GPI (glycosylphosphatidylinositol)-linked aspartyl proteases regulate vacuole homoeostasis in <i>Candida glabrata</i>

Bairwa, Gaurav; Rasheed, Mubashshir; Taigwal, Ritu; Sahoo, Rosalin; Kaur, Rupinder

doi:10.1042/bj20130757

Cited by 31 publications

(69 citation statements)

References 49 publications

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“…5A). Of note, growth of C. glabrata mutants (Cgstv1 and Cgvma13) disrupted for the vacuolar proton-transporting V-type ATPase remained unaffected in the presence of elevated extracellular concentrations of potassium and ferric ions (29). These data indicate that despite elevated metal ion susceptibility, growth attenuation of the Cgvps34⌬ mutant in the high-iron environment could not solely be due to the dysfunctional vacuole.…”

Section: Intracellular Levels Of Zinc Calcium and Manganese Are Notmentioning

confidence: 60%

“…First, metal ion sensitivity profile of the Cgvps34⌬ mutant appears to be distinct (Fig. 5, A and B) from the one reported for vacuolar ATPase-defective mutants (29). Second, there was no appreciable competition among metal ions for the nonspecific transporter-dependent uptake (Fig.…”

Section: Discussionmentioning

confidence: 79%

“…Other Procedures-qPCR, THP-1 macrophage infection, intracellular ROS determination, ATP level determination, and serial dilution spotting assay were performed as described previously (12,29,35).…”

Section: Methodsmentioning

confidence: 99%

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The Phosphoinositide 3-Kinase Regulates Retrograde Trafficking of the Iron Permease CgFtr1 and Iron Homeostasis in Candida glabrata

Sharma

Purushotham

Kaur

2016

Journal of Biological Chemistry

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Edited by James SiedowThe phosphoinositide 3-kinase (PI3K), which phosphorylates phosphatidylinositol and produces PI3P, has been implicated in protein trafficking, intracellular survival, and virulence in the pathogenic yeast Candida glabrata. Here, we demonstrate PI3-kinase (CgVps34) to be essential for maintenance of cellular iron homeostasis. We examine how CgVps34 regulates the fundamental process of iron acquisition, and underscore its function in vesicular trafficking as a central determinant. RNA sequencing analysis revealed iron homeostasis genes to be differentially expressed upon CgVps34 disruption. Consistently, the Cgvps34⌬ mutant displayed growth attenuation in low-and high-iron media, increased intracellular iron content, elevated mitochondrial aconitase activity, impaired biofilm formation, and extenuated mouse organ colonization potential. Furthermore, we demonstrate for the first time that C. glabrata cells respond to iron limitation by expressing the iron permease CgFtr1 primarily on the cell membrane, and to iron excess via internalization of the plasma membrane-localized CgFtr1 to the vacuole. Our data show that CgVps34 is essential for the latter process. We also report that macrophage-internalized C. glabrata cells express CgFtr1 on the cell membrane indicative of an iron-restricted macrophage internal milieu, and Cgvps34⌬ cells display better survival in iron-enriched medium-cultured macrophages. Overall, our data reveal the centrality of PI3K signaling in iron metabolism and host colonization.

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Section: Intracellular Levels Of Zinc Calcium and Manganese Are Notmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 79%

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The Phosphoinositide 3-Kinase Regulates Retrograde Trafficking of the Iron Permease CgFtr1 and Iron Homeostasis in Candida glabrata

Sharma

Purushotham

Kaur

2016

Journal of Biological Chemistry

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“…The Crz1 ortholog in C. neoformans influences growth at high temperature, the response to oxygen limitation, cell wall biosynthesis, fluconazole sensitivity, and biofilm formation in a calcium-dependent manner (92,93). In this context, it is interesting that recent work with Candida glabrata revealed that the aspartyl protease CgYps1 (yapsin 1) influences vacuolar and ion homeostasis, cell wall remodelling, calcineurin sensitivity, and polyphosphate levels (94). When combined with our results and the connections between the PHO pathway, calcineurin, and cAMP signaling in A. fumigatus (49), these observations suggest that a conserved regulatory network exists in fungi that involves cross talk between phosphate metabolism, PKA, and calcineurin.…”

Section: Discussionmentioning

confidence: 99%

Defects in Phosphate Acquisition and Storage Influence Virulence of Cryptococcus neoformans

et al. 2014

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Nutrient acquisition and sensing are critical aspects of microbial pathogenesis. Previous transcriptional profiling indicated that the fungal pathogen Cryptococcus neoformans, which causes meningoencephalitis in immunocompromised individuals, encounters phosphate limitation during proliferation in phagocytic cells. We therefore tested the hypothesis that phosphate acquisition and polyphosphate metabolism are important for cryptococcal virulence. Deletion of the high-affinity uptake system interfered with growth on low-phosphate medium, perturbed the formation of virulence factors (capsule and melanin), reduced survival in macrophages, and attenuated virulence in a mouse model of cryptococcosis. Additionally, analysis of nutrient sensing functions for C. neoformans revealed regulatory connections between phosphate acquisition and storage and the iron regulator Cir1, cyclic AMP (cAMP)-dependent protein kinase A (PKA), and the calcium-calmodulin-activated protein phosphatase calcineurin. Deletion of the VTC4 gene encoding a polyphosphate polymerase blocked the ability of C. neoformans to produce polyphosphate. The vtc4 mutant behaved like the wild-type strain in interactions with macrophages and in the mouse infection model. However, the fungal load in the lungs was significantly increased in mice infected with vtc4 deletion mutants. In addition, the mutant was impaired in the ability to trigger blood coagulation in vitro, a trait associated with polyphosphate. Overall, this study reveals that phosphate uptake in C. neoformans is critical for virulence and that its regulation is integrated with key signaling pathways for nutrient sensing.

