Selective sequestration of signalling proteins in a membraneless organelle reinforces the spatial regulation of asymmetry in Caulobacter crescentus

Keren Lasker, Lexy von Diezmann, Xiaofeng Zhou, Daniel G. Ahrens, Thomas H. Mann, W. E. Moerner, Lucy Shapiro

Research output: Contribution to journalLetterpeer-review

59 Scopus citations

Abstract

Selective recruitment and concentration of signalling proteins within membraneless compartments is a ubiquitous mechanism for subcellular organization1–3. The dynamic flow of molecules into and out of these compartments occurs on faster timescales than for membrane-enclosed organelles, presenting a possible mechanism to control spatial patterning within cells. Here, we combine single-molecule tracking and super-resolution microscopy, light-induced subcellular localization, reaction-diffusion modelling and a spatially resolved promoter activation assay to study signal exchange in and out of the 200 nm cytoplasmic pole-organizing protein popZ (PopZ) microdomain at the cell pole of the asymmetrically dividing bacterium Caulobacter crescentus4–8. Two phospho-signalling proteins, the transmembrane histidine kinase CckA and the cytoplasmic phosphotransferase ChpT, provide the only phosphate source for the cell fate-determining transcription factor CtrA9–18. We find that all three proteins exhibit restricted rates of entry into and escape from the microdomain as well as enhanced phospho-signalling within, leading to a submicron gradient of activated CtrA-P19 that is stable and sublinear. Entry into the microdomain is selective for cytosolic proteins and requires a binding pathway to PopZ. Our 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.

Original languageEnglish (US)
Pages (from-to)418-429
Number of pages12
JournalNature Microbiology
Volume5
Issue number3
DOIs
StatePublished - Mar 1 2020
Externally publishedYes

Bibliographical note

Funding Information:
We thank J.W. Kern for help with plasmid design and construction, M.D. Melfi for providing the RT–qPCR protocol, A. Lovell and M.R. Eckart at the Stanford Protein and Nucleic Acid Facility for support in using MySeq and RT–qPCR and for running the surface plasmon resonance experiments, J.M. Schrader for sharing unpublished data on mRNA half-life in Caulobacter, A. Olson and the Stanford Neuroscience Microscopy Service (supported by grant no. NIH NS069375) for providing equipment for and assistance with the photobleaching experiments and A.H. Squires for critical feedback on the manuscript. We also thank H.H. McAdams for helpful discussions on the modelling of signal transduction and all members of the Shapiro and Moerner laboratories for helpful discussions throughout the project. We acknowledge support from the Gordon and Betty Moore Function (award no. GBMF 2550.03) to the Life Sciences Research Foundation (to K.L.), the Weizmann Institute of Science National Postdoctoral Award Program for Advancing Women in Science (to K.L.) and from the National Institute of General Medical Sciences of the National Institutes of Health under award nos. T32GM007276 to T.H.M, R01-GM086196 to W.E.M. and L.S., R35-GM118067 to W.E.M. and R35-GM118071 to L.S. L.S. is a Chan Zuckerberg Biohub Investigator. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Publisher Copyright:
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.

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