Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.184 (LasR)
 897 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, we identified a pyruvate fermentation pathway in Pseudomonas aeruginosa sustaining anaerobic survival in the absence of alternative anaerobic respiratory and fermentative energy generation systems (M. Eschbach, K. Schreiber, K. Trunk, J. Buer, D. Jahn, and M. Schobert, J. Bacteriol. 186:4596-4604, 2004). Anaerobic long-term survival of P. aeruginosa might be essential for survival in deeper layers of a biofilm and the persistent infection of anaerobic mucus plaques in the cystic fibrosis lung. Proteome analysis of P. aeruginosa cells during a 7-day period of pyruvate fermentation revealed the induced synthesis of three enzymes involved in arginine fermentation, ArcA, ArcB, and ArcC, and the outer membrane protein OprL. Moreover, formation of two proteins of unknown function, PA3309 and PA4352, increased by factors of 72- and 22-fold, respectively. Both belong to the group of universal stress proteins (Usp). Long-term survival of a PA3309 knockout mutant by pyruvate fermentation was found drastically reduced. The oxygen-sensing regulator Anr controls expression of the PPA3309-lacZ reporter gene fusion after a shift to anaerobic conditions and further pyruvate fermentation. PA3309 expression was also found induced during the anaerobic and aerobic stationary phases. This aerobic stationary-phase induction is independent of the regulatory proteins Anr, RpoS, RelA, GacA, RhlR, and LasR, indicating a currently unknown mechanism of stationary-phase-dependent gene activation. PA3309 promoter activity was detected in the deeper layers of a P. aeruginosa biofilm using a PPA3309-gfp (green fluorescent protein gene) fusion and confocal laser-scanning microscopy. This is the first description of an Anr-dependent, anaerobically induced, and functional Usp-like protein in bacteria.
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PMID:Anaerobic survival of Pseudomonas aeruginosa by pyruvate fermentation requires an Usp-type stress protein. 1638 55

Salmonella typhimurium is a Gram-negative bacterium responsible for human diseases including gastroenteritis and typhoid fever and its quorum sensing system is currently being intensively researched. Molecular modeling and binding site analysis of SdiA homolog, a putative quorum sensor of the LuxR family and responsible for S. typhimurium pathogenecity revealed a high structural homology of their active site with three other LuxR family proteins LasR from Pseudomonas aeruginosa, TraR from Agrobacterium tumifaciens and CviR from Chromobacterium violaceum. The results show that all the LuxR family proteins harbor three conserved amino acids Tryptophan (W67) and Aspartic acid (D80) for formation of hydrogen bridges and Tyrosine (Y71) for the hydrophobic interactions (corresponding to their position in S. typhimurium SdiA) with acyl homoserine lactones (AHL)-dependent transcriptional regulators. However, in addition to the above conserved residues, Arginine (R60) also plays an important role in S. typhimurium SdiA binding with its AHL auto inducers and the complex is found to be stronger because of the interactions between nitrogen atoms of Arginine with the carbonyl oxygen in the lactone ring of AHL. The specific binding patterns would be helpful in guiding both enzymatic studies as well as design of specific inhibitors to overcome S. typhimurium pathogenecity.
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PMID:Molecular modeling and active site analysis of SdiA homolog, a putative quorum sensor for Salmonella typhimurium pathogenecity reveals specific binding patterns of AHL transcriptional regulators. 2266 Sep 44

The aim of this study was to explore the effects of saponins on the rumen microbiota and the ruminal metabolome. Alfalfa hay (AH) and soybean hulls (SH) were used as fiber sources for the control diets. The AH and SH diets were supplemented with tea saponins resulting in two additional diets named AHS and SHS, respectively. These 4 diets were fed to 24 young male Holstein cattle (n = 6 per diet). After 28 days of feeding, the rumen fluid from these cattle was collected using an oral stomach tube. Illumina MiSeq sequencing and ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) were used to investigate the changes in the ruminal microbes and their metabolites. The relative abundance of Prevotellaceae_YAB2003 increased, while Ruminococcaceae_NK4A214 and Lachnospiraceae_NK3A20 decreased in SHS and AHS compared to SH and AHS, respectively. Feeding SHS resulted in higher ruminal concentrations of squalene, lanosterol, 3-phenylpropanoic acid, and citrulline compared to SH. The different microbial genes predicted by Tax4Fun were involved in amino sugar and nucleotide sugar metabolism. The pathways of arginine and proline metabolism, purine metabolism, and pyrimidine metabolism were enriched by different metabolites. Moreover, in the SH group, a positive correlation was observed between Prevotella_1 (Bacteroidetes), Prevotellaceae_YAB2003 (Bacteroidetes), and Christensenellaceae_R.7 (Firmicutes), and the metabolites, including citrulline, lanosterol, and squalene. The increased abundances of Prevotella_1, Ruminococcaceae_UCG.002, and Prevotellaceae_YAB2003 might result in increased fiber digestion and nutrient utilization but nutrient digestion was not measured in the current study. In summary, saponins have the ability to modulate the ruminal microbial community and ruminal metabolites and thus affect the rumen environment. However, the response seems to be dependent on the composition of the basal diet. This study provides a comprehensive overview of the microbial and biochemical changes in the rumen of cattle fed saponins.
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PMID:Saponin-Induced Shifts in the Rumen Microbiome and Metabolome of Young Cattle. 3087 43