Heteronuclear NMR studies of metabolites produced byCryptococcus neoformans in culture media: Identification of possible virulence factors

Bubb, William A.; Wright, Lesley C.; Cagney, Michelle; Santangelo, Rosemary T.; Sorrell, Tania C.; Kuchel, Philip W.

doi:10.1002/(sici)1522-2594(199909)42:3<442::aid-mrm6>3.0.co;2-q

Cited by 44 publications

(5 citation statements)

References 45 publications

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“…The metabolites observed are in agreement with those identified in previous C. neoformans metabolomics studies, which have reported dominance of trehalose and lipids (Bubb et al 1999; Himmelreich et al 2001). Trehalose is also associated with capacity to grow at 37° (Petzold et al 2006) and increased levels of trehalose have been associated with heat tolerant mutants of Cryptococcus (Morrow et al 2012), in agreement with the increased capacity of F2 for growth at this temperature.…”

Section: Resultssupporting

confidence: 91%

Comparative Genomics of Serial Isolates of Cryptococcus neoformans Reveals Gene Associated With Carbon Utilization and Virulence

Ormerod

Morrow

Chow

et al. 2013

G3 Genes|Genomes|Genetics

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The opportunistic fungal pathogen Cryptococcus neoformans is a leading cause of mortality among the human immunodeficiency virus/acquired immunodeficiency syndrome population and is known for frequently causing life-threatening relapses. To investigate the potential contribution of in-host microevolution to persistence and relapse, we have analyzed two serial isolates obtained from a patient with acquired immunodeficiency syndrome who suffered an initial and relapse episode of cryptococcal meningoencephalitis. Despite being identical by multilocus sequence typing, the isolates differ phenotypically, exhibiting changes in key virulence factors, nutrient acquisition, metabolic profiles, and the ability to disseminate in an animal model. Whole-genome sequencing uncovered a clonal relationship, with only a few unique differences. Of these, two key changes are expected to explain the phenotypic differences observed in the relapse isolate: loss of a predicted AT-rich interaction domain protein and changes in copy number of the left and right arms of chromosome 12. Gene deletion of the predicted transcriptional regulator produced changes in melanin, capsule, carbon source use, and dissemination in the host, consistent with the phenotype of the relapse isolate. In addition, the deletion mutant displayed altered virulence in the murine model. The observed differences suggest the relapse isolate evolved subsequent to penetration of the central nervous system and may have gained dominance following the administration of antifungal therapy. These data reveal the first molecular insights into how the Cryptococcus neoformans genome changes during infection of humans and the manner in which microevolution progresses in this deadly fungal pathogen.

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Section: Resultssupporting

confidence: 91%

Comparative Genomics of Serial Isolates of Cryptococcus neoformans Reveals Gene Associated With Carbon Utilization and Virulence

Ormerod

Morrow

Chow

et al. 2013

G3 Genes|Genomes|Genetics

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“…Although C. neoformans is a non-fermenting yeast, it releases significant amounts of acetate during host infection [ 41 , 42 ]. Although routes of acetate production have not been fully characterized in C. neoformans, several studies suggest that acetate is produced by the conversion of pyruvate to acetaldehyde and by the diversion of early intermediates of glycolysis into the phosphoketolase pathway [ 13 , 43 ] ( Figure 5 ).…”

Section: Discussionmentioning

confidence: 99%

“…However, no NAD + is regenerated via these pathways. In contrast to mammalian cells, very little lactate is produced by C. neoformans [ 41 , 42 ]. Another source of growth medium acidification by cryptococcal cells is the activity of P-type H + -ATPase.…”

Section: Discussionmentioning

confidence: 99%

Monitoring Glycolysis and Respiration Highlights Metabolic Inflexibility of Cryptococcus neoformans

