RNA-binding proteins in cancer drug discovery.

RNA-binding proteins (RBPs) are crucial players in tumorigenesis and, hence, promising targets in cancer drug discovery. However, they are largely regarded as 'undruggable', because of the often noncatalytic and complex interactions between protein and RNA, which limit the discovery of specific inhibitors. Nonetheless, over the past 10 years, drug discovery efforts have uncovered RBP inhibitors with clinical relevance, highlighting the disruption of RNA-protein networks as a promising avenue for cancer therapeutics.

Unveiling Druggable Pockets by Site-Specific Protein Modification: Beyond Antibody-Drug Conjugates.

Site-specific modification approaches have been extensively employed in the development of protein-based technologies. In this field, stability and activity integrity are the envisioned features of chemically modified proteins. These methods are especially used in the design of antibody-drug conjugates (ADCs).

The oncofetal RNA-binding protein IGF2BP1 is a druggable, post-transcriptional super-enhancer of E2F-driven gene expression in cancer.

The IGF2 mRNA-binding protein 1 (IGF2BP1) is a non-catalytic post-transcriptional enhancer of tumor growth upregulated and associated with adverse prognosis in solid cancers. However, conserved effector pathway(s) and the feasibility of targeting IGF2BP1 in cancer remained elusive. We reveal that IGF2BP1 is a post-transcriptional enhancer of the E2F-driven hallmark in solid cancers.

Enhancement of the Anti-Aggregation Activity of a Molecular Chaperone Using a Rationally Designed Post-Translational Modification.

Protein behavior is closely regulated by a plethora of post-translational modifications (PTMs). It is therefore desirable to develop approaches to design rational PTMs to modulate specific protein functions. Here, we report one such method, and we illustrate its successful implementation by potentiating the anti-aggregation activity of a molecular chaperone.

Posttranslational Chemical Mutagenesis: To Reveal the Role of Noncatalytic Cysteine Residues in Pathogenic Bacterial Phosphatases.

The field of chemical site-selective modification of proteins has progressed extensively in recent decades to enable protein functionalization for imaging, drug delivery, and functional studies. In this Perspective, we provide detailed insight into an alternative use of site-selective protein chemistry to probe the role(s) of unpaired Cys residues in the structure and function of disease relevant proteins. Phosphatases are important players in the successful infection of pathogenic bacteria, which represent a significant health burden, particularly in multi-drug-resistant strains.

Chemo- and Regioselective Lysine Modification on Native Proteins.

Site-selective chemical conjugation of synthetic molecules to proteins expands their functional and therapeutic capacity. Current protein modification methods, based on synthetic and biochemical technologies, can achieve site selectivity, but these techniques often require extensive sequence engineering or are restricted to the N- or C-terminus. Here we show the computer-assisted design of sulfonyl acrylate reagents for the modification of a single lysine residue on native protein sequences.

A Water-Bridged Cysteine-Cysteine Redox Regulation Mechanism in Bacterial Protein Tyrosine Phosphatases.

The emergence of multidrug-resistant () strains highlights the need to develop more efficacious and potent drugs. However, this goal is dependent on a comprehensive understanding of virulence protein effectors at the molecular level. Here, we used a post-expression cysteine (Cys)-to-dehydrolanine (Dha) chemical editing strategy to identify a water-mediated motif that modulates accessibility of the protein tyrosine phosphatase A (PtpA) catalytic pocket.

Site-selective installation of BASHY fluorescent dyes to Annexin V for targeted detection of apoptotic cells.

Fluorophores are indispensable for imaging biological processes. We report the design and synthesis of azide-tagged boronic acid salicylidenehydrazone (BASHY) dyes and their use for site-selective labelling of Annexin V. The Annexin V-BASHY conjugate maintained function and fluorescence as demonstrated by the targeted detection of apoptotic cells.

Oxidation and Tyrosine Nitration Induce Structural Changes and Inhibits Plasmodium falciparum Falcipain-2 Activity In Vitro.

Falcipain-2 (FP2) is an important hemoglobinase from the malaria parasite Plasmodium falciparum and a suitable target for the development of an antimalarial chemotherapy. Many reports have indicated that radical nitrogen species (RNS) including nitric oxide (NO) are inhibitors of P. falciparum growth and promoters of recovery from malaria symptoms.

Synthetic compounds from an in house library as inhibitors of falcipain-2 from Plasmodium falciparum.

