Heterologous expression of heterodimeric laccase from Pleurotus ostreatus in Kluyveromyces lactis

Among the laccases produced by the white-rot fungus Pleurotus ostreatus, there are two closely related atypical isoenzymes, POXA3a and POXA3b. These isoenzymes are endowed with quaternary structure, consisting of two subunits very different in size. The POXA3 large subunit is clearly homologous to other known laccases, while the small subunit does not show significant homology with any protein in data banks. To investigate on the singular structure of the POXA3 complex, a new system for recombinant expression of heterodimer proteins in the yeast Kluyveromyces lactis has been set up. A unique expression vector has been used and the cDNAs encoding the two subunits have been cloned under the control of the same bi-directionally acting promoter. Expression of the large subunit alone and co-expression of both subunits in the same host have been demonstrated and the properties of the recombinant proteins have been compared. Clones expressing the large subunit alone exhibited always notably lower activity than those expressing both subunits. In addition to the activity increase, the presence of the small subunit led to a significant increase of laccase stability. Therefore, a role of the small subunit in POXA3 stabilisation is suggested.     

Diketopiperazines Produced by the Halophilic Archaeon, <Emphasis Type="Italic">Haloterrigena hispanica</Emphasis>, Activate AHL Bioreporters

The generic term “quorum sensing” has been adopted to describe the bacterial cell-to-cell communication mechanism which coordinates gene expression when the population has reached a high cell density. Quorum sensing depends on the synthesis of small molecules that diffuse in and out of bacterial cells. There are few reports about this mechanism in Archaea. We report the isolation and chemical characterization of small molecules belonging to class of diketopiperazines (DKPs) in Haloterrigena hispanica, an extremely halophilic archaeon. One of the DKPs isolated, the compound cyclo-(l-prolyl–l-valine) activated N-acyl homoserine lactone (AHL) bioreporters, indicating that Archaea may have the ability to interact with AHL-producing bacteria within mixed communities.     

TatAc, the third TatA subunit of Bacillus subtilis, can form active twin-arginine translocases with the TatCd and TatCy subunits

Two independent twin-arginine translocases (Tat) for protein secretion were previously identified in the Gram-positive bacterium Bacillus subtilis. These consist of the TatAd-TatCd and TatAy-TatCy subunits. The function of a third TatA subunit named TatAc was unknown. Here, we show that TatAc can form active protein translocases with TatCd and TatCy.     

Olive orchard microbiome: characterisation of bacterial communities in soil-plant compartments and their comparison between sustainable and conventional soil management systems

ABSTRACT

Background

Beneficial bacteria-plant interactions play an important role in agriculture, positively affecting plant status and improving product quality. Bacterial endophytes contribute to host plant protection and survival.     

Lesional Accumulation of CD163-Expressing Cells in the Gut of Patients with Inflammatory Bowel Disease

Monocytes/macrophages displaying different markers of activation/differentiation infiltrate the inflamed gut of patients with inflammatory bowel diseases (IBD), but the role that each monocyte/macrophage subpopulation plays in the pathogenesis of IBD is not fully understood. The hemoglobin scavenger receptor CD163, a specific marker of monocytes/macrophages, has been associated with either anti-inflammatory or inflammatory functions of macrophages in several pathologies. In this study we examined the tissue distribution and function of CD163-expressing monocytes/macrophages in IBD. CD163 RNA and protein expression was more pronounced in IBD in comparison to normal controls, with no significant difference between Crohn''s disease and Ulcerative colitis. In IBD, over-expression of CD163 was restricted to areas with active inflammation and not influenced by current therapy. Immunohistochemical analysis confirmed the accumulation of CD163-expressing cells in IBD, mostly around and inside blood vessels, thus suggesting that these cells are partly recruited from the systemic circulation. Indeed, FACS analysis of circulating mononuclear cells showed that the fractions of CD163-positive monocytes were increased in IBD patients as compared to controls. Functionally, interleukin-6 up-regulated CD163 expression in lamina propria mononuclear cells and mucosal explants of normal subjects. In IBD blood and mucosal cell cultures, cross-linking of CD163 with a specific monoclonal anti-CD163 antibody enhanced tumor necrosis factor-α synthesis. These findings indicate that IBD mucosa is abundantly infiltrated with CD163-positive cells, which could contribute to amplify the inflammatory cytokine response.     

