Limits...
Role of an expanded inositol transporter repertoire in Cryptococcus neoformans sexual reproduction and virulence.

Xue C, Liu T, Chen L, Li W, Liu I, Kronstad JW, Seyfang A, Heitman J - MBio (2010)

Bottom Line: Expression of ITR genes in a Saccharomyces cerevisiae itr1 itr2 mutant lacking inositol transport can complement the slow-growth phenotype of this strain, confirming that ITR genes are bona fide inositol transporters.Deletion of the inositol 1-phosphate synthase gene INO1 in an itr1 or itr1a mutant background compromised virulence in a murine inhalation model, indicating the importance of inositol sensing and acquisition for fungal infectivity.Our study provides a platform for further understanding the roles of inositol in fungal physiology and virulence.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA.

ABSTRACT
Cryptococcus neoformans and Cryptococcus gattii are globally distributed human fungal pathogens and the leading causes of fungal meningitis. Recent studies reveal that myo-inositol is an important factor for fungal sexual reproduction. That C. neoformans can utilize myo-inositol as a sole carbon source and the existence of abundant inositol in the human central nervous system suggest that inositol is important for Cryptococcus development and virulence. In accord with this central importance of inositol, an expanded myo-inositol transporter (ITR) gene family has been identified in Cryptococcus. This gene family contains two phylogenetically distinct groups, with a total of 10 or more members in C. neoformans and at least six members in the sibling species C. gattii. These inositol transporter genes are differentially expressed under inositol-inducing conditions based on quantitative real-time PCR analyses. Expression of ITR genes in a Saccharomyces cerevisiae itr1 itr2 mutant lacking inositol transport can complement the slow-growth phenotype of this strain, confirming that ITR genes are bona fide inositol transporters. Gene mutagenesis studies reveal that the Itr1 and Itr1A transporters are important for myo-inositol stimulation of mating and that functional redundancies among the myo-inositol transporters likely exist. Deletion of the inositol 1-phosphate synthase gene INO1 in an itr1 or itr1a mutant background compromised virulence in a murine inhalation model, indicating the importance of inositol sensing and acquisition for fungal infectivity. Our study provides a platform for further understanding the roles of inositol in fungal physiology and virulence.

No MeSH data available.


Related in: MedlinePlus

Mating stimulation is myo-inositol specific. (A) Mating assays between strains H99 and KN99a were performed in MS medium containing different carbon sources at a concentration of 100 mg/liter, including myo-inositol, glucose, galactose, glycerol, or sucrose. No other tested carbon source except myo-inositol stimulated fungal mating. (B) Mating assays were performed in MS medium containing different inositol isomers, including myo-, scyllo-, allo-, muco-, and chiro-inositol. No other isomers except myo-inositol stimulated mating at a concentration of 100 mg/liter. (C and D) Mating assays were performed in MS medium containing 50 mg/liter (C) or 20 mg/liter (D) myo-inositol and 100 mg/liter of each other form, such as scyllo-, allo-, muco-, or chiro-inositol. The presence of allo-, muco-, or chiro-inositol competed with myo-inositol and inhibited mating. No obvious inhibition by scyllo-inositol was observed. (E) Structures of the inositol isomers studied.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2912663&req=5

f1: Mating stimulation is myo-inositol specific. (A) Mating assays between strains H99 and KN99a were performed in MS medium containing different carbon sources at a concentration of 100 mg/liter, including myo-inositol, glucose, galactose, glycerol, or sucrose. No other tested carbon source except myo-inositol stimulated fungal mating. (B) Mating assays were performed in MS medium containing different inositol isomers, including myo-, scyllo-, allo-, muco-, and chiro-inositol. No other isomers except myo-inositol stimulated mating at a concentration of 100 mg/liter. (C and D) Mating assays were performed in MS medium containing 50 mg/liter (C) or 20 mg/liter (D) myo-inositol and 100 mg/liter of each other form, such as scyllo-, allo-, muco-, or chiro-inositol. The presence of allo-, muco-, or chiro-inositol competed with myo-inositol and inhibited mating. No obvious inhibition by scyllo-inositol was observed. (E) Structures of the inositol isomers studied.

Mentions: Because myo-inositol is the main carbon source in MS medium, we replaced myo-inositol with other carbon sources, including glucose, sucrose, galactose, and glycerol. None of those sugars stimulated mating at the same concentration, indicating that myo-inositol elicits mating in addition to its known ability to serve as a carbon source (Fig. 1A).


