scholarly journals Rapid deacetylation of yeast Hsp70 mediates the cellular response to heat stress

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Linan Xu ◽  
Nitika ◽  
Naushaba Hasin ◽  
Daragh D. Cuskelly ◽  
Donald Wolfgeher ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Cellular Response ◽  
Transcriptional Response ◽  
Interaction Network ◽  
Post Translational Modifications ◽  
Translational Machinery ◽  
Chaperone Function ◽  
Lysine Residues ◽  
Client Proteins

Abstract Hsp70 is a highly conserved molecular chaperone critical for the folding of new and denatured proteins. While traditional models state that cells respond to stress by upregulating inducible HSPs, this response is relatively slow and is limited by transcriptional and translational machinery. Recent studies have identified a number of post-translational modifications (PTMs) on Hsp70 that act to fine-tune its function. We utilized mass spectrometry to determine whether yeast Hsp70 (Ssa1) is differentially modified upon heat shock. We uncovered four lysine residues on Ssa1, K86, K185, K354 and K562 that are deacetylated in response to heat shock. Mutation of these sites cause a substantial remodeling of the Hsp70 interaction network of co-chaperone partners and client proteins while preserving essential chaperone function. Acetylation/deacetylation at these residues alter expression of other heat-shock induced chaperones as well as directly influencing Hsf1 activity. Taken together our data suggest that cells may have the ability to respond to heat stress quickly though Hsp70 deacetylation, followed by a slower, more traditional transcriptional response.

scholarly journals Single-molecule fluorescence-based approach reveals novel mechanistic insights into human small heat shock protein chaperone function

2020 ◽  
pp. jbc.RA120.015419
Author(s):  
Caitlin L Johnston ◽  
Nicholas R Marzano ◽  
Bishnu P Paudel ◽  
George Wright ◽  
Justin L.P. Benesch ◽  
...  
Keyword(s):  
Heat Shock ◽  
Single Molecule ◽  
Small Heat Shock Protein ◽  
Vital Role ◽  
Misfolded Proteins ◽  
Single Molecule Fluorescence ◽  
Chaperone Function ◽  
Αb Crystallin ◽  
Client Proteins ◽  
Shock Proteins

Small heat shock proteins (sHsps) are a family of ubiquitous intracellular molecular chaperones that are up-regulated under stress conditions and play a vital role in protein homeostasis (proteostasis). It is commonly accepted that these chaperones work by trapping misfolded proteins to prevent their aggregation; however, fundamental questions regarding the molecular mechanism by which sHsps interact with misfolded proteins remain unanswered. The dynamic and polydisperse nature of sHsp oligomers has made studying them challenging using traditional biochemical approaches. Therefore, we have utilized a single-molecule fluorescence-based approach to observe the chaperone action of human αB-crystallin (αBc, HSPB5). Using this approach we have, for the first time, determined the stoichiometries of complexes formed between αBc and a model client protein, chloride intracellular channel 1 (CLIC1). By examining the dispersity and stoichiometries of these complexes over time, and in response to different concentrations of αBc, we have uncovered unique and important insights into a two-step mechanism by which αBc interacts with misfolded client proteins to prevent their aggregation.

scholarly journals Molecular Basis of the Defective Heat Stress Response in Mycobacterium leprae

2007 ◽  
Vol 189 (24) ◽  
pp. 8818-8827 ◽  
Author(s):  
Diana L. Williams ◽  
Tana L. Pittman ◽  
Mike Deshotel ◽  
Sandra Oby-Robinson ◽  
Issar Smith ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Response ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Elevated Temperatures ◽  
Transcriptional Response ◽  
Mycobacterium Leprae ◽  
Heat Stress Response ◽  
Regulatory Circuits ◽  
Shock Response

