Karine Dementhon

University of Bordeaux · Department of Life and Health Sciences

Survival of the pathogenic yeast Candida albicans depends upon assimilation of fermentable and non-fermentable carbon sources detected in host microenvironments. Among the various carbon sources encountered in a human body, glucose is the primary source of energy. Its effective detection, metabolism and prioritization via glucose repression are pri...

During Candida macrophage interactions, phagocytosed yeast cells feed in order to grow, develop hyphae and escape. Through numerous proteomic and transcriptomic studies, two metabolic phases have been described. A shift to a starvation mode is generally identified as early as one-hour post phagocytosis, followed by a glycolytic growth mode after C....

The pathogenic yeast Candida albicans is both a powerful commensal and a pathogen of humans that can infect wide range of organs and body sites. Metabolic flexibility promotes infection and commensal colonization by this opportunistic pathogen. Yeast cell survival depends upon assimilation of fermentable and non-fermentable locally available carbon...

Metabolic flexibility promotes infection and commensal colonization by the opportunistic pathogen Candida albicans. Yeast cell survival depends upon assimilation of fermentable and non-fermentable locally available carbon sources. Physiologically relevant sugars like glucose and fructose are present at low level in host niches. However, because glu...

Clavispora lusitaniae , an environmental saprophytic yeast belonging to the CTG clade of Candida , can behave occasionally as an opportunistic pathogen in humans. We report here the genome sequence of the type strain CBS 6936. Comparison with sequences of strain ATCC 42720 indicates conservation of chromosomal structure but significant nucleotide d...

Hybrid histidine kinases (HHKs) progressively emerge as prominent sensing proteins in the fungal kingdom and as ideal targets for future therapeutics. The group X HHK is of major interest, since it was demonstrated to play an important role in stress adaptation, host-pathogen interactions and virulence in some yeast and mold models, and particularl...

The fungal cell wall contains glycoproteins that interact with the host immune system. In the prominent pathogenic yeast Candida albicans, Pmr1 acts as a Golgi-resident ion pump that provides cofactors to mannosyltransferases, regulating the synthesis of mannans attached to glycoproteins. To gain insight into a putative conservation of such a cruci...

Introduction Les cellules phagocytaires des lignées monocytaire et neutrophile sont essentielles à la défense de l’organisme au cours d’une infection à Candida spp. Cependant in vitro, C. albicans, C. glabrata et C. lusitaniae sont capables de résister à la phagocytose. Notre hypothèse est que les lipides, et en particulier les acides gras, pourrai...

It is generally admitted that the ascomycete yeasts of the subphylum Saccharomycotina possess a single fatty acid beta-oxidation pathway located exclusively in peroxisomes, and that they lost mitochondrial beta-oxidation early during evolution. In this work, we showed that mutants of the opportunistic pathogenic yeast Candida lusitaniae which lack...

We characterized two additional membrane transporters (Fur4p and Dal4p) of the nucleobase cation symporter 1 (NCS1) family involved in the uptake transport of pyrimidines and related molecules in the opportunistic pathogenic yeast Candida lusitaniae. Simple and multiple null mutants were constructed by gene deletion and genetic crosses. The functio...

Candida lusitaniae is an emerging opportunistic yeast and an attractive model to discover new virulence factors in Candida species by reverse genetics. Our goal was to create a dpp3Δ knockout mutant and to characterize the effects of this gene inactivation on yeast in vitro and in vivo interaction with the host. The secretion of two signaling molec...

We developed a new in vitro model for a multi-parameter characterization of the time course interaction of Candida fungal cells with J774 murine macrophages and human neutrophils, based on the use of combined microscopy, fluorometry, flow cytometry and viability assays. Using fluorochromes specific to phagocytes and yeasts, we could accurately quan...

Representative pictures of the J774 macrophages after 5 hours of infection with the three Candida species in culture flasks at 1M:1Y MOI. Note that the totality of C. glabrata cells were engulfed, whereas C. albicans (mostly in filamentous form) and C. lusitaniae cells were still observed outside the macrophages. The scale bars represent 30 µm. See...

Video-microscopy observation of J774 macrophages infected with C. albicans at 1M:1Y MOI. (AVI)

Macrophage cell death is not due to a nutritional depletion of the medium during infection. The quantity of glucose available was measured in the supernatant of the J774 macrophages that were infected with live or UV-killed yeasts of the three Candida species for 5 and 24 hours at a MOI of 1M:1Y (Method S1), and compared to uninfected macrophages,...

