Tryptophan catabolism via kynurenine production in Streptomyces coelicolor: identification of three genes coding for the enzymes of tryptophan to anthranilate pathway

Most enzymes involved in tryptophan catabolism via kynurenine formation are highly conserved in Prokaryotes and Eukaryotes. In humans, alterations of this pathway have been related to different pathologies mainly involving the central nervous system. In Bacteria, tryptophan and some of its derivates are important antibiotic precursors. Tryptophan degradation via kynurenine formation involves two different pathways: the eukaryotic kynurenine pathway, also recently found in some bacteria, and the tryptophan-to-anthranilate pathway, which is widespread in microorganisms. The latter produces anthranilate using three enzymes also involved in the kynurenine pathway: tryptophan 2,3-dioxygenase (TDO), kynureninase (KYN), and kynurenine formamidase (KFA). In Streptomyces coelicolor, where it had not been demonstrated which genes code for these enzymes, tryptophan seems to be important for the calcium- dependent antibiotic (CDA) production. In this study, we describe three adjacent genes of S. coelicolor (SCO3644, SCO3645, and SCO3646), demonstrating their involvement in the tryptophan-to-anthranilate pathway: SCO3644 codes for a KFA, SCO3645 for a KYN and SCO3646 for a TDO. Therefore, these genes can be considered as homologous respectively to kynB, kynU, and kynA of other microorganisms and belong to a constitutive catabolic pathway in S. coelicolor, which expression increases during the stationary phase of a culture grown in the presence of tryptophan. Moreover, the S. coelicolor \u394kynU strain, in which SCO3645 gene is deleted, produces higher amounts of CDA compared to the wild-type strain. Overall, these results describe a pathway, which is used by S. coelicolor to catabolize tryptophan and that could be inactivated to increase antibiotic production

Lipids of human gastric mucosa: effect inflammatory infiltrates, Helicobacter pylori infection and non alcoholic cirrhosis. Chemical analysis of endoscopic biopsies in chronic atrophic gastritis.

Background/Aims: Gastric mucosa phospholipids play an important protective role against exogenous and endogenous toxic agents. Recently, we described a significant alteration of phospholipid profile in patients with chronic atrophic gastritis without Helicobacter pylori infection. The aim of the present study was to assess the phospholipid composition of gastric biopsy specimens in 41 subjects with chronic gastritis in relation to H. pylori infection (no. 26) and nonalcoholic cirrhosis (no. 18). Methods: Phospholipids were extracted from homogenate mucosal samples using Folch's method, purified, and separated by thin-layer chromatography, while bound fatty acids were analyzed by gas liquid chromatography. Results: The amounts of five gastric phospholipid classes, their rank order, and percent distribution of the principal ones (phosphatidylcholine [PC] 58%, phosphatidylethanolamine [PE] 26%, and phosphatidylinositol 11% vs. values of 49, 19, and 14, respectively, in the earlier study) were confirmed in chronic gastritis without H. pylori infection. H. pylori infection induced a dramatic reduction (about 30%) in the absolute amount of total phospholipids (24.2 μg/mg protein versus 35.1 of the H. pylori-negative group; P < 0.01), PC and PE being the most affected (-36% and -26%, respectively), while bound fatty acids remained unchanged. There was no difference in cirrhotic vs. noncirrhotic subjects. Conclusions: (1) The development of gastritis is characterized by an alteration of the lipid mucosal pattern that can change with the different etiologies, the most dramatic variations being observed in the presence of H. pylori infection; and (2) cirrhosis does not affect further the alteration in the phospholipid profile of the antral mucosa caused by chronic gastritis

Intratracheal administration of small interfering RNA targeting fas reduces lung ischemia-reperfusion injury

Objectives: Lung ischemia-reperfusion injury is the main cause of primary graft dysfunction after lung transplantation and results in increased morbidity and mortality. Fas-mediated apoptosis is one of the pathologic mechanisms involved in the development of ischemia-reperfusion injury. We hypothesized that the inhibition of Fas gene expression in lungs by intratracheal administration of small interfering RNA could reduce lung ischemia-reperfusion injury in an ex vivo model reproducing the procedural sequence of lung transplantation. Design: Prospective, randomized, controlled experimental study. Setting: University research laboratory. Subjects: C57/BL6 mice weighing 28-30 g. Interventions: Ischemia-reperfusion injury was induced in lungs isolated from mice, 48 hours after treatment with intratracheal small interfering RNA targeting Fas, control small interfering RNA, or vehicle. Isolated lungs were exposed to 6 hours of cold ischemia (4\ub0C), followed by 2 hours of warm (37\ub0C) reperfusion with a solution containing 10% of fresh whole blood and mechanical ventilation with constant low driving pressure. Measurements and Main Results: Fas gene expression was significantly silenced at the level of messenger RNA and protein after ischemia-reperfusion in lungs treated with small interfering RNA targeting Fas compared with lungs treated with control small interfering RNA or vehicle. Silencing of Fas gene expression resulted in reduced edema formation (bronchoalveolar lavage protein concentration and lung histology) and improvement in lung compliance. These effects were associated with a significant reduction of pulmonary cell apoptosis of lungs treated with small interfering RNA targeting Fas, which did not affect cytokine release and neutrophil infiltration. Conclusions: Fas expression silencing in the lung by small interfering RNA is effective against ischemia-reperfusion injury. This approach represents a potential innovative strategy of organ preservation before lung transplantation. \ua9 2016 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc