Targeting Ngt1-mediated GlcNAc transport in Candida albicans: An in silico approach for antifungal therapy

This is the authors' abstract. We don't add key points for this paper.

The commensal yeast, Candida albicans , has the enormous metabolic flexibility to utilize alternative carbon sources such as N-acetylglucosamine (GlcNAc) at infection sites, thereby facilitating its adaptive strategies to colonize and thrive in diverse host niches. In Candida , the GlcNAc specific transporter (Ngt1) imports GlcNAc at cell surface to induce signaling through the master regulator Ngs1 at the chromatin level. Thus, GlcNAc signaling is responsible for changing its habitat from commensal to pathogenic life style. The current study aims to understand the expression, structural and functional intricacies of Ngt1 that determines the GlcNAc sensitivity, specificity, and its transport which is a prerogatory step in the GlcNAc signaling process in Candida. Expression kinetics was analyzed using fluorescent microscopy and immunoblot. The 3D structure of Ngt1 was predicted using AlphaFold. Docking studies were carried out using AutoDock suite for native and Site directed mutant versions of Ngt1 with GlcNAc to determine the role of critical amino acids and further, tunnel analysis to reveal the transport mechanism. These findings lead to the designing structure-based Ngt1 blockers via virtual screening of natural compound libraries. Fluorescence microscopy and immunoblot analysis of Ngt1-GFPɤ analyses indicated GlcNAc sensitivity and prolific nature of NGT1 expression. The docking studies of Ngt1 with GlcNAc revealed the useful insights into the mechanism and the role of critical amino acids (Ala 324, Ile 325, Tyr 329, and Asp 332) responsible for interaction. In our analysis, Asn 195, located within the transmembrane helix and part of the UNC-93-like transmembrane regulatory protein domain, was identified as a critical residue for GlcNAc interaction compared with other mutated residues. Interestingly, the tunnel analysis of the Ngt1 transporter revealed the presence of potential pathways in Ngt1 protein for effective GlcNAc transport. This study provides basic insights into the structural aspects of Ngt1 and its interaction with GlcNAc that can be further explored for the development of effective therapeutic agents for control of infection caused by the Candida. Structural and functional analysis of Ngt1 protein. Flow chart depicting Ngt1 3D modeling (AlphaFold2), docking studies of Ngt1-wild type and SDM proteins with GlcNAc ligand, tunnel analysis reflecting transport of GlcNAc, and virtual screening to identify potential inhibitors (Brucine).