Role of an expanded inositol transporter repertoire in Cryptococcus neoformans sexual reproduction and virulence.

Xue C, Liu T, Chen L, Li W, Liu I, Kronstad JW, Seyfang A, Heitman J - MBio (2010)

Mating stimulation is myo-inositol specific. (A) Mating assays between strains H99 and KN99a were performed in MS medium containing different carbon sources at a concentration of 100 mg/liter, including myo-inositol, glucose, galactose, glycerol, or sucrose. No other tested carbon source except myo-inositol stimulated fungal mating. (B) Mating assays were performed in MS medium containing different inositol isomers, including myo-, scyllo-, allo-, muco-, and chiro-inositol. No other isomers except myo-inositol stimulated mating at a concentration of 100 mg/liter. (C and D) Mating assays were performed in MS medium containing 50 mg/liter (C) or 20 mg/liter (D) myo-inositol and 100 mg/liter of each other form, such as scyllo-, allo-, muco-, or chiro-inositol. The presence of allo-, muco-, or chiro-inositol competed with myo-inositol and inhibited mating. No obvious inhibition by scyllo-inositol was observed. (E) Structures of the inositol isomers studied.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2912663&req=5

f1: Mating stimulation is myo-inositol specific. (A) Mating assays between strains H99 and KN99a were performed in MS medium containing different carbon sources at a concentration of 100 mg/liter, including myo-inositol, glucose, galactose, glycerol, or sucrose. No other tested carbon source except myo-inositol stimulated fungal mating. (B) Mating assays were performed in MS medium containing different inositol isomers, including myo-, scyllo-, allo-, muco-, and chiro-inositol. No other isomers except myo-inositol stimulated mating at a concentration of 100 mg/liter. (C and D) Mating assays were performed in MS medium containing 50 mg/liter (C) or 20 mg/liter (D) myo-inositol and 100 mg/liter of each other form, such as scyllo-, allo-, muco-, or chiro-inositol. The presence of allo-, muco-, or chiro-inositol competed with myo-inositol and inhibited mating. No obvious inhibition by scyllo-inositol was observed. (E) Structures of the inositol isomers studied.
Mentions: Because myo-inositol is the main carbon source in MS medium, we replaced myo-inositol with other carbon sources, including glucose, sucrose, galactose, and glycerol. None of those sugars stimulated mating at the same concentration, indicating that myo-inositol elicits mating in addition to its known ability to serve as a carbon source (Fig. 1A).

Bottom Line: Expression of ITR genes in a Saccharomyces cerevisiae itr1 itr2 mutant lacking inositol transport can complement the slow-growth phenotype of this strain, confirming that ITR genes are bona fide inositol transporters.Deletion of the inositol 1-phosphate synthase gene INO1 in an itr1 or itr1a mutant background compromised virulence in a murine inhalation model, indicating the importance of inositol sensing and acquisition for fungal infectivity.Our study provides a platform for further understanding the roles of inositol in fungal physiology and virulence.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA.

ABSTRACT
Cryptococcus neoformans and Cryptococcus gattii are globally distributed human fungal pathogens and the leading causes of fungal meningitis. Recent studies reveal that myo-inositol is an important factor for fungal sexual reproduction. That C. neoformans can utilize myo-inositol as a sole carbon source and the existence of abundant inositol in the human central nervous system suggest that inositol is important for Cryptococcus development and virulence. In accord with this central importance of inositol, an expanded myo-inositol transporter (ITR) gene family has been identified in Cryptococcus. This gene family contains two phylogenetically distinct groups, with a total of 10 or more members in C. neoformans and at least six members in the sibling species C. gattii. These inositol transporter genes are differentially expressed under inositol-inducing conditions based on quantitative real-time PCR analyses. Expression of ITR genes in a Saccharomyces cerevisiae itr1 itr2 mutant lacking inositol transport can complement the slow-growth phenotype of this strain, confirming that ITR genes are bona fide inositol transporters. Gene mutagenesis studies reveal that the Itr1 and Itr1A transporters are important for myo-inositol stimulation of mating and that functional redundancies among the myo-inositol transporters likely exist. Deletion of the inositol 1-phosphate synthase gene INO1 in an itr1 or itr1a mutant background compromised virulence in a murine inhalation model, indicating the importance of inositol sensing and acquisition for fungal infectivity. Our study provides a platform for further understanding the roles of inositol in fungal physiology and virulence.

No MeSH data available.


Related in: MedlinePlus