetry and differential cell fate of the two daughter cells.
Phospho-signal flow from a pole-localized microdomain spatially patterns transcription factor activity
TLDR
This study revealed that the microdomain is selectively permeable, and that each protein in the signaling pathway that activates the cell fate transcription factor CtrA is sequestered and uniformly concentrated within the micro domain or its proximal membrane.
Scaffold-scaffold interactions regulate cell polarity in a bacterium
TLDR
Segregation of PopZ protein at the old pole and recruitment of newly translated PopZ at the new pole via the PodJ scaffold ensures stringent inheritance and maintenance of the polarity axis within dividing C. crescentus cells.
Construction of intracellular asymmetry and asymmetric division in Escherichia coli
TLDR
It is demonstrated that the oligomeric PopZ from Caulobacter crescentus can serve as a robust polarized scaffold to functionalize RNA polymerase, and the coupled oligomerization and restriction in diffusion may be a strategy for generating a spatial gradient for asymmetric cell division.
Intrinsically disordered bacterial polar organizing protein Z, PopZ, interacts with protein binding partners through an N-terminal Molecular Recognition Feature.
TLDR
The results show that a partially structured Molecular Recognition Feature (MoRF) within an intrinsically disordered domain of PopZ contributes to the assembly of polar microdomains, revealing a structural basis for complex network assembly in Alphaproteobacteria that is analogous to those formed by intrinsically dis ordered hub proteins in other kingdoms.
Regulation of a bacterial histidine kinase by a phase separating scaffolding protein
TLDR
A model where PodJ biomolecular condensate formation regulates the localization and activity of the cell fate determining kinase PleC is supported, where full-length PodJL regulates PleC-CcaS signaling, while a truncated PodJs could not regulate signaling activity.
Generating asymmetry in a changing environment: cell cycle regulation in dimorphic alphaproteobacteria
TLDR
In this review, the current knowledge of the CtrA pathway is summarized and how it has evolved to regulate the cell cycle of morphologically distinct alphaproteobacteria is discussed.
Polar Localization Hub Protein PopZ Restrains Adaptor-Dependent ClpXP Proteolysis in Caulobacter crescentus
TLDR
It is found that CtrA degradation is enhanced in cells lacking polar localization due to loss of PopZ, and this study offers evidence that supports an alternative model to explain how localization might influence protein degradation.
...
...

References

SHOWING 1-10 OF 57 REFERENCES
Oligomerization and higher‐order assembly contribute to sub‐cellular localization of a bacterial scaffold
TLDR
PopZ undergoes multiple orders of self‐assembly, and the formation of an interconnected superstructure is a key feature of polar organization in Caulobacter.
The dynamic interplay between a cell fate determinant and a lysozyme homolog drives the asymmetric division cycle of Caulobacter crescentus.
TLDR
The dynamic interplay between SpmX and DivK is at the heart of the molecular circuitry that sustains the Caulobacter developmental cycle.
Caulobacter PopZ forms a polar subdomain dictating sequential changes in pole composition and function
TLDR
It is proposed that pole‐specific control of PopZ function co‐ordinates polar development and cell cycle progression by enabling independent assembly and tethering activities at the two cell poles.
Assembly of the Caulobacter cell division machine
TLDR
Differences in divisome assembly among Caulobacter and other bacteria are revealed that establish a framework for identifying aspects of bacterial cytokinesis that are widely conserved from those that are more variable.
Modularity and determinants of a (bi-)polarization control system from free-living and obligate intracellular bacteria
TLDR
It is shown that ZitP regulates cytokinesis and the localization of ParB and PopZ, targeting PopZ independently of the previously known binding sites for its client proteins.
...
...