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“…Changes in lipid composition of the Cgcrz1⌬ mutant might affect the activity of membrane proteins essential for barrier function (50,51). The deletion of CgCRZ1 might have the following effects: (i) a reduction of CgYPS1 mRNA levels, thus affecting Pma1p and pH homeostasis under acidic conditions (52,53), (ii) a decrease in ELO3 mRNA levels, thus affecting biosynthesis and maturation of very-long-chain (C 26 ) fatty acids that control Pma1p biogenesis (54), and (iii) a decrease in the activity of membrane H ϩ -ATPase, which pumps protons out of yeast cells at a low pH (55). Our results suggest that manipulating the plasma membrane lipid composition is a novel strategy for improving growth under acid stress conditions.…”

Section: Discussionmentioning

confidence: 99%

Crz1p Regulates pH Homeostasis in Candida glabrata by Altering Membrane Lipid Composition

Yan

Lin

et al. 2016

Appl Environ Microbiol

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The asexual facultative aerobic haploid yeast Candida glabrata is widely used in the industrial production of various organic acids. To elucidate the physiological function of the C. glabrata transcription factor Crz1p (CgCrz1p) and its role in tolerance to acid stress, we deleted or overexpressed the corresponding gene, CgCRZ1. Deletion of CgCRZ1 resulted in a 60% decrease in the dry weight of cells (DCW) and a 50% drop in cell viability compared with those of the wild type at pH 2.0. Expression of lipid metabolism-associated genes was also significantly downregulated. Consequently, the proportion of C 18:1 fatty acids, the ratio of unsaturated to saturated fatty acids, and the ergosterol content decreased by 30%, 46%, and 30%, respectively. Additionally, membrane integrity, fluidity, and H ؉ -ATPase activity were reduced by 45%, 9%, and 50%, respectively. In contrast, overexpression of CgCrz1p increased C 18:1 and ergosterol contents by 16% and 40%, respectively. Overexpression also enhanced membrane integrity, fluidity, and H ؉ -ATPase activity by 31%, 6%, and 20%, respectively. Moreover, in the absence of pH buffering, the DCW and pyruvate titers increased by 48% and 60%, respectively, compared to that of the wild type. Together, these results suggest that CgCrz1p regulates tolerance to acidic conditions by altering membrane lipid composition in C. glabrata. IMPORTANCEThis study provides insight into the metabolism of Candida glabrata under acidic conditions, such as those encountered during the industrial production of organic acids. We found that overexpression of the transcription factor CgCrz1p improved viability, biomass, and pyruvate yields at a low pH. Analysis of plasma membrane lipid composition indicated that CgCrz1p might play an important role in its integrity and fluidity and that it enhanced the pumping of protons in acidic environments. We propose that altering the structure of the cell membrane may provide a successful strategy for increasing C. glabrata productivity at a low pH.T he asexual facultative aerobic haploid yeast Candida glabrata is the only microorganism used for the industrial production of pyruvic (1), fumaric (2), malic (3), and ␣-ketoglutaric (4) acids. However, the accumulation of extracellular acid causes a significant reduction in the pH of the fermentation broth, thereby inhibiting cell growth and decreasing the synthesis of the target compound (5). To maintain the culture medium at a suitable pH, alkaline reagents, such as NaOH, Na 2 CO 3 , and CaCO 3 , are added, although this can result in increased osmotic stress (6). Improving the tolerance of C. glabrata to low-pH conditions should boost the economic efficiency of organic acid production. Various approaches have been attempted in this sense, including the addition of exogenous auxiliary energy substrates (7), chemical mutagenesis of microorganisms (8), rational genetic engineering (9), and adaptive evolution (10). Such approaches have achieved improvements in the titer and yield of some target organic acids ...

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GPI (glycosylphosphatidylinositol)-linked aspartyl proteases regulate vacuole homoeostasis in Candida glabrata

Cited by 31 publications

References 49 publications

The Phosphoinositide 3-Kinase Regulates Retrograde Trafficking of the Iron Permease CgFtr1 and Iron Homeostasis in Candida glabrata

The Phosphoinositide 3-Kinase Regulates Retrograde Trafficking of the Iron Permease CgFtr1 and Iron Homeostasis in Candida glabrata

Defects in Phosphate Acquisition and Storage Influence Virulence of Cryptococcus neoformans

Crz1p Regulates pH Homeostasis in Candida glabrata by Altering Membrane Lipid Composition

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