Mitochondrial activity and heat-shock response during morphogenesis in the pathogenic fungus Histoplasma capsulatum

1992 ◽  
Vol 70 (3-4) ◽  
pp. 207-214 ◽  
Author(s):  
Eduardo J. Patriarca ◽  
George S. Kobayashi ◽  
Bruno Maresca
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Elevated Temperatures ◽  
Histoplasma Capsulatum ◽  
Pathogenic Fungus ◽  
Temperature Shift ◽  
Mitochondrial Activity ◽  
Mitochondrial Atpase ◽  
Heat Shock Genes ◽  
Shock Response

Changes in temperature and a variety of other stimuli coordinately induce transcription of a specific set of heat-shock genes in all organisms. In the human fungal pathogen Histoplasma capsulatum, a temperature shift from 25 to 37 °C acts not only as a signal that causes transcription of heat-shock genes, but also triggers a morphological mycelium-to yeast-phase transition. The temperature-induced morphological transition may be viewed as a heat-shock response followed by cellular adaptation to a higher temperature. We have found that by inducing thermotolerance, i.e., an initial incubation at 34 °C, the thermosensitive attenuated Downs strain of H. capsulatum can be made to resemble those of the more temperature-tolerant G222B strain with respect to mitochondrial ATPase activity and electron transport efficiency at elevated temperatures. Furthermore, if the heat-shock response is first elicited by preincubation at milder temperatures or stress, transcription of heat-shock mRNA in mycelial cells of Downs strain that shifted to 37 °C proceeds at rates comparable to those of the virulent strains.Key words: heat shock, thermotolerance, ATPase, 70-kilodalton heat-shock protein, fungal morphogenesis.

Possible relationship of morphogenesis in pathogenic fungus, Histoplasma capsulatum, to heat shock response

Nature ◽  
1983 ◽  
Vol 303 (5920) ◽  
pp. 806-808 ◽  
Author(s):  
Alan M. Lambowitz ◽  
George S. Kobayashi ◽  
Audrey Painter ◽  
Gerald Medoff
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Histoplasma Capsulatum ◽  
Pathogenic Fungus ◽  
Shock Response ◽  
Relationship Of

scholarly journals Changes in Membrane Fluid State and Heat Shock Response Cause Attenuation of Virulence

2010 ◽  
Vol 192 (7) ◽  
pp. 1999-2005 ◽  
Author(s):  
Amalia Porta ◽  
Annamaria Eletto ◽  
Zsolt Török ◽  
Silvia Franceschelli ◽  
Attila Glatz ◽  
...  
Keyword(s):  
Heat Shock ◽  
Genetic Modification ◽  
Heat Shock Response ◽  
Mammalian Cells ◽  
Histoplasma Capsulatum ◽  
Genetic Manipulation ◽  
Microbial Pathogens ◽  
Fluid State ◽  
Shock Response ◽  
Serovar Typhimurium

ABSTRACT So far attenuation of pathogens has been mainly obtained by chemical or heat treatment of microbial pathogens. Recently, live attenuated strains have been produced by genetic modification. We have previously demonstrated that in several prokaryotes as well as in yeasts and mammalian cells the heat shock response is controlled by the membrane physical state (MPS). We have also shown that in Salmonella enterica serovar Typhimurium LT2 (Salmonella Typhimurium) overexpression of a Δ12-desaturase gene alters the MPS, inducing a sharp impairment of transcription of major heat shock genes and failure of the pathogen to grow inside macrophage (MΦ) (A. Porta et al., J. Bacteriol. 192:1988-1998, 2010). Here, we show that overexpression of a homologous Δ9-desaturase sequence in the highly virulent G217B strain of the human fungal pathogen Histoplasma capsulatum causes loss of its ability to survive and persist within murine MΦ along with the impairment of the heat shock response. When the attenuated strain of H. capsulatum was injected in a mouse model of infection, it did not cause disease. Further, treated mice were protected when challenged with the virulent fungal parental strain. Attenuation of virulence in MΦ of two evolutionarily distant pathogens was obtained by genetic modification of the MPS, suggesting that this is a new method that may be used to produce attenuation or loss of virulence in both other intracellular prokaryotic and eukaryotic pathogens. This new procedure to generate attenuated forms of pathogens may be used eventually to produce a novel class of vaccines based on the genetic manipulation of a pathogen's membrane fluid state and stress response.

