Extracellular Proteins as Enterobacterial Thermometers

2003 ◽  
Vol 86 (1-2) ◽  
pp. 139-156 ◽  
Author(s):  
Robin J. Rowbury
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Stress Responses ◽  
Direct Evidence ◽  
Experimental Studies ◽  
Extracellular Proteins ◽  
Temperature Changes ◽  
Induction Components ◽  
Cellular Components ◽  
Thermal Stimuli

Biological thermometers are cellular components or structures which sense increasing temperatures, interaction of the thermometer and the thermal stress bringing about the switching-on of inducible responses, with gradually enhanced levels of response induction following gradually increasing temperatures. In enterobacteria, for studies of such thermometers, generally induction of heat shock protein (HSP) synthesis has been examined, with experimental studies aiming to establish (often indirectly) how the temperature changes which initiate HSP synthesis are sensed; numerous other processes and responses show graded induction as temperature is increased, and how the temperature changes which induce these are sensed is also of interest. Several classes of intracellular component and structure have been proposed as enterobacterial thermometers, with the ribosome and the DnaK chaperone being the most favoured, although for many of the proposed intracellular thermometers, most of the evidence for their functioning in this way is indirect. In contrast to the above, the studies reviewed here firmly establish that for four distinct stress responses, which are switched-on gradually as temperature increases, temperature changes are sensed by extracellular components (extracellular sensing components, ESCs) i.e. there is firm and direct evidence for the occurrence of extracellular thermometers. All four thermometers described here are proteins, which appear to be distinct and different from each other, and on sensing thermal stress are activated by it to four distinct extracellular induction components (EICs), which interact with receptors on the surface of organisms to induce the appropriate responses. It is predicted that many other temperature-induced processes, including the synthesis of HSPs, will be switched-on following the activation of similar extracellular thermometers by thermal stimuli.

scholarly journals Thermal stress responses of Sodalis glossinidius, an indigenous bacterial symbiont of hematophagous tsetse flies

2019 ◽  
Author(s):  
Jose Santinni Roma ◽  
Shaina D’Souza ◽  
Patrick J. Somers ◽  
Leah F. Cabo ◽  
Ruhan Farsin ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Stress Responses ◽  
Thermal Tolerance ◽  
Molecular Mechanisms ◽  
Symbiotic Bacteria ◽  
Tsetse Flies ◽  
African Trypanosomes ◽  
Sodalis Glossinidius ◽  
Insight Into

ABSTRACTTsetse flies (Diptera: Glossinidae) house a taxonomically diverse microbiota that includes environmentally acquired bacteria, maternally transmitted symbiotic bacteria, and pathogenic African trypanosomes. Sodalis glossinidius, which is a facultative symbiont that resides intra and extracellularly within multiple tsetse tissues, has been implicated as a mediator of trypanosome infection establishment in the fly’s gut. Tsetse’s gut-associated population of Sodalis are subjected to marked temperature fluctuations each time their ectothermic fly host imbibes vertebrate blood. The molecular mechanisms that Sodalis employs to deal with this heat stress are unknown. In this study, we examined the thermal tolerance and heat shock response of Sodalis. When grown on BHI agar plates, the bacterium exhibited the most prolific growth at 25°C, and did not grow at temperatures above 30°C. Growth on BHI agar plates at 31°C was dependent on either the addition of blood to the agar or reduction in oxygen levels. Sodalis was viable in liquid cultures for 24 hours at 30°C, but began to die upon further exposure. The rate of death increased with increased temperature. Similarly, Sodalis was able to survive for 48 hours within tsetse flies housed at 30°C, while a higher temperature (37°C) was lethal. Sodalis’ genome contains homologues of the heat shock chaperone protein-encoding genes dnaK, dnaJ, and grpE, and their expression was up-regulated in thermally stressed Sodalis, both in vitro and in vivo within tsetse flies. Arrested growth of E. coli dnaK, dnaJ, or grpE mutants under thermal stress was reversed when the cells were transformed with a low copy plasmid that encoded the Sodalis homologues of these genes. The information contained in this study provides insight into how arthropod vector enteric commensals, many of which mediate their host’s ability to transmit pathogens, mitigate heat shock associated with the ingestion of a blood meal.AUTHOR SUMMARYMicroorganisms associated with insects must cope with fluctuating temperatures. Because symbiotic bacteria influence the biology of their host, how they respond to temperature changes will have an impact on the host and other microorganisms in the host. The tsetse fly and its symbionts represent an important model system for studying thermal tolerance because the fly feeds exclusively on vertebrate blood and is thus exposed to dramatic temperature shifts. Tsetse flies house a microbial community that can consist of symbiotic and environmentally acquired bacteria, viruses, and parasitic African trypanosomes. This work, which makes use of tsetse’s commensal symbiont, Sodalis glossinidius, is significance because it represents the only examination of thermal tolerance mechanisms in a bacterium that resides indigenously within an arthropod disease vector. A better understanding of the biology of thermal tolerance in Sodalis provides insight into thermal stress survival in other insect symbionts and may yield information to help control vector-borne disease.