Lev

Desmarini

et al. 2020

Pathogens

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Cryptococcus neoformans is a human fungal pathogen that adapts its metabolism to cope with limited oxygen availability, nutrient deprivation and host phagocytes. To gain insight into cryptococcal metabolism, we optimized a protocol for the Seahorse Analyzer, which measures extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indications of glycolytic and respiratory activities. In doing so we achieved effective immobilization of encapsulated cryptococci, established Rotenone/Antimycin A and 2-deoxyglucose as effective inhibitors of mitochondrial respiration and glycolysis, respectively, and optimized a microscopy-based method of data normalization. We applied the protocol to monitor metabolic changes in the pathogen alone and in co-culture with human blood-derived monocytes. We also compared metabolic flux in wild-type C. neoformans, its isogenic 5-PP-IP5/IP7-deficient metabolic mutant kcs1∆, the sister species of C. neoformans, Cryptococcus deuterogattii/VGII, and two other yeasts, Saccharomyces cerevisiae and Candida albicans. Our findings show that in contrast to monocytes and C. albicans, glycolysis and respiration are tightly coupled in C. neoformans and C. deuterogattii, as no compensatory increase in glycolysis occurred following inhibition of respiration. We also demonstrate that kcs1∆ has reduced metabolic activity that correlates with reduced mitochondrial function. Metabolic inflexibility in C. neoformans is therefore consistent with its obligate aerobe status and coincides with phagocyte tolerance of ingested cryptococcal cells.

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“…The acidification of the cryptococcoma is believed to result from production of acetate by the organisms, which lowers the pH [14]. Thus, there is a gradient from physiological pH (pH = 7.34–7.4) at the periphery to a pH as low as 5.6 in the center of the cryptococcoma [13].…”

Section: Introductionmentioning

confidence: 99%

An Acidic Microenvironment Increases NK Cell Killing of Cryptococcus neoformans and Cryptococcus gattii by Enhancing Perforin Degranulation

Islam

Oykhman

et al. 2013

PLoS Pathog

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Cryptococcus gattii and Cryptococcus neoformans are encapsulated yeasts that can produce a solid tumor-like mass or cryptococcoma. Analogous to malignant tumors, the microenvironment deep within a cryptococcoma is acidic, which presents unique challenges to host defense. Analogous to malignant cells, NK cells kill Cryptococcus. Thus, as in tumor defense, NK cells must kill yeast cells across a gradient from physiologic pH to less than 6 in the center of the cryptococcoma. As acidic pH inhibits anti-tumor activities of NK cells, we sought to determine if there was a similar reduction in the anticryptococcal activity of NK cells. Surprisingly, we found that both primary human NK cells and the human NK cell line, YT, have preserved or even enhanced killing of Cryptococcus in acidic, compared to physiological, pH. Studies to explore the mechanism of enhanced killing revealed that acidic pH does not increase the effector to target ratio, binding of cytolytic cells to Cryptococcus, or the active perforin content in effector cells. By contrast, perforin degranulation was greater at acidic pH, and increased degranulation was preceded by enhanced ERK1/2 phosphorylation, which is essential for killing. Moreover, using a replication defective ras1 knockout strain of Cryptococcus increased degranulation occurred during more rapid replication of the organisms. Finally, NK cells were found intimately associated with C. gattii within the cryptococcoma of a fatal infection. These results suggest that NK cells have amplified signaling, degranulation, and greater killing at low pH and when the organisms are replicating quickly, which would help maintain microbicidal host defense despite an acidic microenvironment.

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Heteronuclear NMR studies of metabolites produced byCryptococcus neoformans in culture media: Identification of possible virulence factors

Cited by 44 publications

References 45 publications

Comparative Genomics of Serial Isolates of Cryptococcus neoformans Reveals Gene Associated With Carbon Utilization and Virulence

Comparative Genomics of Serial Isolates of Cryptococcus neoformans Reveals Gene Associated With Carbon Utilization and Virulence

Monitoring Glycolysis and Respiration Highlights Metabolic Inflexibility of Cryptococcus neoformans

An Acidic Microenvironment Increases NK Cell Killing of Cryptococcus neoformans and Cryptococcus gattii by Enhancing Perforin Degranulation

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