From the grapevine to the glass: A wine metabolomics tale by FT-ICR-MS

Wine is one of the most consumed beverages around the world. Its unique characteristics arise from numerous processes, from the selection of grapevine varieties and grapes, the effect of the terroir and geographical origin, through the biochemical process of fermentation by microorganisms, until its aging. All molecules found in wine define its chemical fingerprint and can be used to tell the story of its origin, production, authenticity and quality. Wine's chemical composition can be characterized using an untargeted metabolomics approach based on extreme resolution mass spectrometry. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is currently the most powerful analytical technique to analyse such complex sample, providing the most comprehensive analysis of the chemical fingerprint of wine.

Mapping the lipidome in mitochondria-associated membranes (MAMs) in an in vitro model of Alzheimer's disease

The disruption of mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) plays a relevant role in Alzheimer's disease (AD). MAMs have been implicated in neuronal dysfunction and death since it is associated with impairment of functions regulated in this subcellular domain, including lipid synthesis and trafficking, mitochondria dysfunction, ER stress-induced unfolded protein response (UPR), apoptosis, and inflammation. Since MAMs play an important role in lipid metabolism, in this study we characterized and investigated the lipidome alterations at MAMs in comparison with other subcellular fractions, namely microsomes and mitochondria, using an in vitro model of AD, namely the mouse neuroblastoma cell line (N2A) over-expressing the APP familial Swedish mutation (APPswe) and the respective control (WT) cells. Phospholipids (PLs) and fatty acids (FAs) were isolated from the different subcellular fractions and analyzed by HILIC-LC-MS/MS and GC-MS, respectively. In this in vitro AD model, we observed a down-regulation in relative abundance of some phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and lysophosphatidylethanolamine (LPE) species with PUFA and few PC with saturated and long-chain FA. We also found an up-regulation of CL, and antioxidant alkyl acyl PL. Moreover, multivariate analysis indicated that each organelle has a specific lipid profile adaptation in N2A APPswe cells. In the FAs profile, we found an up-regulation of C16:0 in all subcellular fractions, a decrease of C18:0 levels in total fraction (TF) and microsomes fraction, and a down-regulation of 9-C18:1 was also found in mitochondria fraction in the AD model. Together, these results suggest that the over-expression of the familial APP Swedish mutation affects lipid homeostasis in MAMs and other subcellular fractions and supports the important role of lipids in AD physiopathology.

Burst Phase Analysis of the Aggregation Prone α-synuclein Amyloid Protein

While some studies inferred that valid information can be retrieved for the refolding of proteins and consequent identification of folding intermediates in the stopped-flow spectrometry collapse phase, other studies report that these burst phase folding intermediates can be questioned, implying a solvent-dependent modification of the still unfolded polypeptide chain. We therefore decided to investigate the burst phase occurring for the α-synuclein (Syn) amyloid protein by stopped-flow spectrometry. Solvent-dependent modification effects indeed occurred for the Nα-acetyl-L-tyrosinamide (NAYA) parent small compound and for the folded monomeric ubiquitin protein. More complex was the burst phase analysis of the disordered Syn amyloid protein. While this amyloid protein was determined to be aggregated at pH 7 and pH 2, in particular, this protein at pH 3 appears to be in a monomeric state in the burst phase analysis performed. In addition, the protein at pH 3 appears to suffer a hydrophobic collapse with the formation of a possible folded intermediate. This folded intermediate seems to result from a fast contraction of the disordered amyloid polypeptide chain, which is proceeded by an expansion of the protein, due to the occurrence of solvent-dependent modification effects in a milliseconds time scale of the burst phase. Generally, it can be argued that both literature criteria of solvent-dependent modifications of the disordered Syn amyloid protein and of the formation of its possible folded intermediate are very likely to occur in the burst phase.