scholarly journals Arabidopsis heat shock transcription factor HSFA7b positively mediates salt stress tolerance by binding to an E-box-like motif to regulate gene expression

2019 ◽  
Vol 70 (19) ◽  
pp. 5355-5374 ◽  
Author(s):  
Dandan Zang ◽  
Jingxin Wang ◽  
Xin Zhang ◽  
Zhujun Liu ◽  
Yucheng Wang
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Heat Shock ◽  
Salt Tolerance ◽  
Stress Responses ◽  
Ion Homeostasis ◽  
Cellulose Synthase ◽  
Regulate Gene Expression ◽  
E Box ◽  
Regulate Gene

Abstract Plant heat shock transcription factors (HSFs) are involved in heat and other abiotic stress responses. However, their functions in salt tolerance are little known. In this study, we characterized the function of a HSF from Arabidopsis, AtHSFA7b, in salt tolerance. AtHSFA7b is a nuclear protein with transactivation activity. ChIP-seq combined with an RNA-seq assay indicated that AtHSFA7b preferentially binds to a novel cis-acting element, termed the E-box-like motif, to regulate gene expression; it also binds to the heat shock element motif. Under salt conditions, AtHSFA7b regulates its target genes to mediate serial physiological changes, including maintaining cellular ion homeostasis, reducing water loss rate, decreasing reactive oxygen species accumulation, and adjusting osmotic potential, which ultimately leads to improved salt tolerance. Additionally, most cellulose synthase-like (CSL) and cellulose synthase (CESA) family genes were inhibited by AtHSFA7b; some of them were randomly selected for salt tolerance characterization, and they were mainly found to negatively modulate salt tolerance. By contrast, some transcription factors (TFs) were induced by AtHSFA7b; among them, we randomly identified six TFs that positively regulate salt tolerance. Thus, AtHSFA7b serves as a transactivator that positively mediates salinity tolerance mainly through binding to the E-box-like motif to regulate gene expression.

scholarly journals Unravelling thermal stress due to thermal expansion mismatch in metal–organic frameworks for methane storage

2021 ◽  
Author(s):  
Jelle Wieme ◽  
Veronique Van Speybroeck
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Pressure Coefficient ◽  
Metal Organic Frameworks ◽  
Methane Storage ◽  
Thermal Expansion Mismatch ◽  
Thermal Pressure ◽  
Temperature Changes ◽  
Metal Organic ◽  
The Impact

Thermal stress is present in metal–organic frameworks undergoing temperature changes during adsorption and desorption. We computed the thermal pressure coefficient as a proxy for this phenomenon and discuss the impact of thermal expansion mismatch.

scholarly journals Heat shock factor 2 is required for maintaining proteostasis against febrile-range thermal stress and polyglutamine aggregation

2011 ◽  
Vol 22 (19) ◽  
pp. 3571-3583 ◽  
Author(s):  
Toyohide Shinkawa ◽  
Ke Tan ◽  
Mitsuaki Fujimoto ◽  
Naoki Hayashida ◽  
Kaoru Yamamoto ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Protein Misfolding ◽  
Reproductive Organs ◽  
Heat Shock Factors ◽  
Mild Heat ◽  
Promising Therapeutic Target ◽  
Αb Crystallin ◽  
Shock Proteins ◽  
Polyglutamine Protein

Heat shock response is characterized by the induction of heat shock proteins (HSPs), which facilitate protein folding, and non-HSP proteins with diverse functions, including protein degradation, and is regulated by heat shock factors (HSFs). HSF1 is a master regulator of HSP expression during heat shock in mammals, as is HSF3 in avians. HSF2 plays roles in development of the brain and reproductive organs. However, the fundamental roles of HSF2 in vertebrate cells have not been identified. Here we find that vertebrate HSF2 is activated during heat shock in the physiological range. HSF2 deficiency reduces threshold for chicken HSF3 or mouse HSF1 activation, resulting in increased HSP expression during mild heat shock. HSF2-null cells are more sensitive to sustained mild heat shock than wild-type cells, associated with the accumulation of ubiquitylated misfolded proteins. Furthermore, loss of HSF2 function increases the accumulation of aggregated polyglutamine protein and shortens the lifespan of R6/2 Huntington's disease mice, partly through αB-crystallin expression. These results identify HSF2 as a major regulator of proteostasis capacity against febrile-range thermal stress and suggest that HSF2 could be a promising therapeutic target for protein-misfolding diseases.

