Modulation of azole sensitivity and filamentation by GPI15, encoding a subunit of the first GPI biosynthetic enzyme, in Candida albicans

• Published in: Scientific reports 2019-06, Vol.9 (1), p.8508, Article 8508
• Main Authors: Jain, Priyanka, Garai, Pramita, Sethi, Subhash Chandra, Naqvi, Nilofer, Yadav, Bhawna, Kumar, Pravin, Singh, Sneh Lata, Yadav, Usha, Bhatnagar, Shilpi, Rahul, Puri, Niti, Muthuswami, Rohini, Komath, Sneha Sudha
• Format: Article
• Language: English
• Subjects: 13; 13/2; 13/31; 14/63; 38/1; 38/22; 38/77; 38/90; 42/34; 45/41; 631/326/193/2538; 631/80/221; 82/16; 82/29; Acetylation; Animals; Azoles; Azoles - pharmacology; Biosynthesis; Biosynthetic Pathways - drug effects; Candida albicans; Candida albicans - drug effects; Candida albicans - enzymology; Candida albicans - genetics; Candida albicans - growth & development; Cell Line; Cell lines; Cell Wall - drug effects; Cell Wall - metabolism; Chromosomes, Fungal - genetics; Enzymes; Epithelial cells; Epithelial Cells - drug effects; Epithelial Cells - microbiology; Ergosterol - biosynthesis; Filamentation; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal - drug effects; Genes, Fungal; Glycosylphosphatidylinositol; Glycosylphosphatidylinositols - metabolism; Heterozygote; Humanities and Social Sciences; Hyphae - drug effects; Macrophages; Macrophages - drug effects; Macrophages - metabolism; Mice; Morphogenesis; multidisciplinary; Mutants; Mutation - genetics; N-Acetylglucosinyldiphosphodolichol N-acetylglucosaminyltransferase; Phagocytosis - drug effects; Phenotype; Protein Subunits - genetics; Protein Subunits - metabolism; Saccharomyces cerevisiae - metabolism; Science; Science (multidisciplinary); Signal Transduction - drug effects; Virulence; Virulence - drug effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-44919-4

Glycosylphosphatidylinositol (GPI)-anchored proteins are important for virulence of many pathogenic organisms including the human fungal pathogen, Candida albicans . GPI biosynthesis is initiated by a multi-subunit enzyme, GPI- N- acetylglucosaminyltransferase (GPI-GnT). We showed previously that two GPI-GnT subunits, encoded by CaGPI2 and CaGPI19 , are mutually repressive. CaGPI19 also co-regulates CaERG11 , the target of azoles while CaGPI2 controls Ras signaling and hyphal morphogenesis. Here, we investigated the role of a third subunit. We show that CaGpi15 is functionally homologous to Saccharomyces cerevisiae Gpi15. CaGPI15 is a master activator of CaGPI2 and CaGPI19 . Hence, CaGPI15 mutants are azole-sensitive and hypofilamentous. Altering CaGPI19 or CaGPI2 expression in CaGPI15 mutant can elicit alterations in azole sensitivity via CaERG11 expression or hyphal morphogenesis, respectively. Thus, CaGPI2 and CaGPI19 function downstream of CaGPI15 . One mode of regulation is via H3 acetylation of the respective GPI-GnT gene promoters by Rtt109. Azole sensitivity of GPI-GnT mutants is also due to decreased H3 acetylation at the CaERG11 promoter by Rtt109. Using double heterozygous mutants, we also show that CaGPI2 and CaGPI19 can independently activate CaGPI15 . CaGPI15 mutant is more susceptible to killing by macrophages and epithelial cells and has reduced ability to damage either of these cell lines relative to the wild type strain, suggesting that it is attenuated in virulence.