Identification and Phenotypic Characterization of Hsp90 Phosphorylation Sites That Modulate Virulence Traits in the Major Human Fungal Pathogen Candida albicans

Abstract

The highly conserved, ubiquitous molecular chaperone Hsp90 is a key regulator of cellular proteostasis and environmental stress responses. In human pathogenic fungi, which kill more than 1.6 million patients each year worldwide, Hsp90 governs cellular morphogenesis, drug resistance, and virulence. Yet, our understanding of the regulatory mechanisms governing fungal Hsp90 function remains sparse. Post-translational modifications are powerful components of nature’s toolbox to regulate protein abundance and function. Phosphorylation in particular is critical in many cellular signaling pathways and errant phosphorylation can have dire consequences for the cell. In the case of Hsp90, phosphorylation affects its stability and governs its interactions with co-chaperones and clients. Thereby modulating the cell’s ability to cope with environmental stress. Candida albicans, one of the leading human fungal pathogens, causes ~750,000 life-threatening invasive infections worldwide with unacceptably high mortality rates. Yet, it remains unknown if and how Hsp90 phosphorylation affects C. albicans virulence traits. Here, we show that phosphorylation of Hsp90 is critical for expression of virulence traits. We combined proteomics, molecular evolution analyses and structural modeling with molecular biology to characterize the role of Hsp90 phosphorylation in this non-model pathogen. We demonstrated that phosphorylation negatively affects key virulence traits, such as the thermal stress response, morphogenesis, and drug susceptibility. Our results provide the first record of a specific Hsp90 phosphorylation site acting as modulator of fungal virulence. Post-translational modifications of Hsp90 could prove valuable in future exploitations as antifungal drug targets.

Candidate effectors for leaf rust resistance gene Lr28 identified through transcriptome and in-silico analysis

“…However, for plant pathogens it is not established in detail, which otherwise might be critical for virulence. Four of these proteins have various role as: (i) stress-induced-phosphoprotein 1 {STIP1, also known as heat shock protein 70/90 (HSP70/90)} is known to regulate different cellular and physiological processes including cell morphology, drug resistance, and virulence in eukaryotes ( Singh et al, 2009 ; Alaalm et al, 2021 ). (ii) Acetyl-CoA acetyltransferase (encoded by Pt homologous CDS c55520_g1_i2), also denoted as ERG10 or Acetoacetyl-CoA thiolase or thiolases, contributes in biosynthesis of isopropanoid that expedites conversion of mevalonate to ergosterol through mevalonate pathway.…”

Anti-Cancer Properties of Ginkgolic Acids in Human Nasopharyngeal Carcinoma CNE-2Z Cells via Inhibition of Heat Shock Protein 90

“…In the present study, we observed that GAS had no significant effect on Hsp90 expression, which suggests that GAS inhibited Hsp90 ATPase activity and had no effect on protein expression. Several studies have reported that the activation of Hsp90 by phosphorylation is very important [35][36][37]. The phosphorylation of Hsp90 governs its interactions with co-chaperones and client proteins and could affect its stability.…”

Protein conformational ensembles in function: roles and mechanisms

“…The switch from the inactive to the active (and vice versa ) is driven by allostery. 59,87,88 Allostery can be triggered by noncovalent or covalent binding events, 88–112 leading to conformational and dynamic changes, 36,41,94,95,113–120 by inciting local energetic frustration, or conflicts. 25,121–123 Conformational changes relieving the frustration propagate in the structure, shifting the ensemble from the inactive toward the stable, minimally frustrated active state (Fig.…”