Development of the embryonic heat shock response and the impact of repeated thermal stress in early stage lake whitefish ( Coregonus clupeaformis ) embryos

2017 ◽  
Vol 69 ◽  
pp. 294-301 ◽  
Author(s):  
Lindy M. Whitehouse ◽  
Chance S. McDougall ◽  
Daniel I. Stefanovic ◽  
Douglas R. Boreham ◽  
Christopher M. Somers ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Early Stage ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Shock Response ◽  
The Impact

scholarly journals Testosterone relaxes coronary arteries by opening the large-conductance, calcium-activated potassium channel

2001 ◽  
Vol 281 (4) ◽  
pp. H1720-H1727 ◽  
Author(s):  
Viju P. Deenadayalu ◽  
Richard E. White ◽  
John N. Stallone ◽  
Xumei Gao ◽  
Alfredo J. Garcia
Keyword(s):  
Coronary Arteries ◽  
Direct Evidence ◽  
Experimental Studies ◽  
Acute Effects ◽  
Potassium Efflux ◽  
Porcine Coronary Artery ◽  
Male Health ◽  
Independent Mechanism ◽  
Calcium Activated Potassium Channel ◽  
Coronary Relaxation

Cardiovascular diseases are often considered to be a predominantly male health problem, and it has been suggested that testosterone exerts deleterious effects on cardiovascular function; however, few experimental studies support this suggestion. Moreover, the cellular and molecular mechanism(s) underlying vascular responses to testosterone is unknown. The present study has investigated the acute effects of testosterone on porcine coronary artery smooth muscle at the tissue and cellular levels. Contractile studies demonstrated that testosterone or dihydrotestosterone (a nonaromatizable metabolite) relaxed these arteries by an endothelium-independent mechanism involving potassium efflux. Direct evidence from patch-clamp studies confirmed that testosterone opened K+ channels in single coronary myocytes, and further analysis identified this protein as the large-conductance, calcium- and voltage-activated potassium (BKCa) channel. Moreover, inhibiting BKCachannel activity significantly attenuated testosterone-induced coronary relaxation. These findings indicate that testosterone relaxes porcine coronary arteries predominantly by opening BKCa channels in coronary myocytes, and this response may be associated with accumulation of cGMP. This novel mechanism may provide a better understanding of testosterone-induced vasorelaxation reported in recent experimental and early clinical studies.

scholarly journals Expression pattern of heat shock proteins during acute thermal stress in the Antarctic sea urchin, Sterechinus neumayeri

2016 ◽  
Vol 89 (1) ◽  
Author(s):  
Karina González ◽  
Juan Gaitán-Espitia ◽  
Alejandro Font ◽  
César A. Cárdenas ◽  
Marcelo González-Aravena
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Expression Pattern ◽  
Sea Urchin ◽  
Sterechinus Neumayeri ◽  
Shock Proteins ◽  
The Antarctic

scholarly journals Dynamic oligopeptide acquisition by the RagAB transporter from Porphyromonas gingivalis

2019 ◽  
Author(s):  
Mariusz Madej ◽  
Joshua B. R. White ◽  
Zuzanna Nowakowska ◽  
Shaun Rawson ◽  
Carsten Scavenius ◽  
...  
Keyword(s):  
Porphyromonas Gingivalis ◽  
Direct Evidence ◽  
Inflammatory Diseases ◽  
Extracellular Proteins ◽  
Substrate Selectivity ◽  
Binding Studies ◽  
Uptake Mechanism ◽  
X Ray ◽  
Cryo Electron Microscopy ◽  
Binding Surface

AbstractPorphyromonas gingivalis, an asaccharolytic Bacteroidetes, is a keystone pathogen in human periodontitis that may also contribute to the development of other chronic inflammatory diseases, such as rheumatoid arthritis, cardiovascular disease and Alzheimer’s disease. P. gingivalis utilizes protease-generated peptides derived from extracellular proteins for growth, but how those peptides enter the cell is not clear. Here we identify RagAB as the outer membrane importer for peptides. X-ray crystal structures show that the transporter forms a dimeric RagA2B2 complex with the RagB substrate binding surface-anchored lipoprotein forming a closed lid on the TonB-dependent transporter RagA. Cryo-electron microscopy structures reveal the opening of the RagB lid and thus provide direct evidence for a “pedal bin” nutrient uptake mechanism. Together with mutagenesis, peptide binding studies and RagAB peptidomics, our work identifies RagAB as a dynamic OM oligopeptide acquisition machine with considerable substrate selectivity that is essential for the efficient utilisation of proteinaceous nutrients by P. gingivalis.

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