ABSTRACT Mycobacterium leprae, a major human pathogen, grows poorly at 37°C. The basis for its inability to survive at elevated temperatures was investigated. We determined that M. leprae lacks a protective heat shock response as a result of the lack of transcriptional induction of the alternative sigma factor genes sigE and sigB and the major heat shock operons, HSP70 and HSP60, even though heat shock promoters and regulatory circuits for these genes appear to be intact. M. leprae sigE was found to be capable of complementing the defective heat shock response of mycobacterial sigE knockout mutants only in the presence of a functional mycobacterial sigH, which orchestrates the mycobacterial heat shock response. Since the sigH of M. leprae is a pseudogene, these data support the conclusion that a key aspect of the defective heat shock response in M. leprae is the absence of a functional sigH. In addition, 68% of the genes induced during heat shock in M. tuberculosis were shown to be either absent from the M. leprae genome or were present as pseudogenes. Among these is the hsp/acr2 gene, whose product is essential for M. tuberculosis survival during heat shock. Taken together, these results suggest that the reduced ability of M. leprae to survive at elevated temperatures results from the lack of a functional transcriptional response to heat shock and the absence of a full repertoire of heat stress response genes, including sigH.

scholarly journals Exploring Novel Functions of the Small GTPase Ypt1p under Heat-Shock by Characterizing a Temperature-Sensitive Mutant Yeast Strain, ypt1-G80D

2019 ◽  
Vol 20 (1) ◽  
pp. 132 ◽  
Author(s):  
Chang Ho Kang ◽  
Joung Hun Park ◽  
Eun Seon Lee ◽  
Seol Ki Paeng ◽  
Ho Byoung Chae ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Molecular Chaperone ◽  
Stress Sensitivity ◽  
Small Gtpase ◽  
Stress Conditions ◽  
Temperature Sensitive ◽  
Heat Sensitivity ◽  
Chemical Chaperone ◽  
Chaperone Function

In our previous study, we found that Ypt1p, a Rab family small GTPase protein, exhibits a stress-driven structural and functional switch from a GTPase to a molecular chaperone, and mediates thermo tolerance in Saccharomyces cerevisiae. In the current study, we focused on the temperature-sensitive ypt1-G80D mutant, and found that the mutant cells are highly sensitive to heat-shock, due to a deficiency in the chaperone function of Ypt1pG80D. This defect results from an inability of the protein to form high molecular weight polymers, even though it retains almost normal GTPase function. The heat-stress sensitivity of ypt1-G80D cells was partially recovered by treatment with 4-phenylbutyric acid, a chemical chaperone. These findings indicate that loss of the chaperone function of Ypt1pG80D underlies the heat sensitivity of ypt1-G80D cells. We also compared the proteomes of YPT1 (wild-type) and ypt1-G80D cells to investigate Ypt1p-controlled proteins under heat-stress conditions. Our findings suggest that Ypt1p controls an abundance of proteins involved in metabolism, protein synthesis, cellular energy generation, stress response, and DNA regulation. Finally, we suggest that Ypt1p essentially regulates fundamental cellular processes under heat-stress conditions by acting as a molecular chaperone.

scholarly journals A novel multifunctional role for Hsp70 in binding post-translational modifications on clients

2021 ◽  
Author(s):  
Nitika ◽  
Bo Zheng ◽  
Linhao Ruan ◽  
Jake Kline ◽  
Jacek Sikora ◽  
...  
Keyword(s):  
Protein Function ◽  
Point Interaction ◽  
Post Translational Modifications ◽  
Definitive Evidence ◽  
Chaperone Function ◽  
Transient Nature ◽  
Hsp70 Protein ◽  
Response To Stress ◽  
Client Proteins ◽  
Self Association

