Biofilm matrix regulation by <i>Candida glabrata</i> Zap1 under acidic conditions: transcriptomic and proteomic analyses

The vaginal acidic environment potentiates the formation of <i>Candida glabrata</i> biofilms, leading to complicated and recurrent infections. Importantly, the production of matrix is known to contribute to the recalcitrant features of <i>Candida</i> biofilms. In this study, we reveal that Zap1 regulates the matrix of <i>C. glabrata</i> acidic biofilms and analyzed the modulation of their transcriptome (by microarrays) and matrix proteome (by LC-MS/MS) by Zap1. For that, the deletion mutant <i>zap1</i>Δ and its complemented strain <i>zap1</i>Δ::<i>ZAP1</i> were constructed, and their biofilms were developed at pH 4 (adjusted with lactic acid). The results revealed that Zap1 is a negative regulator of the total amount of protein and carbohydrate in the biofilm matrix. Accordingly, various genes and matrix proteins with predicted functions in the regulation of carbohydrate metabolism, sugar binding, sugar transport, and adhesion (including Epa family) were repressed by Zap1. Nevertheless, the results also suggested that Zap1 is essential to the delivery and organization of some matrix components. Indeed, Zap1 was required for the secretion of 122 proteins to the matrix and induced the expression of 557 genes, including various targets involved in glucan metabolism. Additionally, Zap1 induced targets with roles in virulence, resistance to antifungals, and host immunity evasion, including yapsins, <i>ERG</i> family, and moonlighting proteins. Zap1 was also required for the secretion of acidic-specific matrix proteins, indicating a contribution to the response to the acidic environment. Overall, this study demonstrates that Zap1 is a relevant regulator of the biofilm matrix, contributing to a better understanding of <i>C. glabrata</i> acidic biofilms.IMPORTANCEThe rising prevalence of vulvovaginal candidiasis (VVC) and the increasing presence of <i>Candida</i> spp. with aggressive virulence features and low susceptibility to common antifungals, particularly <i>Candida glabrata</i>, have resulted in more severe, prolonged, and recurrent cases of VVC, with significant implications for patients. This research offers valuable insights into the molecular changes that contribute to the formation of <i>C. glabrata</i> biofilms in the acidic vaginal environment, representing a significant advancement in the understanding of <i>C. glabrata</i>'s virulence. Notably, this study identified Zap1 as a critical regulator of <i>C. glabrata</i> biofilm matrix, with additional potential roles in adhesion, antifungal resistance, evasion of host immunity, and response to acidic conditions, making it a promising target for new therapeutic approaches. Importantly, Zap1 is the first regulator of the biofilm matrix to be identified in <i>C. glabrata</i>, and the elucidation of its targets (including genes and matrix proteins) lays a strong foundation for future research.