Genomic and functional analyses unveil the response to hyphal wall stress in Candida albicans cells lacking β(1,3)-glucan remodeling

Class 2: Transcripts that are less abundant in the phr1Δ mutant than in the wild type. (XLSX 39 kb

Iron-sulfur flavoenzymes: the added value of making the most ancient redox cofactors and the versatile flavins work together

Iron-sulfur (Fe-S) flavoproteins form a broad and growing class of complex, multi-domain and often multi-subunit proteins coupling the most ancient cofactors (the Fe-S clusters) and the most versatile coenzymes (the flavin coenzymes, FMN and FAD). These enzymes catalyse oxidoreduction reactions usually acting as switches between donors of electron pairs and acceptors of single electrons, and vice versa. Through selected examples, the enzymes' structure−function relationships with respect to rate and directionality of the electron transfer steps, the role of the apoprotein and its dynamics in modulating the electron transfer process will be discussed

Histone Demethylation Catalysed by LSD1 is a Flavin-dependent Oxidative Process

none5Lysine-specific histone demethylase 1 (LSD1) is a very recently discovered enzyme which specifically removes methyl groups from Lys4 of histone 3. We have addressed the functional properties of the protein demonstrating that histone demethylation involves the flavin-catalysed oxidation of the methylated lysine. The nature of the substrate that acts as the electron acceptor required to complete the catalytic cycle was investigated. LSD1 converts oxygen to hydrogen peroxide although this reactivity is not as pronounced as that of other flavin-dependent oxidases. Our findings raise the possibility that in vivo LSD1 might not necessarily function as an oxidase, but it might use alternative electron acceptors.Tematica Ex SIR: Istone demetilasi umana (Classif. Ex SIR:Articoli su riviste ISI )openForneris F; Binda C; Vanoni MA; Mattevi A; Battaglioli EForneris, Federico; Binda, Claudia; Vanoni, Ma; Mattevi, Andrea; Battaglioli, E

Key Role of the Adenylate Moiety and Integrity of the Adenylate-Binding Site for the NAD⁺/H Binding to Mitochondrial Apoptosis-Inducing Factor

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with pro-life and pro-death activities, which plays critical roles in mitochondrial energy metabolism and caspase-independent apoptosis. Defects in AIF structure or expression can cause mitochondrial abnormalities leading to mitochondrial defects and neurodegeneration. The mechanism of AIF-induced apoptosis was extensively investigated, whereas the mitochondrial function of AIF is poorly understood. A unique feature of AIF is the ability to form a tight, air-stable charge-transfer (CT) complex upon reaction with NADH and to undergo a conformational switch leading to dimerization, proposed to be important for its vital and lethal functions. Although some aspects of interaction of AIF with NAD⁺/H have been analyzed, its precise mechanism is not fully understood. We investigated how the oxidized and photoreduced wild-type and G307A and -E variants of murine AIF associate with NAD⁺/H and nicotinamide mononucleotide (NMN⁺/H) to determine the role of the adenylate moiety in the binding process. Our results indicate that (i) the adenylate moiety of NAD⁺/H is crucial for the association with AIF and for the subsequent structural reorganization of the complex, but not for protein dimerization, (ii) FAD reduction rather than binding of NAD⁺/H to AIF initiates conformational rearrangement, and (iii) alteration of the adenylate-binding site by the G307E (equivalent to a pathological G308E mutation in human AIF) or G307A replacements decrease the affinity and association rate of NAD⁺/H, which, in turn, perturbs CT complex formation and protein dimerization but has no influence on the conformational switch in the regulatory peptide

The Importance of the “Time Factor” for the Evaluation of Inhibition Mechanisms: The Case of Selected HDAC6 Inhibitors

Histone deacetylases (HDACs) participate with histone acetyltransferases in the modulation of the biological activity of a broad array of proteins, besides histones. Histone deacetylase 6 is unique among HDAC as it contains two catalytic domains, an N-terminal microtubule binding region and a C-terminal ubiquitin binding domain. Most of its known biological roles are related to its protein lysine deacetylase activity in the cytoplasm. The design of specific inhibitors is the focus of a large number of medicinal chemistry programs in the academy and industry because lowering HDAC6 activity has been demonstrated to be beneficial for the treatment of several diseases, including cancer, and neurological and immunological disorders. Here, we show how re-evaluation of the mechanism of action of selected HDAC6 inhibitors, by monitoring the time-dependence of the onset and relief of the inhibition, revealed instances of slow-binding/slow-release inhibition. The same approach, in conjunction with X-ray crystallography, in silico modeling and mass spectrometry, helped to propose a model of inhibition of HDAC6 by a novel difluoromethyloxadiazole-based compound that was found to be a slow-binding substrate analog of HDAC6, giving rise to a tightly bound, long-lived inhibitory derivative