Initial Effect of Temperature Rise on α-Synuclein Aggregation - Entropic Forces Drive the Exposure of Protein Hydrophobic Groups Probed by Fluorescence Spectroscopy

The aberrant formation of α-synuclein (Syn) aggregates, varying in size, structure and morphology, has been linked to the development of Parkinson's disease. In the early stages of Syn aggregation, large protein amyloid aggregates with sizes > 100 nm in hydrodynamic radius have been noticed. These low overall abundant large Syn aggregates are notoriously difficult to study by conventional biophysical methods. Due to the growing importance of studying the early stages of Syn aggregation, we developed a strategy to achieve this purpose, which is the study of the initial effect of the Syn protein aqueous solutions temperature rise. Therefore, the increase of the Syn aqueous solutions entropy by the initial effect of the temperature rise led to the exposure of the protein hydrophobic tyrosyl groups by not interfering with this amyloid protein aggregation. As an attempt to interpret the degree of the referred protein tyrosyl groups exposure, the classic rotameric conformations of the Nα-acetyl-L-tyrosinamide (NAYA) parent compound were used. For both NAYA and Syn, it was determined that the classic rotameric conformations involving the tyrosyl groups indeed accounted for their exposure under steady-state conditions of fluorescence, for lowest molecular species concentrations investigated at least. In this situation, Syn aggregation was observed. For the higher NAYA and Syn concentrations studied, the referred classic rotameric conformation were insufficient in such referred steady-state conditions and, for Syn, in particular, fluorescence anisotropy measurements revealed that less protein aggregation occurs along with its delay. Overall, the developed strategy by focusing on the initial effect of the temperature rise of Syn aqueous solutions in lower concentrations is suitable for informing us about the degree of this protein aggregation in solution.

Monocarbonyl Analogs of Curcumin with Potential to Treat Colorectal Cancer

Curcumin has a plethora of biological properties, making this compound potentially effective in the treatment of several diseases, including cancer. However, curcumin clinical use is compromised by its poor pharmacokinetics, being crucial to find novel analogs with better pharmacokinetic and pharmacological properties. Here, we aimed to evaluate the stability, bioavailability and pharmacokinetic profiles of monocarbonyl analogs of curcumin. A small library of monocarbonyl analogs of curcumin 1a-q was synthesized. Lipophilicity and stability in physiological conditions were both assessed by HPLC-UV, while two different methods assessed the electrophilic character of each compound monitored by NMR and by UV-spectroscopy. The potential therapeutic effect of the analogs 1a-q was evaluated in human colon carcinoma cells and toxicity in immortalized hepatocytes. Our results showed that the curcumin analog 1e is a promising agent against colorectal cancer, with improved stability and efficacy/safety profile.

On the Occurrence and Multimerization of Two-Polypeptide Phage Endolysins Encoded in Single Genes

Bacteriophages (phages) and other viruses are extremely efficient in packing their genetic information, with several described cases of overlapping genes encoded in different open reading frames (ORFs). While less frequently reported, specific cases exist in which two overlapping ORFs are in frame and share the stop codon. Here, we studied the occurrence of this genetic arrangement in endolysins, the phage enzymes that cut the bacterial cell wall peptidoglycan to release the virion progeny. After screening over 3,000 endolysin sequences of phages infecting Gram-positive bacteria, we found evidence that this coding strategy is frequent in endolysin genes. Our bioinformatics predictions were experimentally validated by demonstrating that two polypeptides are indeed produced from these genes. Additionally, we show that in some cases the two polypeptides need to interact and multimerize to generate the active endolysin. By studying in detail one selected example, we uncovered a heteromeric endolysin with a 1:5 subunit stoichiometry that has never been described before. Hence, we conclude that the occurrence of endolysin genes encoding two polypeptide isoforms by in-frame overlapping ORFs, as well as their organization as enzymatic complexes, appears more common than previously thought, therefore challenging the established view of endolysins being mostly formed by single, monomeric polypeptide chains. IMPORTANCE Bacteriophages use endolysins to cleave the host bacteria cell wall, a crucial event underlying cell lysis for virion progeny release. These bacteriolytic enzymes are generally thought to work as single, monomeric polypeptides, but a few examples have been described in which a single gene produces two endolysin isoforms. These are encoded by two in-frame overlapping ORFs, with a shorter ORF being defined by an internal translation start site. This work shows evidence that this endolysin coding strategy is frequent in phages infecting Gram-positive bacteria, and not just an eccentricity of a few phages. In one example studied in detail, we show that the two isoforms are inactive until they assemble to generate a multimeric active endolysin, with a 1:5 subunit stoichiometry never described before. This study challenges the established view of endolysins, with possible implications in their current exploration and design as alternative antibacterials.