Inositol Phosphoryl Transferase, Ipt1, Is a Critical Determinant of Azole Resistance and Virulence Phenotypes in Candida glabrata

Garima Shahi; Mohit Kumar; Nitesh Kumar Khandelwal; Atanu Banerjee; Parijat Sarkar; Sonam Kumari; Brooke D Esquivel; Neeraj Chauhan; Amitabha Chattopadhyay; Theodore C White; Naseem A Gaur; Ashutosh Singh; Rajendra Prasad

doi:10.3390/jof8070651

Inositol Phosphoryl Transferase, Ipt1, Is a Critical Determinant of Azole Resistance and Virulence Phenotypes in Candida glabrata

J Fungi (Basel). 2022 Jun 21;8(7):651. doi: 10.3390/jof8070651.

Authors

Affiliations

¹ Amity Institute of Biotechnology and Integrative Science and Health, Amity University Gurgaon, Gurgaon 122412, India.
² Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India.
³ Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA.
⁴ CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India.
⁵ School of Biological and Chemical Sciences, University of Missouri at Kansas City, Kansas City, MO 64110, USA.
⁶ Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA.
⁷ Department of Biochemistry, University of Lucknow, Lucknow 226007, India.

Abstract

In this study, we have specifically blocked a key step of sphingolipid (SL) biosynthesis in Candida glabrata by disruption of the orthologs of ScIpt1 and ScSkn1. Based on their close homology with S. cerevisiae counterparts, the proteins are predicted to catalyze the addition of a phosphorylinositol group onto mannosyl inositolphosphoryl ceramide (MIPC) to form mannosyl diinositolphosphoryl ceramide (M(IP)₂C), which accounts for the majority of complex SL structures in S. cerevisiae membranes. High throughput lipidome analysis confirmed the accumulation of MIPC structures in ΔCgipt1 and ΔCgskn1 cells, albeit to lesser extent in the latter. Noticeably, ΔCgipt1 cells showed an increased susceptibility to azoles; however, ΔCgskn1 cells showed no significant changes in the drug susceptibility profiles. Interestingly, the azole susceptible phenotype of ΔCgipt1 cells seems to be independent of the ergosterol content. ΔCgipt1 cells displayed altered lipid homeostasis, increased membrane fluidity as well as high diffusion of radiolabeled fluconazole (³H-FLC), which could together influence the azole susceptibility of C. glabrata. Furthermore, in vivo experiments also confirmed compromised virulence of the ΔCgipt1 strain. Contrarily, specific functions of CgSkn1 remain unclear.

Keywords: Candida glabrata; drug resistance; inositolphosphorylceramide; lipidomics; sphingolipids; virulence.

Grants and funding

RP acknowledges support from ICMR (AMR/149 (2)-2018-ECD-II), RP, AS and AB from DBT (BT/PR38505/MED/29/1513/2020). AS thanks support from ICMR (No.52/08/2019-BIO/BMS), DST-PURSE program (SR/PURSE Phase 2/29©), UP Higher Education (No. 10/2021/281/-4-Sattar-2021-04(2)/2021), and the University of Lucknow. NAG acknowledges ICGEB, New Delhi, and Department of Biotechnology (DBT), Government of India for financial support (Grant No.: BT/PB/Centre/03/ICGEB/2011-PhaseII). APC was covered by the Journal of Fungi Editorial Office.