Role of major facilitator superfamily transporter Qdr2p in biofilm formation by Candida glabrata

Abstract

Summary Candida glabrata represents the second‐most frequent cause of candidiasis infections of the mucosa, bloodstream and genito‐urinary tract in immunocompromised individuals. The incidence of C glabrata infection has increased significantly in the last two decades, mainly due to this species’ abilities to resist various antifungal drugs and to form biofilms. We focused on the relationship between biofilm formation and the product of QDR2, a C glabrata member of the major facilitator superfamily (MFS) gene family, given that fungal biofilm formation limits drug penetration and is associated with persistent infection. The fungal cells in biofilms were compared between a C glabrata ∆qdr2 mutant and its wild‐type strain. Cells were analysed for metabolism activity and drug susceptibility (using tetrazolium assay), adhesion activity, growth assay and intracellular pH (using flow cytometry). Compared to the wild type, the C glabrata ∆qdr2 showed lower adhesion activity and higher fluconazole susceptibility when assessed as a biofilm. The mutant also showed decreased metabolic activity during biofilm formation. Furthermore, the mutant grew more slowly under neutral‐basic pH conditions. The qdr2 deletion in C glabrata resulted in an impaired ability to maintain pH homeostasis, which led in turn to a reduction of cell growth and of adherence to an artificial matrix. These results suggested that the Qdr2p function is needed for proper biofilm formation and biofilm maintenance in C glabrata as well as biofilm drug resistance towards fluconazole. Qdr2p may play an important role in C glabrata's ability to form biofilms on implanted medical devices in human bodies.

Screening the Drug:H+ Antiporter Family for a Role in Biofilm Formation in Candida glabrata

“…Four, Out of the 10, Drug:H + Antiporters in C. glabrata Are Required for Biofilm Development Given the previous implication of CgQdr2 and CgTpo1_2 in biofilm formation in C. glabrata Widiasih Widiyanto et al, 2019), a systematic analysis of the possible involvement of all DHA1 transporters in this pathogenic yeast was carried out. The ability of the KUE100 wild-type strain and derived deletion mutants cgaqr1, cgqdr2, cgtpo1_1, cgtpo1_2, cgtpo3, cgtpo4, cgflr1_1, cgflr1_2, cgyhk8, and cgdrt1 to form biofilms was assessed in SDB pH 5.6 and RPMI pH 4 media, on polystyrene, by the crystal-violet assay.…”

“…CgDtr1 has a role in the survival upon phagocytosis, being necessary for the resistance to oxidative and acetic acid stress . More recently, CgQdr2 was also identified as playing a role in biofilm formation, although the underlying mechanisms remained elusive (Widiasih Widiyanto et al, 2019). All the roles described for MFS transporters highlight their promiscuity in transporting many different substrates, which appear to ultimately lead to unexpected roles in processes, such as virulence, immune system evasion, or biofilm formation.…”

The Lack of SNARE Protein Homolog Syn8 Influences Biofilm Formation of Candida glabrata

“…C. glabrata biofilms were formed according to an in vitro method using a 96-well flat-bottom polystyrene plate (IWAKI, Japan) (Widiasih Widiyanto et al, 2019). Yeast cells were cultured overnight at 37 • C. Cells were harvested by centrifugation and washed twice in 100 µL sterile phosphate-buffered saline buffer (PBS, 137 mmol/L NaCl, 2.7 mmol/L KCl, 10 mmol/L Na 2 HPO 4 , 2 mmol/L KH 2 PO 4 , pH 7.2).…”

“…In addition to proteins that act on cell wall synthesis related to the adhesion step during biofilm formation, some recent studies have reported that the multidrug resistance transporters Pdr16p and Tpo1_2p contribute to azole resistance and are related to biofilm formation (Culakova et al, 2013;Santos et al, 2017). More recently, Dtr1p, Qdr2p, and Tpo4p drug:H + antiporters were found to be associated with biofilm formation of C. glabrata (Widiasih Widiyanto et al, 2019;Santos et al, 2020). Thus, it seems like a broad range of proteins, which are valuable to study, affect the process of biofilm formation of C. glabrata.…”