The human pathogenic yeast Candida glabrata harbors more than 20 surface-exposed, epithelial adhesins (Epas) for host cell adhesion. The Epa family recognizes host glycans and discriminates between target tissues by their adhesin (A) domains, but a detailed structural basis for ligand-binding specificity of Epa proteins has been lacking so far. In this study, we provide high-resolution crystal structures of the Epa1A domain in complex with different carbohydrate ligands that reveal how host cell mucin-type O-glycans are recognized and allow a structure-guided classification of the Epa family into specific subtypes. Further detailed structural and functional characterization of subtype-switched Epa1 variants shows that specificity is governed by two inner loops, CBL1 and CBL2, involved in calcium binding as well as by three outer loops, L1, L2, and L3. In summary, our study provides the structural basis for promiscuity and specificity of Epa adhesins, which might further contribute to developing anti-adhesive antimycotics and combating Candida colonization. molecular recognition | T-antigen | lectin | fungal pathogen

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Background:The pathogenic yeast Candida glabrata harbors more than 20 epithelial adhesins (Epas). Results: Epas are lectins with binding pockets that contain conserved and variable structural features determining ligand binding affinity and specificity. Conclusion: The functionally diverse Epa family evolved in C. glabrata for efficient host infection. Significance: Epa-mediated host-ligand binding is a therapeutic target to combat C. glabrata infections.

Abstract. Recent studies have demonstrated that inhibition of mevalonate synthesis in cultured cells leads to altered cell morphology due to inhibition of protein prenylation. To investigate the effects in vivo of mevalonate deprivation in nondividing, terminally differentiated neural cells, we have analyzed the effects on retinal tissue of intravitreal injection of lovastatin, a potent inhibitor of the mevalonate-producing enzyme, HMGCoA reductase. A single injection of lovastatin (0.25 ~mol) produced profound dysplastic-like changes in adult rat retinas primarily involving the photoreceptor layer. Within 2 d after injection, photoreceptor nuclei migrated in a circular pattern resulting in the formation of rosette-like structures by 4 d. Also during this period, photoreceptor inner and outer segment degeneration was evident. By 21 d, intact photoreceptor nuclei with remnants of inner and outer segments were dispersed throughout all retinal layers. To investigate the biochemical specificity of the lovastatin-induced alterations, and to distinguish the relative importance of the various branches of the mevalonate pathway, the incorpoTation of [3H]acetate into retinal lipids was examined in the presence and absence of metabolic inhibitors. HPLC analysis of lovastatin-treated retinas revealed a dramatic reduction in the incorporation of intravitreally injected [3H]acetate into nonsaponifiable lipids, compared with controls. In contrast, intravitreal injection of NB-598, a specific inhibitor of squalene epoxidase, eliminated the conversion of newly synthesized squalene to sterols without obvious pathology. Hence, involvement of the sterol branch of isoprenoid metabolism in the lovastatin-induced morphologic disruption was obviated. Intravitreal injection of 0.27 ixmol of N-acetyl-S-trans,trans-farnesyl-L-cysteine (AFC), an inhibitor of carboxyl methyltransferase activity and prenylated protein function, produced morphologic changes that were virtually indistinguishable from those induced with lovastatin. These results implicate a defect in protein prenylation in the lovastatin-induced retinal degeneration, and suggest the presence of a dynamic pathway in the retina that requires isoprenylated proteins to maintain retinal cytoarchitecture.

Fungal infections are a leading cause of morbidity and death for hospitalized patients, mainly because they remain difficult to diagnose and to treat. Diseases range from widespread superficial infections such as vulvovaginal infections to life-threatening systemic candidiasis. For systemic mycoses, only a restricted arsenal of antifungal agents is available. Commonly used classes of antifungal compounds include azoles, polyenes, and echinocandins. Due to emerging resistance to standard therapies, significant side effects, and high costs for several antifungals, there is a need for new antifungals in the clinic. In order to expand the arsenal of compounds with antifungal activity, we previously screened a compound library using a cell-based screening assay. A set of novel benzimidazole derivatives, including (S)-2-(1-aminoisobutyl)-1-(3-chlorobenzyl)benzimidazole (EMC120B12), showed high antifungal activity against several species of pathogenic yeasts, including Candida glabrata and Candida krusei (species that are highly resistant to antifungals). In this study, comparative analysis of EMC120B12 versus fluconazole and nocodazole, using transcriptional profiling and sterol analysis, strongly suggested that EMC120B12 targets Erg11p in the ergosterol biosynthesis pathway and not microtubules, like other benzimidazoles. In addition to the marker sterol 14-methylergosta-8,24(28)-dien-3␤,6␣-diol, indicating Erg11p inhibition, related sterols that were hitherto unknown accumulated in the cells during EMC120B12 treatment. The novel sterols have a 3␤,6␣-diol structure. In addition to the identification of novel sterols, this is the first time that a benzimidazole structure has been shown to result in a block of the ergosterol pathway.