Hsp70 interactions are critical for cellular viability and the response to stress. Previous attempts to characterize Hsp70 interactions have been limited by their transient nature and inability of current technologies to distinguish direct vs bridged interactions. We report the novel use of cross-linking mass spectrometry (XL-MS) to comprehensively characterize the budding yeast Hsp70 protein interactome. Using this approach, we have gained fundamental new insights into Hsp70 function, including definitive evidence of Hsp70 self-association as well as multi-point interaction with its client proteins. In addition to identifying a novel set of direct Hsp70 interactors which can be used to probe chaperone function in cells, we have also identified a suite of PTM-associated Hsp70 interactions. The majority of these PTMs have not been previously reported and appear to be critical in the regulation of client protein function. These data indicate that one of the mechanisms by which PTMs contribute to protein function is by facilitating interaction with chaperones. Taken together, we propose that XL-MS analysis of chaperone complexes may be used as a unique way to identify biologically-important PTMs on client proteins.

scholarly journals Caenorhabditis elegans AF4/FMR2 Family Homolog affl-2 Regulates Heat-Shock-Induced Gene Expression

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 1039-1054
Author(s):  
Sophie J. Walton ◽  
Han Wang ◽  
Porfirio Quintero-Cadena ◽  
Alex Bateman ◽  
Paul W. Sternberg
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Caenorhabditis Elegans ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Genetic Locus ◽  
Transcriptional Response ◽  
Transcriptional Elongation ◽  
Link Type ◽  
Shock Response

To mitigate the deleterious effects of temperature increases on cellular organization and proteotoxicity, organisms have developed mechanisms to respond to heat stress. In eukaryotes, HSF1 is the master regulator of the heat shock transcriptional response, but the heat shock response pathway is not yet fully understood. From a forward genetic screen for suppressors of heat-shock-induced gene expression in Caenorhabditis elegans, we found a new allele of hsf-1 that alters its DNA-binding domain, and we found three additional alleles of sup-45, a previously molecularly uncharacterized genetic locus. We identified sup-45 as one of the two hitherto unknown C. elegans orthologs of the human AF4/FMR2 family proteins, which are involved in regulation of transcriptional elongation rate. We thus renamed sup-45 as affl-2 (AF4/FMR2-Like). Through RNA-seq, we demonstrated that affl-2 mutants are deficient in heat-shock-induced transcription. Additionally, affl-2 mutants have herniated intestines, while worms lacking its sole paralog (affl-1) appear wild type. AFFL-2 is a broadly expressed nuclear protein, and nuclear localization of AFFL-2 is necessary for its role in heat shock response. affl-2 and its paralog are not essential for proper HSF-1 expression and localization after heat shock, which suggests that affl-2 may function downstream of, or parallel to, hsf-1. Our characterization of affl-2 provides insights into the regulation of heat-shock-induced gene expression to protect against heat stress.

scholarly journals A Novel Mechanism for Cross-Adaptation between Heat and Altitude Acclimation: The Role of Heat Shock Protein 90

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Roy M. Salgado ◽  
Ailish C. White ◽  
Suzanne M. Schneider ◽  
Christine M. Mermier
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 90 ◽  
Heat Acclimation ◽  
Functional Roles ◽  
Hypoxic Environment ◽  
Client Proteins

Heat shock protein 90 (HSP90) is a member of a family of molecular chaperone proteins which can be upregulated by various stressors including heat stress leading to increases in HSP90 protein expression. Its primary functions include (1) renaturing and denaturing of damaged proteins caused by heat stress and (2) interacting with client proteins to induce cell signaling for gene expression. The latter function is of interest because, in cancer cells, HSP90 has been reported to interact with the transcription hypoxic-inducible factor 1α (HIF1α). In a normoxic environment, HIF1α is degraded and therefore has limited physiological function. In contrast, in a hypoxic environment, stabilized HIF1α acts to promote erythropoiesis and angiogenesis. Since HSP90 interacts with HIF1α, and HSP90 can be upregulated from heat acclimation in humans, we present a proposal that heat acclimation can mimic molecular adaptations to those of altitude exposure. Specifically, we propose that heat acclimation increases HSP90 which then stabilizes HIF1α in a normoxic environment. This has many implications since HIF1α regulates red blood cell and vasculature formation. In this paper we will discuss (1) the functional roles of HSP90 and HIF1α, (2) the interaction between HSP90 and other client proteins including HIF1α, and (3) results from in vitro studies that may suggest how the relationship between HSP90 and HIF1α might be applied to individuals preparing to make altitude sojourns.

