Thiol-based redox switches evolved as efficient post-translational regulatory mechanisms that enable individual proteins to rapidly respond to sudden environmental changes. While some protein functions need to be switched off to save resources and avoid potentially error-prone processes, protective functions become essential and need to be switched on. In this review, we focus on thiol-based activation mechanisms of stress-sensing chaperones. Upon stress exposure, these chaperones convert into high affinity binding platforms for unfolding proteins and protect cells against the accumulation of potentially toxic protein aggregates. Their chaperone activity is independent of ATP, a feature that becomes especially important under oxidative stress conditions, where cellular ATP levels drop and canonical ATP-dependent chaperones no longer operate. , reductive inactivation and substrate release require the restoration of ATP levels, which ensures refolding of client proteins by ATP-dependent foldases. We will give an overview over the different strategies that cells evolved to rapidly increase the pool of ATP-independent chaperones upon oxidative stress and provide mechanistic insights into how stress conditions are used to convert abundant cellular proteins into ATP-independent holding chaperones.
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http://dx.doi.org/10.1515/hsz-2020-0262 | DOI Listing |
Methods Mol Biol
December 2024
Raman Research Institute, Bangalore, Karnataka, India.
Biological cells sample their surrounding microenvironments using nanoscale force sensors on the cell surfaces. These surface-based force and stress sensors generate physical and chemical responses inside the cell. The inherently well-connected cytoskeleton and its physical contacts with the force elements on the nuclear membrane lead these physicochemical responses to cascade all the way inside the cell nucleus, physically altering the nuclear state.
View Article and Find Full Text PDFPlant Commun
December 2024
Center for Plant Biology, School of Life Sciences, Tsinghua University; Beijing, 100084, China. Electronic address:
In response to environmental stressors, plants have developed intricate mechanisms for rapid and efficient stress perception and adaptation. Recent research highlights the emerging role of biomolecular condensates in modulating plant stress sensing and response. These condensates function via numerous mechanisms to regulate cellular processes such as transcription, translation, RNA metabolism, and signaling pathways under stress conditions.
View Article and Find Full Text PDFJ Bacteriol
December 2024
Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
Unlabelled: The outer membrane (OM) of Gram-negative bacteria is the outermost layer of the cell and serves as permeability barrier against environmental toxins, including antibiotics. The OM is built by several pathways that transport and assemble lipids and proteins into the OM. Since the OM is an essential organelle for the cell, envelope stress responses (ESRs) continuously monitor its assembly to preserve viability if defects arise.
View Article and Find Full Text PDFmBio
November 2024
Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France.
Homologous recombination (HR) is a universally conserved mechanism of DNA strand exchange between homologous sequences, driven in bacteria by the RecA recombinase. HR is key for the maintenance of bacterial genomes via replication fork restart and DNA repair, as well as for their plasticity via the widespread mechanism of natural transformation. Transformation involves the capture and internalization of exogenous DNA in the form of single strands, followed by HR-mediated chromosomal integration.
View Article and Find Full Text PDFSoft Matter
November 2024
School of Materials Engineering, Purdue University, West Lafayette, IN, 47906, USA.
Localized stress concentrations at fiber ends in short fiber-reinforced polymer composites (SFRCs) significantly affect their mechanical properties. Our research targets these stress concentrations by embedding nitro-spiropyran (SPN) mechanophores into the polymer matrix. SPN mechanophores change color under mechanical stress, allowing us to visualize and quantify stress distributions at the fiber ends.
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