Dataset Information

Cryptococcus neoformans senses CO2 through the carbonic anhydrase Can2 and the adenylyl cyclase Cac1.

ABSTRACT: Cryptococcus neoformans, a fungal pathogen of humans, causes fatal meningitis in immunocompromised patients. Its virulence is mainly determined by the elaboration of a polysaccharide capsule surrounding its cell wall. During its life, C. neoformans is confronted with and responds to dramatic variations in CO2 concentrations; one important morphological change triggered by the shift from its natural habitat (0.033% CO2) to infected hosts (5% CO2) is the induction of capsule biosynthesis. In cells, CO2 is hydrated to bicarbonate in a spontaneous reaction that is accelerated by carbonic anhydrases. Here we show that C. neoformans contains two beta-class carbonic anhydrases, Can1 and Can2. We further demonstrate that CAN2, but not CAN1, is abundantly expressed and essential for the growth of C. neoformans in its natural environment, where CO2 concentrations are limiting. Structural studies reveal that Can2 forms a homodimer in solution. Our data reveal Can2 to be the main carbonic anhydrase and suggest a physiological role for bicarbonate during C. neoformans growth. Bicarbonate directly activates the C. neoformans Cac1 adenylyl cyclase required for capsule synthesis. We show that this specific activation is optimal at physiological pH.

SUBMITTER: Mogensen EG

PROVIDER: S-EPMC1360268 | biostudies-literature | 2006 Jan

REPOSITORIES: biostudies-literature

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Cryptococcus neoformans senses CO2 through the carbonic anhydrase Can2 and the adenylyl cyclase Cac1.

Mogensen Estelle Geweiss EG Janbon Guilhem G Chaloupka James J Steegborn Clemens C Fu Man Shun MS Moyrand Frédérique F Klengel Torsten T Pearson David S DS Geeves Michael A MA Buck Jochen J Levin Lonny R LR Mühlschlegel Fritz A FA

Eukaryotic cell 20060101 1

Cryptococcus neoformans, a fungal pathogen of humans, causes fatal meningitis in immunocompromised patients. Its virulence is mainly determined by the elaboration of a polysaccharide capsule surrounding its cell wall. During its life, C. neoformans is confronted with and responds to dramatic variations in CO2 concentrations; one important morphological change triggered by the shift from its natural habitat (0.033% CO2) to infected hosts (5% CO2) is the induction of capsule biosynthesis. In cells ...[more]

PMID: 16400172

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Project description:Carbon dioxide (CO2) sensing, transport, and metabolism play a pivotal role in survival and proliferation of pathogenic microbes infecting human host from natural environments due to the drastic difference of CO2 levels. Carbonic anhydrases (CAs) are not only key CO2-metabolic enzymes catalyzing reversible interconversion between CO2 and bicarbonate (HCO3-), but also important CO2-signaling modulators. Cryptococcus neoformans that causes fatal fungal meningitis contains two functional CAs, Can1 and Can2, among which Can2 plays essential roles for growth and sexual differentiation of the pathogen. However, downstream genes and signaling network regulated by CAs have not been studied thus far. In this study, we constructed a C. neoformans strain where CAN2 expression is controlled by the CTR4 (copper transporter) promoter and elucidated its transcriptome patterns by using DNA microarray analysis to elucidate downstream target genes of Can2. Expectedly, the CAN2 promoter replacement strain showed growth defects in a CO2-dependent manner when CAN2 is repressed. The CA-transcriptome analysis discovered a number of Can2-dependent genes, including those involved in fatty acid biosynthesis (FAS1), sexual differentiation (GPB1), capsule structure organization (CAS3), iron-metabolism (CFO2), and a number of stress-regulated genes, including an oxidative stress-responsive Atf1 transcription factor, although a majority of them do not have any orthologs in other fungi. The present study revealed other roles of Atf1 in capsule and melanin production and diverse stress responses, including thermotolerance and antifungal drug resistance, of C. neoformans. This study provides further insights into the signaling network of CA/CO2-sensing pathway in pathogenic fungi. 17 slides are used in this analysis, 3 or 2 biological replicate experiments are performed, total RNAs are extracted from 2 strains (H99 Wild type strain, CTR4::CAN2) at 2 time points (0hr time, 12hr time) in 2 conditions (BCS, CuSO4). We use the mixed all of total RNAs from this experiment as a control RNA. We use Cy5 as Sample dye and Cy3 as a control dye. Several experiment samples are dye swaped.

Dataset Information

Cryptococcus neoformans senses CO2 through the carbonic anhydrase Can2 and the adenylyl cyclase Cac1.

Publications

Cryptococcus neoformans senses CO2 through the carbonic anhydrase Can2 and the adenylyl cyclase Cac1.

Similar Datasets

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