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The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.


Deletion of HAT1 and HAT2 increases oxidative stress resistance and azole tolerance.(A) Cells lacking Hat1 or Hat2 show increased resistance to H2O2. Lack of both genes mimics the corresponding single deletion strains. (B) Deletion of HAT1 increases resistance to tert-butyl hydroperoxide (tBOOH). Lack of Rtt109 does not affect tBOOH sensitivity. (C) Loss of Hat1 causes reduced susceptibility to voriconazole (Voric.) and itraconazole (Itrac.). Deletion of HAT2 or HAT1 and HAT2 mimics loss of Hat1. (D) Deletion of RTT109 or RAD52 does not increase voriconazole tolerance. (A-D) Fivefold serial dilutions of the indicated strains were spotted on agar plates containing the indicated substances and pictures were taken after incubation at 30°C for 3 days.
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ppat.1005218.g001: Deletion of HAT1 and HAT2 increases oxidative stress resistance and azole tolerance.(A) Cells lacking Hat1 or Hat2 show increased resistance to H2O2. Lack of both genes mimics the corresponding single deletion strains. (B) Deletion of HAT1 increases resistance to tert-butyl hydroperoxide (tBOOH). Lack of Rtt109 does not affect tBOOH sensitivity. (C) Loss of Hat1 causes reduced susceptibility to voriconazole (Voric.) and itraconazole (Itrac.). Deletion of HAT2 or HAT1 and HAT2 mimics loss of Hat1. (D) Deletion of RTT109 or RAD52 does not increase voriconazole tolerance. (A-D) Fivefold serial dilutions of the indicated strains were spotted on agar plates containing the indicated substances and pictures were taken after incubation at 30°C for 3 days.

Mentions: In a previous study, we identified the C. albicans NuB4 complex being essential for efficient repair of both exogenous and endogenous DNA damage [10]. C. albicans DNA damage repair mutants show increased susceptibility to ROS produced by immune cells [30]. Therefore, we asked if inactivation of the NuB4 complex would render this pathogen hypersusceptible to H2O2. Surprisingly, however, deletion of HAT1, HAT2 or both genes increased the resistance to H2O2 as determined by spot dilution assays (Fig 1A). Importantly, reintegration of HAT1 or HAT2 at its endogenous locus fully restored the wild-type phenotype (Fig 1A).


The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Deletion of HAT1 and HAT2 increases oxidative stress resistance and azole tolerance.(A) Cells lacking Hat1 or Hat2 show increased resistance to H2O2. Lack of both genes mimics the corresponding single deletion strains. (B) Deletion of HAT1 increases resistance to tert-butyl hydroperoxide (tBOOH). Lack of Rtt109 does not affect tBOOH sensitivity. (C) Loss of Hat1 causes reduced susceptibility to voriconazole (Voric.) and itraconazole (Itrac.). Deletion of HAT2 or HAT1 and HAT2 mimics loss of Hat1. (D) Deletion of RTT109 or RAD52 does not increase voriconazole tolerance. (A-D) Fivefold serial dilutions of the indicated strains were spotted on agar plates containing the indicated substances and pictures were taken after incubation at 30°C for 3 days.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4608838&req=5

ppat.1005218.g001: Deletion of HAT1 and HAT2 increases oxidative stress resistance and azole tolerance.(A) Cells lacking Hat1 or Hat2 show increased resistance to H2O2. Lack of both genes mimics the corresponding single deletion strains. (B) Deletion of HAT1 increases resistance to tert-butyl hydroperoxide (tBOOH). Lack of Rtt109 does not affect tBOOH sensitivity. (C) Loss of Hat1 causes reduced susceptibility to voriconazole (Voric.) and itraconazole (Itrac.). Deletion of HAT2 or HAT1 and HAT2 mimics loss of Hat1. (D) Deletion of RTT109 or RAD52 does not increase voriconazole tolerance. (A-D) Fivefold serial dilutions of the indicated strains were spotted on agar plates containing the indicated substances and pictures were taken after incubation at 30°C for 3 days.
Mentions: In a previous study, we identified the C. albicans NuB4 complex being essential for efficient repair of both exogenous and endogenous DNA damage [10]. C. albicans DNA damage repair mutants show increased susceptibility to ROS produced by immune cells [30]. Therefore, we asked if inactivation of the NuB4 complex would render this pathogen hypersusceptible to H2O2. Surprisingly, however, deletion of HAT1, HAT2 or both genes increased the resistance to H2O2 as determined by spot dilution assays (Fig 1A). Importantly, reintegration of HAT1 or HAT2 at its endogenous locus fully restored the wild-type phenotype (Fig 1A).

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.