Structure of the lipopolysaccharide O-antigen of endophytic Pseudomonas sp. strain L1.

The O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Pseudomonas sp. Strain L1, the endophytic bacteria of Lolium perenne (ryegrass) plants growing in soil in an industrial area in the Silesia region (Zabrze, Southern Poland). The high-molecular-weight O-PS fraction liberated from Pseudomonas sp. L1 lipopolysaccharide by mild acid hydrolysis was studied using chemical methods, MALDI-TOF mass spectrometry, and 1D and 2D NMR spectroscopy techniques. It was found that the O-specific polysaccharide was built of tetrasaccharide repeating units composed of d-FucpN, d-Fucp4N, and two d-QuipN residues. The following structure of the O-PS of Pseudomonas sp. Strain L1 was established: [Formula: see text].

Structure of the lipopolysaccharide O-antigen of Serratia spp. strains 10.1WK and 1XS plant endophytes isolated from O. biennis and L. corniculatus.

O-specific polysaccharides (O-PSs) isolated from lipopolysaccharides of Serratia spp., strains 10.1WK and 1XS, which are endophytic bacteria of Oenothera biennis (common evening-primrose) and Lotus corniculatus (bird's-foot trefoil), plants growing on a petroleum hydrocarbon polluted site in the Silesia region, were investigated. The high-molecular-weight O-PS fractions liberated from lipopolysaccharides by mild acid hydrolysis were studied using chemical methods, MALDI-TOF mass spectrometry, and a set of 1D and 2D NMR spectroscopy techniques. It was found that both O-specific polysaccharides were built of an identical trisaccharide repeating unit composed of d-Rhap and d-Manp residues. The following structure of the O-PSs of Serratia spp. strains 10.1WK and 1XS was established: →4)-α-d-Rhap-(1 â†’ 3)-ß-d-Manp-(1 â†’ 4)-ß-d-Rhap-(1→.

Lighting Conditions Influence the Dynamics of Protease Synthesis and Proteasomal Activity in the White Rot Fungus Cerrena unicolor.

Recent transcriptomic and biochemical studies have revealed that light influences the global gene expression profile and metabolism of the white-rot fungus Cerrena unicolor. Here, we aimed to reveal the involvement of proteases and ubiquitin-mediated proteolysis by the 26S proteasome in the response of this fungus to white, red, blue and green lighting conditions and darkness. The changes in the expression profile of C. unicolor genes putatively engaged in proteolysis were found to be unique and specific to the applied wavelength of light. It was also demonstrated that the activity of proteases in the culture fluid and mycelium measured using natural and synthetic substrates was regulated by light and was substrate-dependent. A clear influence of light on protein turnover and the qualitative and quantitative changes in the hydrolytic degradation of proteins catalyzed by various types of proteases was shown. The analysis of activity associated with the 26S proteasome showed a key role of ATP-dependent proteolysis in the initial stages of adaptation of fungal cells to the stress factors. It was suggested that the light-sensing pathways in C. unicolor are cross-linked with stress signaling and secretion of proteases presumably serving as regulatory molecules.

Effect of Ferulic Acid, a Phenolic Inducer of Fungal Laccase, on 26S Proteasome Activities In Vitro.

The 26S proteasome is an ATP-dependent protease complex (2.5 MDa) that degrades most cellular proteins in Eukaryotes, typically those modified by a polyubiquitin chain. The proteasome-mediated proteolysis regulates a variety of critical cellular processes such as transcriptional control, cell cycle, oncogenesis, apoptosis, protein quality control, and stress response. Previous studies conducted in our laboratory have shown that 26S proteasomes are involved in the regulation of ligninolytic enzymes (such as laccase) in white-rot fungi in response to nutrient starvation, cadmium exposure, and ER stress. Laccases are useful biocatalysts for a wide range of biotechnological applications. The goal of the current study was to determine the effect of ferulic acid (4-hydroxy-3-methoxycinnamic acid), a phenolic compound known to induce some ligninolytic enzymes, on proteasomes isolated from mycelia of the wood-decomposing basidiomycete Trametes versicolor. The peptidase activities of 26S proteasomes were assayed by measuring the hydrolysis of fluorogenic peptide substrates specific for each active site: Suc-LLVY-AMC, Z-GGR-AMC and Z-LLE-AMC for chymotrypsin-like, trypsin-like, and caspase-like site, respectively. Ferulic acid affected all peptidase activities of the 26S fungal proteasomes in a concentration-dependent manner. A possible inhibitory effect of ferulic acid on peptidase activities of the 26S human proteasomes was tested as well. Moreover, the ability of ferulic acid to inhibit (at concentrations known to induce laccase activity in white-rot fungi) the rate of 26S proteasome-catalyzed degradation of a model full-length protein substrate (ß-casein) was demonstrated by a fluorescamine assay and by a gel-electrophoretic analysis. Our findings provide new insights into the role of ferulic acid in lignin-degrading fungi. However, the detailed molecular mechanisms involved remain to be elucidated by future studies.