Analysis of the regulation, expression, and localisation of the isocitrate lyase from Aspergillus fumigatus, a potential target for antifungal drug development

Ebel, Frank; Schwienbacher, Monika; Beyer, J.; Heesemann, Jürgen; Brakhage, Axel A.; Brock, Matthias

doi:10.1016/j.fgb.2006.01.015

Cited by 69 publications

(82 citation statements)

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“…In case of the wild-type and the complemented strain, therefore, the activity cannot be attributed solely to a single enzyme. Nevertheless, the increased citrate synthase activity on olive oil, when compared with glucose, is most likely due to the glyoxylate cycle, which is active on the former but not on the latter carbon source (Ebel et al, 2006;Schöbel et al, 2007).…”

Section: Analysis Of Methylcitrate Synthase and Citrate Synthase Actimentioning

confidence: 97%

Methylcitrate synthase from Aspergillus fumigatus is essential for manifestation of invasive aspergillosis

et al. 2007

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SummaryInvasive aspergillosis is a life-threatening disease mainly caused by the fungus Aspergillus fumigatus. In immunocompromised individuals conidia are not efficiently inactivated, which can end in invasive fungal growth. However, the metabolic requirements of the fungus are hardly known. Earlier investigations revealed an accumulation of toxic propionyl-CoA in a methylcitrate synthase mutant, when grown on propionyl-CoA-generating carbon sources. During invasive growth propionyl-CoA could derive from proteins, which are released from infected host tissues. We therefore assumed that a methylcitrate synthase mutant might display an attenuated virulence. Here we show that the addition of propionate to cell culture medium enhanced the ability of alveolar macrophages to kill methylcitrate synthase mutant but not wild-type conidia. When tested in a murine infection model, the methylcitrate synthase mutant displayed attenuated virulence and, furthermore, was cleared from tissues when mice survived the first phase of acute infection. The amplification of cDNA from infected mouse lungs confirmed the transcription of the methylcitrate synthase gene during invasion, which leads to the suggestion that amino acids indeed serve as growth-supporting nutrients during invasive growth of A. fumigatus. Thus, blocking of methylcitrate synthase activity abrogates fungal growth and provides a suitable target for new antifungals.

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Section: Analysis Of Methylcitrate Synthase and Citrate Synthase Actimentioning

confidence: 97%

Methylcitrate synthase from Aspergillus fumigatus is essential for manifestation of invasive aspergillosis

et al. 2007

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“…This is similar to the situation in Cryptococcus neoformans, where patterns of gene expression and adaptation were tissue specific for lung infection in mice (Hu et al, 2008) or in a rabbit model of experimental meningitis (Lee et al, 2010). Several studies have focused on the pathways of gluconeogenesis, the glyoxylate cycle and b-oxidation of fatty acids, as these pathways are specifically upregulated during contact with host immune cells in a variety of human fungal and bacterial pathogens, such as P. brasiliensis (Derengowski et al, 2008), Cryptococcus neoformans (Fan et al, 2005;Hu et al, 2008;Rude et al, 2002), Candida albicans (Barelle et al, 2006;Fradin et al, 2005;Ramírez & Lorenz, 2009), Aspergillus fumigatus (Ebel et al, 2006;Olivas et al, 2008) and Mycobacterium tuberculosis (McKinney et al, 2000;Muñoz-Elías & McKinney, 2005).…”

Section: R Peres Da Silva and Othersmentioning

confidence: 99%

Differential gene expression analysis of Paracoccidioides brasiliensis during keratinocyte infection

