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The bacterial DNA gyrase complex (GyrA/GyrB) plays a crucial role during DNA replication and serves as a target for multiple antibiotics, including the fluoroquinolones. Despite it being a valuable antibiotics target, resistance emergence by pathogens including Pseudomonas aeruginosa are proving problematic. Here, we describe Igy, a peptide inhibitor of gyrase, encoded by Pseudomonas bacteriophage LUZ24 and other members of the Bruynoghevirus genus. Igy (5.6 kDa) inhibits in vitro gyrase activity and interacts with the P. aeruginosa GyrB subunit, possibly by DNA mimicry, as indicated by a de novo model of the peptide and mutagenesis. In vivo, overproduction of Igy blocks DNA replication and leads to cell death also in fluoroquinolone-resistant bacterial isolates. These data highlight the potential of discovering phage-inspired leads for antibiotics development, supported by co-evolution, as Igy may serve as a scaffold for small molecule mimicry to target the DNA gyrase complex, without cross-resistance to existing molecules. "Fonds Wetenschappelijk Onderzoek'' (FWO) [G.0323.09]; KULeuven project GOA "Phage Biosystems.''

Background Several clinical and experimental studies have demonstrated that advanced glycation end products (AGEs) are associated with adverse cardiac outcome. Growing evidence shows that high molecular weight AGEs (HMW-AGEs) might be as important as the characterized low molecular weight AGEs. To date, the role of HMW-AGEs in the pathogenesis of cardiac remodeling remains unknown. In this study, we investigated whether HMW-AGEs are involved in cardiac dysfunction. Methods Healthy rats were daily ip injected with 20mg/kg BSA-derived HMW-AGEs or, as a control, unmodified BSA, during 6weeks. Cardiac function was assessed with echocardiography. Plasma levels of glucose, AGEs and soluble RAGE (sRAGE) were measured. AGEs, RAGE and lysyl oxidase (LOX) expression were determined by western blot. Results After 6weeks, animals displayed a sustained increase in circulating total AGEs without hyperglycemia. HMW-AGEs injections induced cardiac dysfunction characterized by wall hypertrophy, increased heart sphericity, reduced strain and strain rate with preserved ejection fraction. Plasma sRAGE levels were significantly higher compared to control and correlated significantly with decreased strain. RAGE expression, TNF-α and IL-6 remained unchanged. Finally, HMW-AGEs induced prominent cardiac fibrosis associated with an increased LOX expression. Conclusion Our data demonstrate that rather than via a specific activation of RAGE, the deleterious effects of HMW-AGEs are likely mediated via an increased collagen cross-linking responsible for the observed cardiac stiffness. Additionally, we show that in the setting of elevated HMW-AGEs, increased sRAGE levels are markers of altered cardiac function.

Erwinia amylovora is a Gram-negative plant pathogen that causes fire blight. This disease affects most members of the Rosaceae family including apple and pear. Here, an infection model is introduced to study proteomic changes in a highly virulent E. amylovora strain upon interaction with its host as compared to a lower virulent strain. For this purpose separate shoots of apple rootstocks were wound-infected and when infection became systemic, bacterial cells were isolated and processed for analysis in a proteomics platform combining 2-D fluorescence difference gel electrophoresis and mass spectrometry. Comparing the proteome of the isolates, significant abundance changes were observed in proteins involved in sorbitol metabolism, amylovoran production as well as in protection against plant defense mechanisms. Furthermore several proteins associated with virulence were more abundant in the higher virulent strain. Changes at the proteome level showed good accordance at the transcript level, as was verified by RT-qPCR. In conclusion, this infection model may be a valuable tool to unravel the complexity of plant-pathogen interactions and to gain insight in the molecular mechanisms associated with virulence of E. amylovora, paving the way for the development of plant-protective interventions against this detrimental disease. Significance During this research a first time investigation was performed on the proteome of E. amylovora, grown inside a susceptible host plant. This bacterium is the causal agent of fire blight, which can affect most members of the Rosaceae family including apple and pear. To do so, an artificial infection model on shoots of apple rootstocks was optimized and employed. When infection was systemic, bacterial cells were extracted from the plant tissue followed by extraction of the proteins from the bacteria. Further processing of the proteins was done by using a 2-D fluorescence difference gel electrophoresis analysis followed by mass spectrometry. By the use of two strains differing in their virulent ability, we were able to draw conclusions concerning virulence and behavior of different strains inside the host. This research provides a model to investigate plant-pathogen interactions and more importantly, we identified possible new targets for the development of novel control methods against this devastating disease.

