Characterization of the gene family encoding alternative oxidase from Candida albicans

2001 ◽  
Vol 356 (2) ◽  
pp. 595-604 ◽  
Author(s):  
Won-Ki HUH ◽  
Sa-Ouk KANG
Keyword(s):  
Candida Albicans ◽  
Gene Family ◽  
Alternative Oxidase ◽  
Carbon Sources ◽  
Cloning And Expression ◽  
Respiratory Pathway ◽  
Reading Frame ◽  
Genes Encoding ◽  
Reporter Assays ◽  
Cyanide Resistant Respiration

Candida albicans possesses a cyanide-resistant respiratory pathway mediated by alternative oxidase (AOX), which seems to be encoded by a gene family with two members. Cloning and expression of AOX1a, one of the genes encoding alternative oxidase from C. albicans, has previously been reported [Huh and Kang (1999) J. Bacteriol. 181, 4098–4102]. In the present study we report the isolation of another gene coding for alternative oxidase, designated AOX1b. AOX1b contains a continuous open reading frame that encodes a polypeptide consisting of 365 amino acids. Interestingly, AOX1a and AOX1b were found to be located in tandem on one of the chromosomes of C. albicans. The presence of cyanide in the culture medium remarkably retarded the growth of the aox1a/aox1a mutants. The growth of the aox1b/aox1b mutants and the aox1a/aox1a aox1b/aox1b double mutants was almost completely inhibited in the same medium. β-Galactosidase reporter assays indicated that, whereas AOX1a was expressed constitutively, the expression of AOX1b was dependent on growth phase and was induced by treatment with cyanide, antimycin A, H2O2, menadione and paraquat. Growth of the cells in media with non-fermentable carbon sources also enhanced the expression of AOX1b. CaSLN1, which encodes a histidine kinase, seems to be involved in the regulation of AOX expression in C. albicans on the basis of the observation that the activity of cyanide-resistant respiration and the expression level of AOX in the casln1/casln1 mutants were found to be significantly low under normal conditions and slightly increased in the presence of respiratory inhibitors compared with the wild-type strain. Like AOX1a, AOX1b could also be functionally expressed in AOX-deficient Saccharomyces cerevisiae and confer cyanide-resistant respiration on the organism.

scholarly journals Molecular Cloning and Functional Expression of Alternative Oxidase from Candida albicans

1999 ◽  
Vol 181 (13) ◽  
pp. 4098-4102 ◽  
Author(s):  
Won-Ki Huh ◽  
Sa-Ouk Kang
Keyword(s):  
Candida Albicans ◽  
Genomic Dna ◽  
Alternative Oxidase ◽  
Respiratory Activity ◽  
Functional Expression ◽  
Antimycin A ◽  
Calculated Molecular Mass ◽  
Dna Library ◽  
Genomic Dna Library ◽  
Cyanide Resistant Respiration

ABSTRACT The AOX1 gene, which encodes an alternative oxidase, was isolated from the genomic DNA library of Candida albicans. The gene encodes a polypeptide consisting of 379 amino acids with a calculated molecular mass of 43,975 Da. Theaox1/aox1 mutant strain did not show cyanide-resistant respiration under normal conditions but could still induce cyanide-resistant respiration when treated with antimycin A. The measurement of respiratory activity and Western blot analysis suggested the presence of another AOX. When C. albicans AOX1 was expressed in alternative oxidase-deficient Saccharomyces cerevisiae, it could confer cyanide-resistant respiration onS. cerevisiae.

scholarly journals Initiation of Protein Synthesis in Saccharomyces cerevisiae Mitochondria without Formylation of the Initiator tRNA

2000 ◽  
Vol 182 (10) ◽  
pp. 2886-2892 ◽  
Author(s):  
Yan Li ◽  
William B. Holmes ◽  
Dean R. Appling ◽  
Uttam L. RajBhandary
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Carbon Sources ◽  
Normal Growth ◽  
Direct Analysis ◽  
Deletion Strain ◽  
Reading Frame ◽  
Saccharomyces Cerevisiae Mitochondria ◽  
Genes Encoding