Silva

Matsumoto

Braz

et al. 2011

Journal of Medical Microbiology

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Paracoccidioides brasiliensis is the agent of paracoccidioidomycosis, one of the most important systemic fungal diseases in Latin America. This initiates in lung tissue and can subsequently disseminate to other tissues. Clinical manifestations range from localized forms to disseminated disease that can progress to lethality, probably depending on the relationships among the virulence of the fungus, the immune response and the ability to interact with the surface structures and invade epithelial cells and mononuclear cells of the host. It is generally regarded as a multifocal disease, with oral lesions as the prominent feature. The aim of this study was to evaluate P. brasiliensis yeast infection in normal oral keratinocytes (NOKs). The differential expression of mRNAs and proteins was also determined when the fungus was placed in contact with the cell in order to characterize differentially expressed genes and proteins during P. brasiliensis infection. After contact with NOKs, the fungus appeared to induce alterations in the cells, which showed cellular extensions and cavitations, probably resulting from changes in the actin cytoskeleton seen at 5 and 8 h after infection. Levels of protein expression were higher after reisolation of the fungus from infected NOK culture compared with culture of the fungus in medium. The analysis identified transcripts related to 19 proteins involved in different biological processes. Transcripts were found with multiple functions including induction of cytokines, protein metabolism, alternative carbon metabolism, zinc transport and the stress response during contact with NOKs. The proteins found suggested that the yeast was in a stress situation, as indicated by the presence of RDS1. Nevertheless, the yeast seemed to be proliferating and metabolically active, as shown by the presence of a proteasome, short-chain acetylator, glucosamine-6-phosphate isomerase and ADP/ATP carrier transcripts. Additionally, metabolic pathways may have been activated in order to eliminate toxic substances from the cell as a zinc transporter was detected, which is a potential target for the development of future drugs. INTRODUCTIONParacoccidioides brasiliensis is a thermodimorphic pathogenic fungus, the aetiological agent of paracoccidioidomycosis (PCM), an endemic disease geographically limited to Latin America and one of the most prevalent human deep systemic mycoses found in Brazil, Colombia and Venezuela (San-Blas et al., 2002). The transition from mycelium at 25 u C to yeast at 37 u C is essential for P. brasiliensis to establish the disease (Franco et al., 1997). P. brasiliensis may be inhaled and, once in the lungs, the fungus initiates a process of morphological transition into the pathogenic yeast form (San-Blas et al., 2002).PCM has a multiplicity of clinical presentations, from cutaneous to systemic forms, and can attack various tissues, especially the lungs (Benard & Franco, 2007). Oral mucosal lesions are commonly multiple, with a granular, mulberry-like surface and microulcerations, and ...

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“…Additionally, the use of 3-nitropropionate, a specific inhibitor of the isocitrate lyase, inhibited germination of conidia on media containing acetate as the sole carbon source, which confirms the essential role of isocitrate lyase to support growth on C 2 -generating carbon sources. We therefore concluded that an A. fumigatus mutant carrying a deletion of the isocitrate lyase coding region would also display attenuation in virulence in cases in which lipids or fatty acids provide a major carbon source during invasive aspergillosis (9).…”

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confidence: 95%

“…In a recent study, we investigated the isocitrate lyase from A. fumigatus in order to study the presence of the enzyme under various growth conditions (9). It was shown that isocitrate lyase is already present in conidia but is rapidly lost when the fungus grows on media which do not require the glyoxylate cycle for anaplerotic synthesis of oxaloacetate.…”

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confidence: 99%

Aspergillus fumigatusDoes Not Require Fatty Acid Metabolism via Isocitrate Lyase for Development of Invasive Aspergillosis

et al. 2007

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Aspergillus fumigatus is the most prevalent airborne filamentous fungus causing invasive aspergillosis in immunocompromised individuals. Only a limited number of determinants directly associated with virulence are known, and the metabolic requirements of the fungus to grow inside a host have not yet been investigated. Previous studies on pathogenic microorganisms, i.e., the bacterium Mycobacterium tuberculosis and the yeast Candida albicans, have revealed an essential role for isocitrate lyase in pathogenicity. In this study, we generated an isocitrate lyase deletion strain to test whether this strain shows attenuation in virulence. Results have revealed that isocitrate lyase from A. fumigatus is not required for the development of invasive aspergillosis. In a murine model of invasive aspergillosis, the wild-type strain, an isocitrate lyase deletion strain, and a complemented mutant strain were similarly effective in killing mice. Moreover, thin sections demonstrated invasive growth of all strains. Additionally, thin sections of lung tissue from patients with invasive aspergillosis stained with anti-isocitrate lyase antibodies remained negative. From these results, we cannot exclude the use of lipids or fatty acids as a carbon source for A. fumigatus during invasive growth. Nevertheless, test results do imply that the glyoxylate cycle from A. fumigatus is not required for the anaplerotic synthesis of oxaloacetate under infectious conditions. Therefore, an antifungal drug inhibiting fungal isocitrate lyases, postulated to act against Candida infections, is assumed to be ineffective against A. fumigatus.

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Analysis of the regulation, expression, and localisation of the isocitrate lyase from Aspergillus fumigatus, a potential target for antifungal drug development

Cited by 69 publications

References 50 publications

Methylcitrate synthase from Aspergillus fumigatus is essential for manifestation of invasive aspergillosis

Methylcitrate synthase from Aspergillus fumigatus is essential for manifestation of invasive aspergillosis

Differential gene expression analysis of Paracoccidioides brasiliensis during keratinocyte infection

Aspergillus fumigatusDoes Not Require Fatty Acid Metabolism via Isocitrate Lyase for Development of Invasive Aspergillosis

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