Two-dimensional electrophoresis (2-DE) coupled to a robust statistical approach comprising univariate and multivariate statistics and LC–ESI-MS/MS protein identification was used to improve the understanding of the physiology of pears submitted to four different controlled atmosphere (CA) conditions. Optimal commercial CA conditions (2.5% O2, 0.7% CO2, with pre-cooling and fruit from the optimal harvest date), browning-inducing CA conditions (1% O2, 10% CO2, using no pre-cooling and fruit from a late harvest) and two intermediate CA conditions (2.5% O2, 10% CO2 and 15% O2, 0.6% CO2, both including pre-cooling and fruit from the optimal harvest date) were evaluated. The combination of oxygen and carbon dioxide concentrations, pre-cooling period and harvest time plays a key role in core breakdown presumably in the protein levels during controlled atmosphere storage of pears. Our results show that impaired respiration is highly related to protein synthesis alterations, and activation of defense mechanisms. Triosephosphate isomerase, a key enzyme of the energy metabolism was up-regulated under browning-inducing conditions in an attempt to use alternative more efficient anaplerotic pathways to cope with the applied stresses. The changes in the accumulation of proteins related to ethylene biosynthesis (ACC oxidase) and allergens (major allergen Pyrc 1) were highly dependent on the oxygen and carbon dioxide concentrations. ACC oxidase and the major allergen Pyrc 1 were clearly down-regulated under low oxygen or high carbon dioxide concentrations. Their involvement in metabolic disturbances cannot be discarded.

One of the newly developed imaging mass spectrometry (IMS) technologies utilizes matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to map proteins in thin tissue sections. In this study, we evaluated the power of MALDI IMS as we developed it in our (Bruker) MALDI TOF (Reflex IV) and TOF-TOF (Ultraflex II) systems to study myelin patterns in the mouse central nervous system under normal and pathological conditions. MALDI IMS was applied to assess myelin basic protein (MBP) isoform-specific profiles in different regions throughout the mouse brain. The distribution of ions of m / z 14,144 and 18,447 displayed a striking resemblance with white matter histology and were identified as MBP isoform 8 and 5, respectively. In addition, we demonstrated a significant reduction of the MBP-8 peak intensity upon MALDI IMS analysis of focal ethidium bromide-induced demyelinated brain areas. Our MS images were validated by immunohistochemistry using MBP antibodies. This study underscores the potential of MALDI IMS to study the contribution of MBP to demyelinating diseases.

Seven metabolites of 4-chlorotestosterone acetate were identified in urine of cattle that received a single injection of the drug. The steroids were isolated by means of a series of clean-up steps carried out before and after enzymatic hydrolysis. The obtained extract was fractionated by high-performance liquid chromatography and each fraction was examined both by high-performance thin-layer chromatography and by capillary gas chromatography—mass spectrometry of the m -ethoxime—trimethylsilyl derivatives. The metabolites were tentatively identified by studying the mass spectra of selected peaks not found in blank samples. The structures of two metabolites, viz. 4-chloroandrost-4-ene-3,17-dione and 4-chloroandrost-4-ene-3α,17β-diol were confirmed by chemical synthesis. The synthesized metabolites and 4-chloro-17α-testosterone, a third metabolite which was identified tentatively, were located on the thin-layer chromatograms obtained. This study led to the conclusion that the illegal use of 4-chlorotestosterone acetate can be detected by identifying one or more of its metabolites in urine.