Evaluation of the role of unconventional prefoldin RPB5 interactor (URI1) in hepatitis B virus infection.

Hepatitis B virus (HBV) infection can cause liver disease and lead to hepatocellular carcinoma (HCC). To better understand the factors involved in viral infection and pathogenesis and to develop novel therapies, it is crucial to investigate virus-host interactions. HBV infection has been shown to increase the expression of the unconventional prefoldin RPB5 interactor (URI1), a cellular protein that promotes liver tumorigenesis and HCC metastasis.

Deciphering the allosteric regulation of mycobacterial inosine-5'-monophosphate dehydrogenase.

Allosteric regulation of inosine 5'-monophosphate dehydrogenase (IMPDH), an essential enzyme of purine metabolism, contributes to the homeostasis of adenine and guanine nucleotides. However, the precise molecular mechanism of IMPDH regulation in bacteria remains unclear. Using biochemical and cryo-EM approaches, we reveal the intricate molecular mechanism of the IMPDH allosteric regulation in mycobacteria.

Design, Synthesis, Biological Evaluation, and Crystallographic Study of Novel Purine Nucleoside Phosphorylase Inhibitors.

Purine nucleoside phosphorylase (PNP) is a well-known molecular target with potential therapeutic applications in the treatment of T-cell malignancies and/or bacterial/parasitic infections. Here, we report the design, development of synthetic methodology, and biological evaluation of a series of 30 novel PNP inhibitors based on acyclic nucleoside phosphonates bearing a 9-deazahypoxanthine nucleobase. The strongest inhibitors exhibited IC values as low as 19 nM (human PNP) and 4 nM ( () PNP) and highly selective cytotoxicity toward various T-lymphoblastic cell lines with CC values as low as 9 nM.

Biosynthesis of Fatty Acid Derivatives by Recombinant Containing MsexD2 and MsexD3 Desaturase Genes from .

One of the most interesting groups of fatty acid derivates is the group of conjugated fatty acids from which the most researched include: conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA), which are associated with countless health benefits. Sex pheromone mixtures of some insect species, including tobacco horn-worm (), are typical for the production of uncommon C16 long conjugated fatty acids with two and three conjugated double bonds, as opposed to C18 long CLA and CLNA. In this study, desaturases MsexD2 and MsexD3 were expressed in multiple strains of with different genotypes.

The structure of DarB in complex with Rel reveals nonribosomal activation of Rel stringent factors.

Rel stringent factors are bifunctional ribosome-associated enzymes that catalyze both synthesis and hydrolysis of the alarmones (p)ppGpp. Besides the allosteric control by starved ribosomes and (p)ppGpp, Rel is regulated by various protein factors depending on specific stress conditions, including the c-di-AMP-binding protein DarB. However, how these effector proteins control Rel remains unknown.

Understanding desaturation/hydroxylation activity of castor stearoyl Δ-Desaturase through rational mutagenesis.

A recently proposed reaction mechanism of soluble Δ desaturase (ΔD) allowed us to identify auxiliary residues His203, Asp101, Thr206 and Cys222 localized near the di-iron active site that are supposedly involved in the proton transfer (PT) to and from the active site. The PT, along with the electron transfer (ET), seems to be crucial for efficient desaturation. Thus, perturbing the major PT chains is expected to impair the native reaction and (potentially) amplify minor reaction channels, such as the substrate hydroxylation.

The mycobacterial guaB1 gene encodes a guanosine 5'-monophosphate reductase with a cystathionine-β-synthase domain.

Mycobacteria express enzymes from both the de novo and purine-salvage pathways. However, the regulation of these processes and the roles of individual metabolic enzymes have not been sufficiently detailed. Both Mycobacterium tuberculosis (Mtb) and Mycobacterium smegmatis (Msm) possess three guaB genes, but information is only available on guaB2, which encodes an essential inosine 5'-monophosphate dehydrogenase (IMPDH) involved in de novo purine biosynthesis.