Falcipain-2 (FP-2) is a key cysteine protease from the malaria parasite Plasmodium falciparum. Many previous studies have identified FP-2 inhibitors; however, none has yet met the criteria for an antimalarial drug candidate. In this work, we assayed an in-house library of non-peptidic organic compounds, including (E)-chalcones, (E)-N'-benzylidene-benzohydrazides and alkyl-esters of gallic acid, and assessed the activity toward FP-2 and their mechanisms of inhibition.

Protein S-nitrosylation: specificity and identification strategies in plants.

The role of nitric oxide (NO) as a major regulator of plant physiological functions has become increasingly evident. To further improve our understanding of its role, within the last few years plant biologists have begun to embrace the exciting opportunity of investigating protein S-nitrosylation, a major reversible NO-dependent post-translational modification (PTM) targeting specific Cys residues and widely studied in animals. Thanks to the development of dedicated proteomic approaches, in particular the use of the biotin switch technique (BST) combined with mass spectrometry, hundreds of plant protein candidates for S-nitrosylation have been identified.

Nitric oxide inhibits the ATPase activity of the chaperone-like AAA+ ATPase CDC48, a target for S-nitrosylation in cryptogein signalling in tobacco cells.

NO has important physiological functions in plants, including the adaptative response to pathogen attack. We previously demonstrated that cryptogein, an elicitor of defence reaction produced by the oomycete Phytophthora cryptogea, triggers NO synthesis in tobacco. To decipher the role of NO in tobacco cells elicited by cryptogein, in the present study we performed a proteomic approach in order to identify proteins undergoing S-nitrosylation.

Proteomic analysis of four Brazilian MON810 maize varieties and their four non-genetically-modified isogenic varieties.

Profiling techniques have been suggested as a nontargeted approach to detect unintended effects in genetically modified (GM) plants. Seedlings from eight Brazilian maize varieties, four MON810 GM varieties and four non-GM isogenic varieties, were grown under controlled environmental conditions. Physiological parameters (aerial part weight, main leaf length, and chlorophyll and total protein contents) were compared, and some differences were observed.

Structural stability of Staphylococcus xylosus lipase is modulated by Zn(2+) ions.

Lipases are well-known enzymes extensively used in industrial biotransformation processes. Besides, their structural and catalytic characteristics have attracted increasing attention of several industries in the last years. In this work, we used biophysical and molecular modeling tools to assess structural properties of Staphylococcus xylosus lipase (SXL).

Biochemical and structural characterization of two site-directed mutants of Staphylococcus xylosus lipase.

Staphylococcus xylosus AF208229 lipase was expressed in E. coli containing an histidine-tag (WT-Val). In the present work, in order to check the importance of the residue 309 in the specific activity, the amino acid side chain residue valine 309 was substituted by aspartate or lysine through site-directed mutagenesis.

Cloning, expression, purification, and characterization of a novel esterase from Lactobacillus plantarum.

Lactobacillus plantarum is an important lactic acid bacterium, usually found as natural inhabitant of food, such as fermented vegetables and meat products. However, little information about lactic acid bacteria, especially concerning L. plantarum, as a source of useful enzymes has been reported.

Heterologous Expression and Purification of a Heat-Tolerant Staphylococcus xylosus Lipase.

Staphylococcus xylosus is a microorganism involved in fermentation of meat products and also a natural producer of extracellular lipases. The aim of the present work was to clone and express in E. coli a lipase from S.

Evaluation of the toxic and genotoxic potential of landfill leachates using bioassays.

Landfill leachates are liquid effluents with elevated concentrations of chemical compounds that can cause serious environmental pollution. In the south of the state of Santa Catarina, Brazil, a sanitary landfill was installed that employs a system of anaerobic/facultative lagoons for the treatment of its leachate. The present work examined the toxic and genotoxic potential of untreated and treated landfill leachates using bioassays.

A transthyretin-related protein is functionally expressed in Herbaspirillum seropedicae.

Transthyretin-related proteins (TRPs) constitute a family of proteins structurally related to transthyretin (TTR) and are found in a large range of bacterial, fungal, plant, invertebrate, and vertebrate species. However, it was recently recognized that both prokaryotic and eukaryotic members of this family are not functionally related to transthyretins. TRPs are in fact involved in the purine catabolic pathway and function as hydroxyisourate hydrolases.