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 Heat shock response of thermophilic fungi: membrane lipids and soluble carbohydrates under elevated temperatures

Microbiology ◽  
2016 ◽  
Vol 162 (6) ◽  
pp. 989-999 ◽  
Author(s):  
Elena A. Ianutsevich ◽  
Olga A. Danilova ◽  
Natalia V. Groza ◽  
Ekaterina R. Kotlova ◽  
Vera M. Tereshina
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Elevated Temperatures ◽  
Membrane Lipids ◽  
Soluble Carbohydrates ◽  
Thermophilic Fungi ◽  
Shock Response

Heat-shock response in Legionella pneumophila

1988 ◽  
Vol 34 (10) ◽  
pp. 1148-1153 ◽  
Author(s):  
Michael W. Lema ◽  
Arnold Brown ◽  
Charles A. Butler ◽  
Paul S. Hoffman
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Legionella Pneumophila ◽  
Heat Shock Response ◽  
Temperature Shift ◽  
Bacterial Cells ◽  
Groel Protein ◽  
Shock Response ◽  
Molecular Masses ◽  
Shock Proteins

The heat-shock response of Legionella pneumophila was examined by radiolabelling bacterial cell proteins with [35S]methionine following a temperature shift from 30 to 42 °C. Five heat-shock proteins were identified as having molecular masses of 17, 60, 70, 78, and 85 kilodaltons (kDa). The 85- and 60-kDa proteins were equally distributed between supernatant and pellet fractions following ultracentrifugation at 100 000 × g, the 70- and 78-kDa proteins were found primarily in the supernatant, and the 17-kDa protein was found primarily in the pellet. Synthesis of subsets of the heat-shock proteins could be stimulated by novobiocin, patulin, or puromycin. Ethanol, an effector of the heat-shock response in other microorganisms, had little effect on L. pneumophila, even at the highest concentration tolerated by the bacterial cells (1.9%). Finally, the 60-kDa heat-shock protein of L. pneumophila was immunologically cross-reactive with a polyclonal antibody prepared to the Escherichia coli groEL protein. However, a mouse monoclonal antibody reactive with the 60-kDa protein of all legionellae tested did not cross-react with the E. coli groEL protein, suggesting that the Legionella 60-kDa protein contains common and unique epitopes.

scholarly journals Cooperative Regulation of Campylobacter jejuni Heat-Shock Genes by HspR and HrcA

2020 ◽  
Vol 8 (8) ◽  
pp. 1161
Author(s):  
Marta Palombo ◽  
Vincenzo Scarlato ◽  
Davide Roncarati
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Campylobacter Jejuni ◽  
Heat Shock Response ◽  
Inverted Repeat ◽  
Regulatory Function ◽  
Heat Shock Genes ◽  
Repressive Effect ◽  
Shock Response ◽  
Regulated Promoters

The heat-shock response is defined by the transient gene-expression program that leads to the rapid accumulation of heat-shock proteins. This evolutionary conserved response aims at the preservation of the intracellular environment and represents a crucial pathway during the establishment of host–pathogen interaction. In the food-borne pathogen Campylobacter jejuni two transcriptional repressors, named HspR and HrcA, are involved in the regulation of the major heat-shock genes. However, the molecular mechanism underpinning HspR and HrcA regulatory function has not been defined yet. In the present work, we assayed and mapped the HspR and HrcA interactions on heat-shock promoters by high-resolution DNase I footprintings, defining their regulatory circuit, which governs C. jejuni heat-shock response. We found that, while DNA-binding of HrcA covers a compact region enclosing a single inverted repeat similar to the so-called Controlling Inverted Repeat of Chaperone Expression (CIRCE) sequence, HspR interacts with multiple high- and low-affinity binding sites, which contain HspR Associated Inverted Repeat (HAIR)-like sequences. We also explored the DNA-binding properties of the two repressors competitively on their common targets and observed, for the first time, that HrcA and HspR can directly interact and their binding on co-regulated promoters occurs in a cooperative manner. This mutual cooperative mechanism of DNA binding could explain the synergic repressive effect of HspR and HrcA observed in vivo on co-regulated promoters. Peculiarities of the molecular mechanisms exerted by HspR and HrcA in C. jejuni are compared to the closely related bacterium H. pylori that uses homologues of the two regulators.

scholarly journals The hrcA and hspR regulons of Campylobacter jejuni

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 158-166 ◽  
Author(s):  
Christopher W. Holmes ◽  
Charles W. Penn ◽  
Peter A. Lund
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Campylobacter Jejuni ◽  
Growth Temperature ◽  
Heat Shock Response ◽  
Human Pathogen ◽  
Response Regulators ◽  
Heat Shock Genes ◽  
Shock Response ◽  
Number Of Genes