scholarly journals Caenorhabditis elegans AF4/FMR2 family homolog affl-2 is required for heat shock induced gene expression

2019 ◽  
Author(s):  
Sophie J. Walton ◽  
Han Wang ◽  
Porfirio Quintero-Cadena ◽  
Alex Bateman ◽  
Paul W. Sternberg
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Genetic Locus ◽  
Transcriptional Response ◽  
Egg Laying ◽  
Transcriptional Elongation ◽  
C Elegans ◽  
Shock Response

AbstractTo mitigate the deleterious effects of temperature increases on cellular organization and proteotoxicity, organisms have developed mechanisms to respond to heat stress. In eukaryotes, HSF1 is the master regulator of the heat shock transcriptional response, but the heat shock response pathway is not yet fully understood. From a forward genetic screen for suppressors of heat shock induced gene expression in C. elegans, we identified a new allele of hsf-1 that alters its DNA-binding domain, and three additional alleles of sup-45, a previously uncharacterized genetic locus. We identified sup-45 as one of the two hitherto unknown C. elegans orthologs of the human AF4/FMR2 family proteins, which are involved in regulation of transcriptional elongation rate. We thus renamed sup-45 as affl-2 (AF4/FMR2-Like). affl-2 mutants are egg-laying defective and dumpy, but worms lacking its sole paralog (affl-1) appear wild-type. AFFL-2 is a broadly expressed nuclear protein, and nuclear localization of AFFL-2 is necessary for its role in heat shock response. affl-2 and its paralog are not essential for proper HSF-1 expression and localization after heat shock, which suggests that affl-2 may function downstream or parallel of hsf-1. Our characterization of affl-2 provides insights into the complex processes of transcriptional elongation and regulating heat shock induced gene expression to protect against heat stress.

scholarly journals Insights Into Heat Response Mechanisms in Clematis Species: Physiological Analysis, Expression Profiles and Function Verification

2021 ◽  
Author(s):  
Hao Zhang ◽  
Changhua Jiang ◽  
Rui Wang ◽  
Long Zhang ◽  
Ruonan Gai ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Expression Profiles ◽  
Interaction Network ◽  
Differentially Expressed ◽  
Genes Encoding ◽  
Heat Response ◽  
Physiological Analysis ◽  
Japanese Gardens ◽  
Shock Proteins

Abstract Clematis species are commonly grown in western and Japanese gardens. Heat stress can inhibit many physiological processes mediating plant growth and development. The mechanism regulating responses to heat has been well characterized in Arabidopsis thaliana and some crops, but not in horticultural plants, including Clematis species. In this study, we found that Clematis alpina ‘Stolwijk Gold’ was heat-sensitive whereas Clematis vitalba and Clematis viticella ‘Polish Spirit’ were heat-tolerant based on the physiological analyses in heat stress. Transcriptomic profiling identified a set of heat tolerance-related genes (HTGs). Consistent with the observed phenotype in heat stress, 41.43% of the differentially expressed HTGs between heat treatment and control were down-regulated in heat-sensitive cultivar Stolwijk Gold, but only 9.80% and 20.79% of the differentially expressed HTGs in heat resistant C. vitalba and Polish Spirit, respectively. Co-expression network, protein–protein interaction network and phylogenetic analysis revealed that the genes encoding heat shock transcription factors (HSFs) and heat shock proteins (HSPs) played an essential role in Clematis resistance to heat stress. Ultimately, we proposed that two clades of HSFs may have diverse functions in regulating heat resistance from C. vitalba and CvHSFA2-2 could endow different host with high temperature resistance. This study provides first insights into the diversity of the heat response mechanisms among Clematis species.

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