Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2021 Apr 30:8:682967.
doi: 10.3389/fmolb.2021.682967. eCollection 2021.

The Protein Quality Control Network in Caulobacter crescentus

Affiliations
Review

The Protein Quality Control Network in Caulobacter crescentus

Kristen Schroeder et al. Front Mol Biosci. .

Abstract

The asymmetric life cycle of Caulobacter crescentus has provided a model in which to study how protein quality control (PQC) networks interface with cell cycle and developmental processes, and how the functions of these systems change during exposure to stress. As in most bacteria, the PQC network of Caulobacter contains highly conserved ATP-dependent chaperones and proteases as well as more specialized holdases. During growth in optimal conditions, these systems support a regulated circuit of protein synthesis and degradation that drives cell differentiation and cell cycle progression. When stress conditions threaten the proteome, most components of the Caulobacter proteostasis network are upregulated and switch to survival functions that prevent, revert, and remove protein damage, while simultaneously pausing the cell cycle in order to regain protein homeostasis. The specialized physiology of Caulobacter influences how it copes with proteotoxic stress, such as in the global management of damaged proteins during recovery as well as in cell type-specific stress responses. Our mini-review highlights the discoveries that have been made in how Caulobacter utilizes its PQC network for regulating its life cycle under optimal and proteotoxic stress conditions, and discusses open research questions in this model.

Keywords: bacterial development; cell cycle; chaperone; holdase; protease; protein quality control.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Roles of the Caulobacter crescentus PQC network in cell cycle progression and development. (A) The asymmetric life cycle of Caulobacter. Points where mechanisms have been identified where specific PQC proteins contribute to cell cycle progression are indicated with colored arrows. (B) Specific tasks of individual PQC network proteins in development and cell cycle progression during optimal conditions. Client proteins are indicated in circles where they are known, and by question marks where additional substrates have yet to be identified. Holdase cycling is indicated with gray circular arrows, and degradation with dashed lines. Blue dashed arrows indicate points of interaction between PQC network proteins. Membrane and DNA images created with Biorender (Biorender.com).
FIGURE 2
FIGURE 2
Stress response tasks of the Caulobacter crescentus PQC network. (A) Heat stress induces unfolding of the susceptible proteome, and unfolded proteins (gray squiggles) are incorporated into insoluble protein aggregates (gray dots). Known interactions during stress are indicated by protein name in colored circles. DnaKJ/E, ClpB, and GroESL participate in protein refolding and disaggregation. The small heat shock proteins organize unfolded proteins. ClpAP and Lon participate in degradation of unfolded proteins, in addition to regulatory roles. The proteases FtsH and HslUV are upregulated in response to proteotoxic stress, but it is unknown whether they contribute to degradation of unfolded proteins or regulatory substrates. (B) Oxidative stress results in oxidation of proteins and draining of the hydrotrope ATP, which can influence folding state. The holdase CnoX interacts and is capable of reducing disulfide groups of proteins, and protects them from aggregation until active GroESL and/or DnaKJ/E are available to refold these proteins. Membrane and DNA images created with Biorender (Biorender.com).

Similar articles

Cited by

References

    1. Aakre C. D., Phung T. N., Huang D., Laub M. T. (2013). A bacterial toxin inhibits DNA replication elongation through a direct interaction with the β sliding clamp. Mol. Cell 52 617–628. 10.1016/j.molcel.2013.10.014 - DOI - PMC - PubMed
    1. Abel S., Chien P., Wassmann P., Schirmer T., Kaever V., Laub M. T., et al. (2011). Regulatory cohesion of cell cycle and cell differentiation through interlinked phosphorylation and second messenger networks. Mol. Cell 43 550–560. 10.1016/j.molcel.2011.07.018 - DOI - PMC - PubMed
    1. Ackermann M., Stearns S. C., Jenal U. (2003). Senescence in a bacterium with asymmetric division. Science 300:1920. 10.1126/science.1083532 - DOI - PubMed
    1. Avedissian M., Gomes S. L. (1996). Expression of the groESL operon is cell-cycle controlled in Caulobacter crescentus. Mol. Microbiol. 19 79–89. 10.1046/j.1365-2958.1996.347879.x - DOI - PubMed
    1. Avedissian M., Lessing D., Gober J. W., Shapiro L., Gomes S. L. (1995). Regulation of the Caulobacter crescentus dnaKJ operon. J. Bacteriol. 177 3479–3484. 10.1128/JB.177.12.3479-3484.1995 - DOI - PMC - PubMed