Biogenesis of hepatitis B virus e antigen is driven by translocon-associated protein complex and regulated by conserved cysteine residues within its signal peptide sequence.

Hepatitis B virus uses e antigen (HBe), which is dispensable for virus infectivity, to modulate host immune responses and achieve viral persistence in human hepatocytes. The HBe precursor (p25) is directed to the endoplasmic reticulum (ER), where cleavage of the signal peptide (sp) gives rise to the first processing product, p22. P22 can be retro-translocated back to the cytosol or enter the secretory pathway and undergo a second cleavage event, resulting in secreted p17 (HBe).

Structural determinants for subnanomolar inhibition of the secreted aspartic protease Sapp1p from .

Pathogenic yeasts frequently cause infections in hospitals. Antifungal drugs lose effectiveness due to other species and resistance. New medications are thus required.

Crystal structures of inhibitor complexes of M-PMV protease with visible flap loops.

Mason-Pfizer monkey virus protease (PR) was crystallized in complex with two pepstatin-based inhibitors in P1 space group. In both crystal structures, the extended flap loops that lock the inhibitor/substrate over the active site, are visible in the electron density either completely or with only small gaps, providing the first observation of the conformation of the flap loops in dimeric complex form of this retropepsin. The H-bond network in the active site (with D26N mutation) differs from that reported for the P2 crystal structures and is similar to a rarely occurring system in HIV-1 PR.

Phosphofructokinases A and B from Display Different Catalytic Properties and Allosteric Regulation.

Tuberculosis (TB) remains one of the major health concerns worldwide. (Mtb), the causative agent of TB, can flexibly change its metabolic processes during different life stages. Regulation of key metabolic enzyme activities by intracellular conditions, allosteric inhibition or feedback control can effectively contribute to Mtb survival under different conditions.

Production of Long Chain Fatty Alcohols Found in Bumblebee Pheromones by .

Fatty alcohols (FA-OH) are aliphatic unbranched primary alcohols with a chain of four or more carbon atoms. Besides potential industrial applications, fatty alcohols have important biological functions as well. In nature, fatty alcohols are produced as a part of a mixture of pheromones in several insect species, such as moths, termites, bees, wasps, etc.

Toll-like receptor dual-acting agonists are potent inducers of PBMC-produced cytokines that inhibit hepatitis B virus production in primary human hepatocytes.

Recombinant interferon-α (IFN-α) treatment functionally cures chronic hepatitis B virus (HBV) infection in some individuals and suppresses virus replication in hepatocytes infected in vitro. We studied the antiviral effect of conditioned media (CM) from peripheral blood mononuclear cells (PBMCs) stimulated with agonists of Toll-like receptors (TLRs) 2, 7, 8 and 9. We found that CM from PBMCs stimulated with dual-acting TLR7/8 (R848) and TLR2/7 (CL413) agonists were more potent drivers of inhibition of HBe and HBs antigen secretion from HBV-infected primary human hepatocytes (PHH) than CM from PBMCs stimulated with single-acting TLR7 (CL264) or TLR9 (CpG-B) agonists.

Desaturase specificity is controlled by the physicochemical properties of a single amino acid residue in the substrate binding tunnel.

Membrane fatty acyl desaturases (mFAD) are ubiquitous enzymes in eukaryotes. They introduce double bonds into fatty acids (FAs), producing structurally diverse unsaturated FAs which serve as membrane lipid components or precursors of signaling molecules. The mechanisms controlling enzymatic specificity and selectivity of desaturation are, however, poorly understood.

Cellular Localization of Carbonic Anhydrase Nce103p in and .

Pathogenic yeasts and possess a ß-type carbonic anhydrase Nce103p, which is involved in CO hydration and signaling. lacking Nce103p cannot survive in low CO concentrations, e.g.

Hypoxanthine-Guanine Phosphoribosyltransferase Is Dispensable for Mycobacterium smegmatis Viability.

Purine metabolism plays a ubiquitous role in the physiology of and other mycobacteria. The purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is essential for growth ; however, its precise role in physiology is unclear. Membrane-permeable prodrugs of specifically designed HGPRT inhibitors arrest the growth of and represent potential new antituberculosis compounds.