ABSTRACT Protein synthesis in eukaryotic organelles such as mitochondria and chloroplasts is widely believed to require a formylated initiator methionyl tRNA (fMet-tRNAfMet) for initiation. Here we show that initiation of protein synthesis in yeast mitochondria can occur without formylation of the initiator methionyl-tRNA (Met-tRNAfMet). The formylation reaction is catalyzed by methionyl-tRNA formyltransferase (MTF) located in mitochondria and usesN 10-formyltetrahydrofolate (10-formyl-THF) as the formyl donor. We have studied yeast mutants carrying chromosomal disruptions of the genes encoding the mitochondrial C1-tetrahydrofolate (C1-THF) synthase (MIS1), necessary for synthesis of 10-formyl-THF, and the methionyl-tRNA formyltransferase (open reading frame YBL013W; designated FMT1). A direct analysis of mitochondrial tRNAs using gel electrophoresis systems that can separate fMet-tRNAfMet, Met-tRNAfMet, and tRNAfMet shows that there is no formylation in vivo of the mitochondrial initiator Met-tRNA in these strains. In contrast, the initiator Met-tRNA is formylated in the respective “wild-type” parental strains. In spite of the absence of fMet-tRNAfMet, the mutant strains exhibited normal mitochondrial protein synthesis and function, as evidenced by normal growth on nonfermentable carbon sources in rich media and normal frequencies of generation ofpetite colonies. The only growth phenotype observed was a longer lag time during growth on nonfermentable carbon sources in minimal media for the mis1 deletion strain but not for thefmt1 deletion strain.

scholarly journals Immunolocalization of an Alternative Respiratory Chain in Antonospora (Paranosema) locustae Spores: Mitosomes Retain Their Role in Microsporidial Energy Metabolism

2011 ◽  
Vol 10 (4) ◽  
pp. 588-593 ◽  
Author(s):  
Viacheslav V. Dolgikh ◽  
Igor V. Senderskiy ◽  
Olga A. Pavlova ◽  
Anton M. Naumov ◽  
Galina V. Beznoussenko
Keyword(s):  
Energy Metabolism ◽  
Respiratory Chain ◽  
Alternative Oxidase ◽  
Krebs Cycle ◽  
Glycerol Phosphate ◽  
Respiratory Pathway ◽  
Content Type ◽  
Genes Encoding ◽  
Mitochondrial Hsp70 ◽  
Recombinant Polypeptides

ABSTRACT Microsporidia are a group of fungus-related intracellular parasites with severely reduced metabolic machinery. They lack canonical mitochondria, a Krebs cycle, and a respiratory chain but possess genes encoding glycolysis enzymes, a glycerol phosphate shuttle, and ATP/ADP carriers to import host ATP. The recent finding of alternative oxidase genes in two clades suggests that microsporidial mitosomes may retain an alternative respiratory pathway. We expressed the fragments of mitochondrial chaperone Hsp70 (mitHsp70), mitochondrial glycerol-3-phosphate dehydrogenase (mitG3PDH), and alternative oxidase (AOX) from the microsporidium Antonospora (Paranosema) locustae in Escherichia coli. Immunoblotting with antibodies against recombinant polypeptides demonstrated specific accumulation of both metabolic enzymes in A. locustae spores. At the same time comparable amounts of mitochondrial Hsp70 were found in spores and in stages of intracellular development as well. Immunoelectron microscopy of ultrathin cryosections of spores confirmed mitosomal localization of the studied proteins. Small amounts of enzymes of an alternative respiratory chain in merogonial and early sporogonial stages, alongside their accumulation in mature spores, suggest conspicuous changes in components and functions of mitosomes during the life cycle of microsporidia and the important role of these organelles in parasite energy metabolism, at least at the final stages of sporogenesis.

scholarly journals The Transcription Factor Homolog CTF1 Regulates β-Oxidation in Candida albicans

2009 ◽  
Vol 8 (10) ◽  
pp. 1604-1614 ◽  
Author(s):  
Melissa A. Ramírez ◽  
Michael C. Lorenz
Keyword(s):  
Candida Albicans ◽  
Carbon Metabolism ◽  
Regulatory Network ◽  
Glyoxylate Cycle ◽  
Carbon Sources ◽  
Microbial Pathogens ◽  
Peroxisomal Biogenesis ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
The Glyoxylate Cycle