Degradation of the Twin-Arginine Translocation Substrate YwbN by Extracytoplasmic Proteases of Bacillus subtilis

Bacterial twin-arginine translocases can export fully folded proteins from the cytoplasm. Such proteins are usually resistant to proteolysis. Here we show that multiple extracellular proteases degrade the B. subtilis Tat substrate YwbN. This suggests either that secreted YwbN is not fully folded or that folded YwbN exposes protease cleavage sites.     

Proposal for an integrated approach to microbial environmental monitoring in cultural heritage: experience at the Correggio exhibition in Parma

Microbial environmental monitoring represents one of the most useful methods to assess potential risks related to the integrity of cultural heritage and people’s health. The monitoring plan described in the present work is based on standardized techniques for measuring microbial air and surface contamination. Air contamination is assessed through both active and passive samplings, measuring the concentration of microbes in air (in colony forming units per cubic metre, CFU/m³) and the rate at which microorganisms settle on surfaces (expressed by the Index of Microbial Air Contamination, IMA, CFU/dm²/h). For surface contamination, two parameters are measured using nitrocellulose membranes: the Microbial Buildup (MB, the total number of microorganisms accumulated on a surface in an unknown period of time prior to the sampling) and the Hourly Microbial Fallout (HMF, the number of microorganisms that settle on a specific surface during 1 h). The monitoring plan was implemented at the Pilotta Palace in Parma, Italy, during the Correggio exhibition in 2009. Samplings were taken before and during opening times. Some microbial contamination was already detected before the arrival of visitors: air contamination mean values of 99.1 CFU/m³ and 5.2 CFU/dm²/h were recorded, while MB and HMF mean values for surfaces were 92 and 7 CFU/dm², respectively. A significant increase was recorded in air contamination during opening times, with mean values of 323.7 CFU/m³ and 19.4 CFU/dm²/h; surface contamination values increased as well. This monitoring plan represents a contribution towards the definition of a much needed standardized methodology.     

Cercosporoid hyphomycetes on malpighiaceous hosts from the Brazilian Cerrado: New Passalora and Pseudocercospora species on hosts of the genus Banisteriopsis

Six new species of cercosporoid fungi were found on leaves of Banisteriopsis species from the Cerrado: Passalora chapadensis, P. delamonicae, and P. guimaranhensis on Banisteriopsis megaphylla, B. pubipetala, and B. megaphylla, respectively, and Pseudocercospora banisteriopsis-megaphyllae, P. matogrossoensis, and P. uwebrauniana on Banisteriopsis megaphylla, B. membranifolia, and B. stellaris, respectively.     

Calcium-Dependent Networks in Dopamine–Glutamate Interaction: The Role of Postsynaptic Scaffolding Proteins

Dopamine and glutamate systems are both involved in cognitive, behavioral, and motor processes. Dysfunction of dopamine–glutamate interplay has been suggested in several psychotic diseases, above all in schizophrenia, for which there exists a need for novel medications. Intracellular calcium-dependent transduction pathways are key determinants of dopamine–glutamate interactions, which take place mainly, albeit not exclusively, in the postsynaptic density (PSD), a highly specialized postsynaptic ultrastructure. Stimulation of dopamine and glutamate receptors modulates the gene expression and the function of specific PSD proteins, the “scaffolding” proteins (Homer, Shank, and PSD95), belonging to a complex Ca²⁺-regulated network that integrates and converges dopamine and glutamate signaling to appropriate nuclear targets. Dysfunction of scaffolding proteins leads to severe impairment of Ca²⁺-dependent signaling, which may underlie the dopamine–glutamate aberrations putatively implicated in the pathogenesis of psychotic disorders. Antipsychotic therapy has been demonstrated to directly and indirectly affect the neuronal Ca²⁺-dependent pathways through the modulation of PSD scaffolding proteins, such as Homer, therefore influencing both dopaminergic and glutamatergic functions and enforcing Ca²⁺-mediated long-term synaptic changes. In this review, we will discuss the role of PSD scaffolding proteins in routing Ca²⁺-dependent signals to the nucleus. In particular, we will address the implication of PSD scaffolding proteins in the intracellular connections between dopamine and glutamate pathways, which involve both Ca²⁺-dependent and Ca²⁺-independent mechanisms. Finally, we will discuss how new strategies for the treatment of psychosis aim at developing antipsychotics that may impact both glutamate and dopamine signaling, and what should be the possible role of PSD scaffolding proteins.