Catabolism of 8-oxo-purines is mainly routed via the guanine to xanthine interconversion pathway in Mycobacterium smegmatis.

Metabolism of purine bases remains poorly understood in the pathogenic bacterium Mycobacterium tuberculosis and closely related, nonpathogenic Mycobacterium smegmatis (Msm). To gain insight into the purine metabolism in mycobacteria, we tested uptake of purine bases with a ΔpurF Msm mutant with an inactive purine de novo biosynthesis pathway and confirmed that hypoxanthine and guanine, but not xanthine, can serve as nucleotide precursors for recycling in the salvage pathway. Further, we focused on purine catabolism in wild-type (wt) Msm.

Comparison of a retroviral protease in monomeric and dimeric states.

Retroviral proteases (RPs) are of high interest owing to their crucial role in the maturation process of retroviral particles. RPs are obligatory homodimers, with a pepsin-like active site built around two aspartates (in DTG triads) that activate a water molecule, as the nucleophile, under two flap loops. Mason-Pfizer monkey virus (M-PMV) is unique among retroviruses as its protease is also stable in the monomeric form, as confirmed by an existing crystal structure of a 13 kDa variant of the protein (M-PMV PR) and its previous biochemical characterization.

Hepatitis B Virus X Protein Function Requires Zinc Binding.

The host structural maintenance of chromosomes 5/6 complex (Smc5/6) suppresses hepatitis B virus (HBV) transcription. HBV counters this restriction by expressing the X protein (HBx), which redirects the cellular DNA damage-binding protein 1 (DDB1)-containing E3 ubiquitin ligase to target Smc5/6 for degradation. However, the details of how HBx modulates the interaction between DDB1 and Smc5/6 remain to be determined.

Expansion of the fatty acyl reductase gene family shaped pheromone communication in Hymenoptera.

Fatty acyl reductases (FARs) are involved in the biosynthesis of fatty alcohols that serve a range of biological roles. Insects typically harbor numerous FAR gene family members. While some FARs are involved in pheromone biosynthesis, the biological significance of the large number of FARs in insect genomes remains unclear.

Decolorization and detoxification of textile wastewaters by recombinant and laccases.

Laccases are multi-copper oxidoreductases with broad biotechnological applications. Here, we report detailed biochemical characterization of purified recombinant laccases originating from (MtL) and (TtL). We identified optimal conditions for decolorization of commercial dyes and textile wastewater samples.

Allosteric regulation of pyruvate kinase from Mycobacterium tuberculosis by metabolites.

Mycobacterium tuberculosis (Mtb) causes both acute tuberculosis and latent, symptom-free infection that affects roughly one-third of the world's population. It is a globally important pathogen that poses multiple dangers. Mtb reprograms its metabolism in response to the host niche, and this adaptation contributes to its pathogenicity.

Crystal structure of carbonic anhydrase CaNce103p from the pathogenic yeast Candida albicans.

Background: The pathogenic yeast Candida albicans can proliferate in environments with different carbon dioxide concentrations thanks to the carbonic anhydrase CaNce103p, which accelerates spontaneous conversion of carbon dioxide to bicarbonate and vice versa. Without functional CaNce103p, C. albicans cannot survive in atmospheric air.

Efficient secretion of three fungal laccases from Saccharomyces cerevisiae and their potential for decolorization of textile industry effluent-A comparative study.

Laccases are enzymes with a broad range of biotechnological applications and have, for example, the ability to oxidize many xenobiotics including synthetic dyes. In order to obtain an efficient laccase for the decolorization of dyes which spoil wastewater from the textile industry, genes encoding three various laccase enzymes were expressed in Saccharomyces cerevisiae. The expression of laccases from ascomycete Myceliophthora thermophila (MtL), and two basidiomycetes Trametes versicolor (TvL) and Trametes trogii (TtL) was optimized via selection of plasmids, promoters, media composition, and cultivation conditions.