ABSTRACT Carbon starvation is one of the many stresses to which microbial pathogens are subjected while in the host. Pathways necessary for the utilization of alternative carbon sources, such as gluconeogenesis, the glyoxylate cycle, and β-oxidation of fatty acids, have been shown to be required for full virulence in several systems, including the fungal pathogen Candida albicans. We have investigated the regulatory network governing alternative carbon metabolism in this organism through characterization of transcriptional regulators identified based on the model fungi, Saccharomyces cerevisiae and Aspergillus nidulans. C. albicans has homologs of the ScCAT8/AnFacB and ScADR1/AnAmdX transcription factors that regulate induction of genes encoding the proteins of gluconeogenesis, the glyoxylate cycle, and ethanol utilization. Surprisingly, C. albicans mutants lacking CAT8 or ADR1 have no apparent phenotypes and do not regulate genes for key enzymes of these pathways. Fatty acid degradation and peroxisomal biogenesis are controlled by nonhomologous regulators, OAF1/PIP2 in S. cerevisiae and FarA/FarB in A. nidulans; C. albicans is missing OAF1 and PIP2 and, instead, has a single homolog of the Far proteins, CTF1. We have shown that CTF1 is required for growth on lipids and for expression of genes necessary for β-oxidation, such as FOX2. ctf1Δ/ctf1Δ (ctf1Δ/Δ) strains do not, however, show the pleiotropic phenotypes observed for fox2Δ/Δ mutants. The ctf1Δ/Δ mutant confers a mild attenuation in virulence, like the fox2Δ/Δ mutant. Thus, phenotypic and genotypic observations highlight important differences in the regulatory network for alternative carbon metabolism in C. albicans compared to the paradigms developed in other model fungi.

scholarly journals Cloning and expression of genes encoding human pregnancy-specific glycoproteins.

1992 ◽  
Vol 267 (23) ◽  
pp. 16371-16378
Author(s):  
K.J. Lei ◽  
A.D. Sartwell ◽  
C.J. Pan ◽  
J.Y. Chou
Keyword(s):  
Cloning And Expression ◽  
Human Pregnancy ◽  
Expression Of Genes ◽  
Genes Encoding

scholarly journals Kinetic characterisation and inhibitor sensitivity of Candida albicans and Candida auris recombinant AOX expressed in a self-assembled proteoliposome system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alice C. Copsey ◽  
Mario R. O. Barsottini ◽  
Benjamin May ◽  
Fei Xu ◽  
Mary S. Albury ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Future Development ◽  
Therapeutic Target ◽  
Fungicide Resistance ◽  
Alternative Oxidase ◽  
Antifungal Agents ◽  
Candida Auris ◽  
Novel Treatments ◽  
Membrane Bound ◽  
Self Assembled

AbstractCandidemia caused by Candida spp. is a serious threat in hospital settings being a major cause of acquired infection and death and a possible contributor to Covid-19 mortality. Candidemia incidence has been rising worldwide following increases in fungicide-resistant pathogens highlighting the need for more effective antifungal agents with novel modes of action. The membrane-bound enzyme alternative oxidase (AOX) promotes fungicide resistance and is absent in humans making it a desirable therapeutic target. However, the lipophilic nature of the AOX substrate (ubiquinol-10) has hindered its kinetic characterisation in physiologically-relevant conditions. Here, we present the purification and expression of recombinant AOXs from C. albicans and C. auris in a self-assembled proteoliposome (PL) system. Kinetic parameters (Km and Vmax) with respect to ubiquinol-10 have been determined. The PL system has also been employed in dose–response assays with novel AOX inhibitors. Such information is critical for the future development of novel treatments for Candidemia.

scholarly journals The Early Transcriptional Response of Human Granulocytes to Infection with Candida albicans Is Not Essential for Killing but Reflects Cellular Communications

