Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.
PLoS One. 2022 Jul 12;17(7):e0269721. doi: 10.1371/journal.pone.0269721. eCollection 2022.
This study was designed to understand the molecular mechanisms of azole resistance in Candida tropicalis using genetic and bioinformatics approaches. Thirty-two azole-resistant and 10 azole-susceptible (S) clinical isolates of C. tropicalis were subjected to mutation analysis of the azole target genes including ERG11. Inducible expression analysis of 17 other genes potentially associated with azole resistance was also evaluated. Homology modeling and molecular docking analysis were performed to study the effect of amino acid alterations in mediating azole resistance. Of the 32 resistant isolates, 12 (37.5%) showed A395T and C461T mutations in the ERG11 gene. The mean overexpression of CDR1, CDR3, TAC1, ERG1, ERG2, ERG3, ERG11, UPC2, and MKC1 in resistant isolates without mutation (R-WTM) was significantly higher (p<0.05) than those with mutation (R-WM) and the sensitive isolates (3.2-11 vs. 0.2-2.5 and 0.3-2.2 folds, respectively). Although the R-WTM and R-WM had higher (p<0.05) CDR2 and MRR1 expression compared to S isolates, noticeable variation was not seen among the other genes. Protein homology modelling and molecular docking revealed that the mutations in the ERG11 gene were responsible for structural alteration and low binding efficiency between ERG11p and ligands. Isolates with ERG11 mutations also presented A220C in ERG1 and together T503C, G751A mutations in UPC2. Nonsynonymous mutations in the ERG11 gene and coordinated overexpression of various genes including different transporters, ergosterol biosynthesis pathway, transcription factors, and stress-responsive genes are associated with azole resistance in clinical isolates of C. tropicalis.
本研究旨在通过遗传和生物信息学方法研究热带念珠菌唑类耐药的分子机制。对 32 株唑类耐药和 10 株唑类敏感（S）临床分离株的唑类靶基因（包括 ERG11）进行突变分析。还评估了其他 17 个可能与唑类耐药相关的基因的诱导表达分析。进行同源建模和分子对接分析，以研究介导唑类耐药的氨基酸改变的影响。在 32 株耐药分离株中，有 12 株（37.5%）在 ERG11 基因中出现 A395T 和 C461T 突变。无突变（R-WTM）的耐药分离株中 CDR1、CDR3、TAC1、ERG1、ERG2、ERG3、ERG11、UPC2 和 MKC1 的平均过表达明显高于有突变（R-WM）和敏感分离株（3.2-11 倍比 0.2-2.5 和 0.3-2.2 倍）。尽管 R-WTM 和 R-WM 与 S 分离株相比 CDR2 和 MRR1 表达更高（p<0.05），但其他基因之间没有明显差异。蛋白质同源建模和分子对接表明 ERG11 基因的突变导致结构改变和 ERG11p 与配体之间的结合效率降低。具有 ERG11 突变的分离株也在 ERG1 中出现 A220C，并且在 UPC2 中同时出现 T503C 和 G751A 突变。ERG11 基因中的非同义突变和各种基因的协调过表达，包括不同的转运蛋白、麦角固醇生物合成途径、转录因子和应激反应基因，与热带念珠菌临床分离株的唑类耐药有关。