Macrophages viability in cRPMI medium with and without CFW (5 µg/ml) by calcein fluorescence measurements. Each bar is the average of two experiments ± standard error. (TIF)

Calcein fluorescence varies proportionaly with the number of macrophages. Each bar is the average of three experiments ± standard error. (TIF)

Yeast cells muliplication over time by OD600nm and CFW fluorescence measurements in cRPMI medium with 5 µg/ml of CFW. Dashed lines show linear regression lines, and their slopes are indicated. (TIF)

Analysis of the interactions involving the J774 macrophages and stationary-phase living yeast cells at 1M:1Y MOI over 24-hour time course experiments. Figure S5 details how the diagram of Figure 3A was built. Figure S5A shows the flow cytometry analysis of the macrophages and corresponds to the left part of the diagram of Figure 3A. Each bar repres...

Macrophage fungicidal activity toward the different Candida species. To investigate the capacity of the macrophages to kill the different species of Candida, the survival of the yeast cells was determined following 5 and 24 hours of incubation with phagocytic cells at a 1M:1Y MOI (Method S2). 100% of the C. albicans cells survived, while 20% and 40...

Method involved in glucose assay. See Table S1. (DOC)

Method documenting the survival of ingested yeasts. See Figure S7. (DOC)

Video-microscopy observation of J774 macrophages infected with C. lusitaniae at 1M:2Y MOI. (AVI)

Video-microscopy observation of J774 macrophages infected with C. glabrata at 1M:5Y MOI. (AVI)

Yeast cells multiplication in cRPMI medium with and without CFW (5 µg/ml) by OD600nm measurements. C.a: C.albicans, C.g: C.glabrata, C.l: C.lusitaniae. (TIF)

We describe a new cloning-free strategy to delete genes in the opportunistic pathogenic yeast Candida lusitaniae. We first constructed two ura3 Δ strains in C. lusitaniae for their use in transformation experiments. One was deleted for the entire URA3 coding sequence; the other possessed a partial deletion within the coding region, which was used t...

The phytopathogen Pseudomonas syringae competes with other epiphytic organisms, such as filamentous fungi, for resources. Here we characterize a gene in P. syringae pv. syringae B728a and P. syringae pv. tomato DC3000, termed phcA, that has homology to a filamentous fungal gene called het-c. phcA is conserved in many P. syringae strains, but is abs...

Non-self recognition resulting in programmed cell death is a ubiquitous phenomenon in filamentous ascomycete fungi and is termed heterokaryon incompatibility (HI). Recent analyses show that genes containing predicted HET domains are often involved in HI; however, the function of the HET domain is unknown. Autophagy is induced as a consequence of HI...

Nonself recognition during somatic growth is an essential and ubiquitous phenomenon in both prokaryotic and eukaryotic species. In filamentous fungi, nonself recognition is also important during vegetative growth. Hyphal fusion between genetically dissimilar individuals results in rejection of heterokaryon formation and in programmed cell death of...

Nonself recognition in filamentous fungi is conferred by genetic differences at het (heterokaryon incompatibility) loci. When individuals that differ in het specificity undergo hyphal fusion, the heterokaryon undergoes a programmed cell death reaction or is highly unstable. In Neurospora crassa, three allelic specificities at the het-c locus are co...

Heterokaryon incompatibility is a cell destruction process that occurs when fungal cells of unlike genotype fuse. In Podospora anserina, autophagy is engaged during cell death by incompatibility and a number of genes are induced at the transcriptional level. These genes are termed idi (induced during incompatibility) genes. Among these is idi-4, a...

In filamentous fungi a cell death reaction occurs when hyphae of unlike genotype fuse. This phenomenon is referred to as heterokaryon incompatibility. In Podospora anserina, this cell death reaction was found to be associated with the transcriptional induction of a set of genes termed idi genes (for induced during incompatibility) and activation of...

In filamentous fungi, a programmed cell death (PCD) reaction occurs when cells of unlike genotype fuse. This reaction is caused by genetic differences at specific loci termed het loci (for heterokaryon incompatibility). Although several het genes have been characterized, the mechanism of this cell death reaction and its relation to PCD in higher eu...

In filamentous fungi, a cell death reaction occurs when cells of unlike genotype fuse. This cell death reaction, known as incompatibility reaction, is genetically controlled by a set of loci termed het loci (for heterokaryon incompatibility loci). In Podospora anserina, genes induced during this cell death reaction (idi genes) have been identified....