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Related Concept Videos

Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

17.9K
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
17.9K
Regulation of the Unfolded Protein Response01:31

Regulation of the Unfolded Protein Response

2.4K
Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
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Protein Transport to the Outer Chloroplast Membrane01:11

Protein Transport to the Outer Chloroplast Membrane

2.0K
Chloroplast outer membrane proteins encoded by the nucleus are synthesized in the cytosol. Soon after synthesis, they bind cytosolic factors such as 14-3-3 protein and the Hsp70 chaperones that keep these precursors in an unfolded state until their translocation.
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
2.0K
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

3.6K
After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
3.6K
The Unfolded Protein Response01:37

The Unfolded Protein Response

4.5K
The ER is the hub of protein synthesis in a cell. It has robust systems to quality control protein folding and also for degradation of terminally misfolded proteins. Under normal conditions, a small proportion of misfolded proteins that cannot be salvaged need to be transported to the cytoplasm by the ER-associated degradation or ERAD pathways. However, if the ERAD cannot handle the misfolded proteins, the cell activates the unfolded protein response or UPR to adjust the protein folding...
4.5K
Protein Folding Quality Check in the RER01:29

Protein Folding Quality Check in the RER

3.7K
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
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Related Experiment Video

Updated: Jun 21, 2025

Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo
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Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo

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Periplasmic Chaperones: Outer Membrane Biogenesis and Envelope Stress.

Ashton N Combs1, Thomas J Silhavy1

  • 1Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA;

Annual Review of Microbiology
|July 15, 2024
PubMed
Summary
This summary is machine-generated.

Gram-negative bacteria rely on periplasmic chaperones for outer membrane biogenesis and envelope homeostasis. These ATP-independent chaperones possess sophisticated regulatory mechanisms to manage cellular stress and ensure survival.

Keywords:
envelope stress responsesgram-negative cell envelopeouter membrane protein biogenesisperiplasmperiplasmic chaperonesperiplasmic proteases

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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification
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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells

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Last Updated: Jun 21, 2025

Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo
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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification
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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells

Published on: September 2, 2019

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Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • Gram-negative bacteria possess a complex cell envelope essential for survival.
  • Periplasmic chaperones are crucial for outer membrane biogenesis and maintaining envelope homeostasis.
  • These chaperones function without external energy (ATP) and have evolved intricate regulatory mechanisms.

Purpose of the Study:

  • To provide an overview of key periplasmic chaperones in *Escherichia coli* involved in outer membrane biogenesis.
  • To discuss cellular stress responses that combat unfolded protein stress in the cell envelope.
  • To highlight the roles of periplasmic chaperones in restoring envelope homeostasis.

Main Methods:

  • Literature review of periplasmic chaperones in *Escherichia coli*.
  • Analysis of regulatory mechanisms for ATP-independent chaperone activity.
  • Examination of unfolded protein response pathways within the bacterial cell envelope.

Main Results:

  • Identified predominant periplasmic chaperones essential for outer membrane biogenesis in *E. coli*.
  • Detailed the sophisticated, ATP-independent regulatory mechanisms employed by these chaperones.
  • Characterized stress responses and the involvement of specific chaperones in restoring envelope homeostasis.

Conclusions:

  • Periplasmic chaperones are vital for gram-negative bacterial envelope integrity and survival.
  • Understanding chaperone regulation and stress response is key to bacterial cell envelope homeostasis.
  • This review consolidates knowledge on *E. coli* periplasmic chaperones and their role in cellular defense.