2006 ◽  
Vol 75 (3) ◽  
pp. 1493-1501 ◽  
Author(s):  
Chantal Fradin ◽  
Abigail L. Mavor ◽  
Günther Weindl ◽  
Martin Schaller ◽  
Karin Hanke ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Mononuclear Cells ◽  
De Novo ◽  
Transcriptional Response ◽  
Mononuclear Leukocytes ◽  
General Notion ◽  
Genes Encoding ◽  
Global Transcriptional Profile ◽  
Life Threatening ◽  
Systemic Infections

ABSTRACT Candida albicans is a polymorphic opportunistic fungus that can cause life-threatening systemic infections following hematogenous dissemination in patients susceptible to nosocomial infection. Neutrophils form part of the innate immune response, which is the first line of defense against microbes and is particularly important in C. albicans infections. To compare the transcriptional response of leukocytes exposed to C. albicans, we investigated the expression of key cytokine genes in polymorphonuclear and mononuclear leukocytes after incubation with C. albicans for 1 h. Isolated mononuclear cells expressed high levels of genes encoding proinflammatory signaling molecules, whereas neutrophils exhibited much lower levels, similar to those observed in whole blood. The global transcriptional profile of neutrophils was examined by using an immunology-biased human microarray to determine whether different morphological forms or the viability of C. albicans altered the transcriptome. Hyphal cells appeared to have the broadest effect, although the most strongly induced genes were regulated independently of morphology or viability. These genes were involved in proinflammatory cell-cell signaling, cell signal transduction, and cell growth. Generally, genes encoding known components of neutrophil granules showed no upregulation at this time point; however, lactoferrin, a well-known candidacidal peptide, was secreted by neutrophils. Addition to inhibitors of RNA or protein de novo synthesis did not influence the killing activity within 30 min. These results support the general notion that neutrophils do not require gene transcription to mount an immediate and direct attack against microbes. However, neutrophils exposed to C. albicans express genes involved in communication with other immune cells.

scholarly journals RegA, an AraC-Like Protein, Is a Global Transcriptional Regulator That Controls Virulence Gene Expression in Citrobacter rodentium

2008 ◽  
Vol 76 (11) ◽  
pp. 5247-5256 ◽  
Author(s):  
Emily Hart ◽  
Ji Yang ◽  
Marija Tauschek ◽  
Michelle Kelly ◽  
Matthew J. Wakefield ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Virulence Gene ◽  
Virulence Determinants ◽  
Intestinal Colonization ◽  
Citrobacter Rodentium ◽  
Promoter Regions ◽  
Reading Frame ◽  
Virulence Gene Expression ◽  
Genes Encoding ◽  
Colonization Factors

ABSTRACT Citrobacter rodentium is an attaching and effacing pathogen which causes transmissible colonic hyperplasia in mice. Infection with C. rodentium serves as a model for infection of humans with enteropathogenic and enterohemorrhagic Escherichia coli. To identify novel colonization factors of C. rodentium, we screened a signature-tagged mutant library of C. rodentium in mice. One noncolonizing mutant had a single transposon insertion in an open reading frame (ORF) which we designated regA because of its homology to genes encoding members of the AraC family of transcriptional regulators. Deletion of regA in C. rodentium resulted in markedly reduced colonization of the mouse intestine. Examination of lacZ transcriptional fusions using promoter regions of known and putative virulence-associated genes of C. rodentium revealed that RegA strongly stimulated transcription of two newly identified genes located close to regA, which we designated adcA and kfcC. The cloned adcA gene conferred autoaggregation and adherence to mammalian cells to E. coli strain DH5α, and a kfc mutation led to a reduction in the duration of intestinal colonization, but the kfc mutant was far less attenuated than the regA mutant. These results indicated that other genes of C. rodentium whose expression required activation by RegA were required for colonization. Microarray analysis revealed a number of RegA-regulated ORFs encoding proteins homologous to known colonization factors. Transcription of these putative virulence determinants was activated by RegA only in the presence of sodium bicarbonate. Taken together, these results show that RegA is a global regulator of virulence in C. rodentium which activates factors that are required for intestinal colonization.

Sign in / Sign up

Export Citation Format

Share Document