Metabolic fitness of Candida albicans is indispensable for functional drug efflux, ergosterol, and chitin biosynthesis

Document Type : Original Articles


Amity Institute of Biotechnology, Amity University Haryana, Gurugram (Manesar)-122413, India


Background and Purpose: The increment in fungal infections, particularly due to Candida species, is alarming due to the emergence of multidrug resistance (MDR). Hence, the identification of novel drug targets to circumvent the problem of MDR requires immediate attention. The metabolic pathway, such as glyoxylate cycle (GC), which utilizes key enzymes (isocitrate lyase [ICL] and malate synthase [MLS]), enables C. albicans to adapt under glucose-deficient conditions. This study uncovers the effect of GC disruption on the major MDR mechanisms of C. albicans as a human pathogenic fungus.
Materials and Methods: For the purpose of the study, efflux pump activity was assessed by phenotypic susceptibilities in the presence of substrates rhodamine 6G (R6G) and Nile red, along with R6G extracellular concentration (527 nm). In addition, ergosterol content was estimated by the alcoholic potassium hydroxide hydrolysis method. The estimation of chitin was also accomplished by the absorbance (520 nm) of glucosamine released by acid hydrolysis.
Results: The results revealed that the disruption of ICL enzyme gene (Δicl1) led to the impairment of the efflux activity of multidrug transporters belonging to the ATP-binding cassette superfamily. It was further shown that Δicl1 mutant exhibited diminished ergosterol and chitin contents. In addition, all abrogated phenotypes could be rescued in the reverting strain of Δicl1 mutant.
Conclusion: Based on the findings, the disruption of GC affected efflux activity and the synthesis of ergosterol and chitin. The present study for the first time revealed that metabolic fitness was associated with functional drug efflux, ergosterol and chitin biosynthesis and validated GC as an antifungal target. However, further studies are needed to comprehend and exploit this therapeutic opportunity.


1. Singh S, Fatima Z, Hameed S. Predisposing factors endorsing Candida infections. Infez Med. 2015; 23(3):211-23.
2. Perlroth J, Choi B, Spellberg B. Nosocomial fungal infections: epidemiology, diagnosis, and treatment. Med Mycol. 2007; 45(4):321-46.
3. Tanwar J, Das S, Fatima Z, Hameed S. Multidrug resistance: an emerging crisis. Interdiscip Perspect Infect Dis. 2014; 2014:541340.
4. Arendrup MC, Patterson TF. Multidrug-resistant Candida: epidemiology, molecular mechanisms, and treatment. J Infect Dis. 2017; 216(Suppl 3): S445-51.
5. Dunn MF, Ramírez-Trujillo JA, Hernández-Lucas I. Major roles of isocitrate lyase and malate synthase in bacterial and fungal pathogenesis. Microbiology. 2009; 155(Pt 10):3166-75.
6. Kastora SL, Herrero-de-Dios C, Avelar GM, Munro CA, Brown AJ. Sfp1 and Rtg3 reciprocally modulate carbon source-conditional stress adaptation in the pathogenic yeast Candida albicans. Mol Microbiol. 2017; 105(4):620-36.
7. Han L, Reynolds KA. A novel alternate anaplerotic pathway to the glyoxylate cycle in streptomycetes. J Bacteriol. 1997; 179(16):5157-64.
8. Prado RS, Alves RJ, Oliveira CM, Kato L, Silva RA, Quintino GO, et al. Inhibition of Paracoccidioides lutzii Pb01 isocitrate lyase by the natural compound argentilactone and its semi-synthetic derivatives. PLoS One. 2014; 9(4):e94832.
9. Ansari MA, Fatima Z, Hameed S. Glyoxylate cycle: a promising antimicrobial drug target. New Delhi: Daya Publishing House; 2016. P. 333-43.
10. Lorenz MC, Fink GR. Life and death in a macrophage: role of the glyoxylate cycle in virulence. Eukaryot Cell. 2002; 1(5):657-62.
11. Lorenz MC, Fink GR. The glyoxylate cycle is required for
fungal virulence. Nature. 2001; 412(6842):83-6.
12. Ramirez MA, Lorenz MC. Mutations in alternative carbon utilization pathways in Candida albicans attenuate virulence and confer pleiotropic phenotypes. Eukaryot Cell. 2007; 6(2):280-90.
13. Ansari MA, Fatima Z, Hameed S. Anticandidal effect and mechanisms of monoterpenoid, perillyl alcohol against Candida albicans. PLoS One. 2016; 11(9):e0162465.
14. Singh S, Fatima Z, Hameed S. Citronellal induced disruption of membrane homeostasis and attenuation of its virulence traits. Rev Soc Bras Med Trop. 2016; 49(4):465-72.
15. Yang F, Kravets A, Bethlendy G, Welle S, Rustchenko E. Chromosome 5 monosomy of Candida albicans controls susceptibility to various toxic agents, including major antifungals. Antimicrob Agents Chemother. 2017; 57(10):5026-36.
16. Prasad R, Balzi E, Banerjee A, Khandelwal NK. All about Candida drug resistance CDRs: past, present and future. Yeast. 2019; 36(4):223-33.
17. Prasad R, Banerjee A, Khandelwal NK, Dhamgaye S. The ABCs of Candida albicans multidrug transporter Cdr1. Eukaryot Cell. 2015; 14(12):1154-64.
18. Ramage G, Bachmann S, Patterson TF, Wickes BL, López-Ribot JL. Investigation of multidrug efflux pumps in relation to fluconazole resistance in Candida albicans biofilms. J Antimicrob Chemother. 2002; 49:973-80.
19. Prasad R, Rawal MK. Efflux pump proteins in antifungal resistance. Front Pharmacol. 2014; 5:202.
20. Cabezón V, Llama-Palacios A, Nombela C, Monteoliva L, Gil C. Nombela C. Analysis of Candida albicans plasma membrane proteome. Proteomics. 2009; 9(20):4770-86.
21. Suchodolski J, Muraszko J, Bernat P, Krasowska A. A crucial role for ergosterol in plasma membrane composition, Localisation, and activity of Cdr1p and H+-ATPase in Candida albicans. Microorganisms. 2019; 7(10):378.
22. Pasrija R, Panwar SL, Prasad R. Multidrug transporters CaCdr1p and CaMdr1p of Candida albicans display different lipid specificities: both ergosterol and sphingolipids are essential for targeting of CaCdr1p to membrane rafts. Antimicrob Agents Chemother. 2008; 52(2):694-704.
23. Walker LA, Gow NA, Munro CA. Elevated chitin content reduces the susceptibility of Candida species to caspofungin. Antimicrob Agents Chemother. 2013; 57(1):146-54.
24. Walker LA, Munro CA, de Bruijn I, Lenardon MD, McKinnon A, Gow NA. Stimulation of chitin synthesis rescues Candida albicans from echinocandins. PLoS Pathog. 2008; 4(4):e1000040.
Volume 6, Issue 3
September 2020
Pages 9-14
  • Receive Date: 29 April 2020
  • Revise Date: 03 June 2020
  • Accept Date: 20 June 2020
  • First Publish Date: 01 September 2020