Biology subjects

Petosa, C.

Publications and source records attributed to Petosa, C..

4 recordsLinked to original sources

bioRxiv2023

Targeting fungal BET bromodomains as a pan-Candida antifungal strategy

Small molecules that target one or both bromodomains (BDs) of human BET proteins are intensely studied as potential new therapeutics against cancer, diabetes and other diseases. The BDs of the fungal BET protein Bdf1 are essential for the human fungal pathogen Candida albicans, suggesting BET inhibition as a potential antifungal strategy. However, while the inactivation of both Bdf1 BDs is lethal, that of a single BD only modestly affects viability, implying the need to develop antifungal compounds that selectively target both Bdf1 BDs without inhibiting human BDs. Here, we investigate Bdf1 as a potential antifungal target in Candida glabrata, an invasive Candida species phylogenetically distant from C. albicans and of increasing medical concern. We show that Bdf1 BD functionality is essential in C. glabrata and identify a phenyltriazine derivative that targets both Bdf1 BDs with selectivity over human BET BDs. We show that human BET BDs can functionally replace Bdf1 BDs in C. glabrata and we use the humanized strains to demonstrate on-target antifungal activity of the phenyltriazine compound. Moreover, by exploiting the humanized and parental fungal strains we identified BET inhibitor I-BET726 to have potent antifungal activity against a broad spectrum of Candida species, including azole- and echinocandin-resistant clinical C. albicans and C. glabrata isolates. Crystal structures suggest how to improve the potency and selectivity of these compounds. Taken together, our findings provide compelling support for the development of BET inhibitors as potential pan-Candida antifungal therapeutics.

biochemistry↗

bioRxiv2023

Nucleoside Diphosphate Kinases 1 and 2 regulate a protective liver response to a high-fat diet

De novo lipogenesis (DNL), the process whereby cells synthesize fatty acids from acetyl-coenzyme A (acetyl-CoA), is deregulated in diverse pathologies, including cancer. Here we report that DNL is negatively regulated by Nucleoside Diphosphate Kinases 1 and 2 (NME1/2), housekeeping enzymes involved in nucleotide homeostasis that were recently discovered to bind co-enzyme A (CoA). We show that NME1 additionally binds acetyl-CoA and that ligand recognition involves a unique binding mode dependent on the CoA/acetyl-CoA 3 phosphate. We report that Nme2 knockout mice fed a high-fat diet (HFD) exhibit excessive triglyceride synthesis and liver steatosis. In liver cells NME2 mediates a gene transcriptional response to HFD leading to DNL repression and activation of a protective gene expression program via targeted histone acetylation. Our findings implicate NME1/2 in the epigenetic regulation of a protective liver response to HFD and suggest a potential role in controlling acetyl-CoA usage between the competing paths of histone acetylation and DNL.

molecular biology↗

bioRxiv2021

Differential Histone-DNA Interactions Dictate Nucleosome Recognition of the Pioneer Transcription Factor Sox

Pioneer transcription factors (PTFs) have the remarkable ability to directly bind to chromatin for stimulating vital cellular processes. In this work, we dissect the universal binding mode of Sox PTF by combining extensive molecular simulations and DNA footprinting techniques. As a result, we show that when Sox consensus DNA is located at the solvent-facing DNA strand, Sox binds to the compact nucleosome without imposing any significant conformational changes. We also reveal that the basespecific Sox:DNA interactions (base reading) and the Sox-induced DNA changes (shape reading) are concurrently required for the sequence-specific DNA recognition. Among different nucleosomal positions, such a specific reading mechanism is satisfied solely at superhelical location 2 (SHL2). While SHL2 acts transparently to Sox binding, SHL4 permits only shape reading, and SHL0 (dyad) allows no reading mechanism. These findings demonstrate for the first time that Sox-based nucleosome recognition is essentially guided by the distinct histone-DNA interactions, permitting varying degrees of DNA flexibility.

biophysics↗

bioRxiv2021

Binding stoichiometry and structural model of the HIV-1 Rev/Importin beta complex

HIV-1 Rev mediates the nuclear export of intron-containing viral RNA transcripts and is essential for viral replication. Rev is imported into the nucleus by the host protein Importin {beta} (Imp{beta}), but how Rev associates with Imp{beta} is poorly understood. Here we report biochemical, biophysical and structural studies of the Imp{beta}/Rev complex. Gel shift, native mass spectrometry and isothermal titration calorimetry data reveal that Imp{beta} binds two Rev monomers through independent binding sites. Small-angle X-ray scattering (SAXS) data suggest that the HEAT repeats of Imp{beta} retain an extended conformation upon binding Rev, which according to NMR data is primarily recognized through its helical hairpin domain. Peptide scanning data and charge-reversal mutations identify the N-terminal tip of Rev helix 2 within Revs Arginine-Rich Motif (ARM) as a primary Imp{beta} binding epitope. Crosslinking mass spectrometry and compensatory mutagenesis data combined with molecular docking simulations suggest a structural model in which one Rev monomer binds to the C-terminal half of Imp{beta} with Rev helix 2 roughly parallel to the HEAT-repeat superhelical axis while the other monomer binds to the N-terminal half. These findings shed light on the molecular basis of Rev recognition by Imp{beta} and highlight an atypical binding behaviour that distinguishes Rev from canonical cellular Imp{beta} cargos.

biochemistry↗