The human pathogen Campylobacter jejuni has a classic heat shock response, showing induction of chaperones and proteases plus several unidentified proteins in response to a small increase in growth temperature. The genome contains two homologues to known heat shock response regulators, HrcA and HspR. Previous work has shown that HspR controls several heat-shock genes, but the hrcA regulon has not been defined. We have constructed single and double deletions of C. jejuni hrcA and hspR and analysed gene expression using microarrays. Only a small number of genes are controlled by these two regulators, and the two regulons overlap. Strains mutated in hspR, but not those mutated in hrcA, showed enhanced thermotolerance. Some genes previously identified as being downregulated in a strain lacking hspR showed no change in expression in our experiments.

scholarly journals Influence of temperature on the development, reproduction and regeneration in the flatworm model organism Macrostomum lignano

2018 ◽  
Author(s):  
Jakub Wudarski ◽  
Kirill Ustyantsev ◽  
Lisa Glazenburg ◽  
Eugene Berezikov
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Elevated Temperatures ◽  
Model Organism ◽  
Response Threshold ◽  
Reproduction Rate ◽  
Negative Consequences ◽  
Time Reproduction ◽  
Shock Response ◽  
Macrostomum Lignano

AbstractThe free-living marine flatworm Macrostomum lignano is a powerful model organism to study mechanisms of regeneration and stem cell regulation due to its convenient combination of biological and experimental properties, including the availability of transgenesis methods, which is unique among flatworm models. However, due to its relatively recent introduction in research, there are still many biological aspects of the animal that are not known. One of such questions is the influence of the culturing temperature on Macrostomum biology. Here we systematically investigated how different culturing temperatures affect the development time, reproduction rate, regeneration, heat shock response, and gene knockdown efficiency by RNA interference in M. lignano. We used marker transgenic lines of the flatworm to accurately measure the regeneration endpoint and to establish the stress response threshold for temperature shock. We found that compared to the culturing temperature of 20°C commonly used for M. lignano, elevated temperatures of 25°C-30°C substantially speed-up the development and regeneration time and increase reproduction rate without detectable negative consequences for the animal, while temperatures above 30°C elicit a heat shock response.We show that altering the temperature conditions can be used to shorten the time required to establish M. lignano cultures, store important lines and optimize the microinjection procedures for transgenesis. Our findings will help to optimize the design of experiments in M. lignano and thus facilitate future research in this model organism.

scholarly journals Regulatory Conservation and Divergence of ς32 Homologs from Gram-Negative Bacteria: Serratia marcescens, Proteus mirabilis, Pseudomonas aeruginosa, and Agrobacterium tumefaciens

1998 ◽  
Vol 180 (9) ◽  
pp. 2402-2408 ◽  
Author(s):  
Kenji Nakahigashi ◽  
Hideki Yanagi ◽  
Takashi Yura
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Heat Shock ◽  
Serratia Marcescens ◽  
Proteus Mirabilis ◽  
Heat Shock Response ◽  
Gram Negative Bacteria ◽  
Heat Shock Genes ◽  
Gram Negative ◽  
E Coli ◽  
Shock Response

ABSTRACT The heat shock response in Escherichia coli is mediated primarily by the rpoH gene, encoding ς32, which is specifically required for transcription of heat shock genes. A number of ς32 homologs have recently been cloned from gram-negative bacteria that belong to the gamma or alpha subdivisions of the proteobacteria. We report here some of the regulatory features of several such homologs (RpoH) expressed in E. coli as well as in respective cognate bacteria. When expressed in an E. coli ΔrpoH strain lacking its own ς32, these homologs activated the transcription of heat shock genes (groE and dnaK) from the start sites normally used in E. coli. The level of RpoH inSerratia marcescens and Pseudomonas aeruginosacells was very low at 30°C but was elevated markedly upon a shift to 42°C, as found previously with E. coli. The increased RpoH levels upon heat shock resulted from both increased synthesis and stabilization of the normally unstable RpoH protein. In contrast, the RpoH level in Proteus mirabilis was relatively high at 30°C and increased less markedly upon heat shock, mostly by increased synthesis; this ς32 homolog was already stable at 30°C, and little further stabilization occurred upon the shift to 42°C. The increased synthesis of RpoH homologs in all these gamma proteobacteria was observed even in the presence of rifampin, suggesting that the induction occurred at the level of translation. Thus, the basic regulatory strategy of the heat shock response by enhancing the RpoH level is well conserved in the gamma proteobacteria, but some divergence in the actual mechanisms used occurred during evolution.

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