Identification of a basidiomycete-specific Vilse-like GTPase activating proteins (GAPs) and its roles in the production of virulence factors in Cryptococcus neoformans

Abstract

Cryptococcus neoformans is a basidiomycetous pathogenic yeast that causes fatal infections in both immunocompetent and immunocompromised patients. Regulation on the production of its virulence factors is not fully understood. Here we reported the characterization of a gene, named CVH1(CNA06260), encoding a Drosophila Vilse-like RhoGAP homolog, which is hallmarked by three conserved functional domains: WW, MyTH4 and RhoGAP. Phylogenetic analysis suggests that CVH1 is highly conserved from protists to mammals and interestingly in basidiomycetes, but absent in plants or Ascomycota and other lower fungi. This phylogenetic distribution indicates an evolutionary link among these groups of organisms. Functional analyses demonstrated that CVH1 was involved in stress tolerance and virulence factor production. By disrupting CVH1, we created a second mutant cvh1Δ with the CRISPR-Cas9 editing tool. The mutant strain exhibited hypersensitivity to osmotic stress by 2 M sorbitol and NaCl, suggesting defects in the HOG signaling pathway and an interaction of Cvh1 with the HOG pathway. Hypersensitivity of cvh1Δ to 1% Congo red and 0.01% SDS suggests that the cell wall integrity was impaired in the mutant. And cvh1Δ hardly produced the pigment melanin and capsule. Our study for the first time demonstrates that the fungal Vilse-like RhoGAP CVH1 is an important regulator of multiple biological processes in C. neoformans, and provides novel insights into the regulatory circuit of stress resistance/cell wall integrity, and laccase and capsule synthesis in C. neoformans.

The cAMP/Protein Kinase A Pathway Regulates Virulence and Adaptation to Host Conditions in Cryptococcus neoformans

“…These results provide evidence of cross talk between the CWI and cAMP/PKA pathways for the regulation of cell wall and capsule production (Donlin et al, 2014). Another example comes from the recent characterization of the Cryptococcus Vilse homolog (Cvh1), a protein that is highly homologous to the Rho GAP-containing Vilse protein in Drosophila melanogaster (Rahim et al, 2017). This putative RhoGAP protein is important for capsule and melanin formation, and cvh1 mutants exhibit hypersensitivity to osmotic stress, heat shock and cell wall stressors, suggesting a role in regulatory circuits that govern CWI (Rahim et al, 2017).…”

“…Another example comes from the recent characterization of the Cryptococcus Vilse homolog (Cvh1), a protein that is highly homologous to the Rho GAP-containing Vilse protein in Drosophila melanogaster (Rahim et al, 2017). This putative RhoGAP protein is important for capsule and melanin formation, and cvh1 mutants exhibit hypersensitivity to osmotic stress, heat shock and cell wall stressors, suggesting a role in regulatory circuits that govern CWI (Rahim et al, 2017). Interestingly, addition of exogenous cAMP restores melanin but not capsule formation to the cvh1 mutant.…”

Genome-Wide Identification of circRNAs in Pathogenic Basidiomycetous Yeast Cryptococcus neoformans Suggests Conserved circRNA Host Genes over Kingdoms

“…The expression level of global circRNAs in the DBR1Δ mutant strain increased by three- to four-fold over the level in the wild-type (WT) S. pombe [ 31 ]. To investigate the function of DBR1 in circRNA regulation in C. neoformans , we tried to knock out the counterpart DBR1 gene in C. neoformans JEC21 with the latest clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 editing system [ 32 , 33 ]. Unfortunately, we failed to get any DBR1 knockout strain, which implies that the DBR1 gene might be essential in serotype D strains.…”

Identification of Low Temperature Inducible Genes of Lactuca sativa by Using Suppression Subtractive Hybridization Method

“…Rho GTPase-activating protein was reported to be involved in the regulation of tolerance to dehydration stress in barley (Suprunova et al, 2007). Although very little information is available on this protein in plants, Rho GTPase-activating protein in yeast has been reported to be an important regulator of multiple biological process including stress resistance and so on (Rahim et al, 2017). This protein might play an important role for response to low temperature stress in lettuce.…”