ABSTRACT
The DevSR (DosSR) two-component system, which is a major regulatory system involved in oxygen sensing in mycobacteria, plays an important role in hypoxic induction of many genes in mycobacteria. We demonstrated that overexpression of the kinase domain of Mycobacterium tuberculosis (Mtb) PknB inhibited transcriptional activity of the DevR response regulator in Mycobacterium smegmatis and that this inhibitory effect was exerted through phosphorylation of DevR on Thr180 within its DNA-binding domain. Moreover, the purified kinase domain of Mtb PknB significantly phosphorylated RegX3, NarL, KdpE, TrcR, DosR, and MtrA response regulators of Mtb that contain the Thr residues corresponding to Thr180 of DevR in their DNA-binding domains, implying that transcriptional activities of these response regulators might also be inhibited when the kinase domain of PknB is overexpressed.
Subject(s)
Cell Hypoxia/genetics , Mycobacterium smegmatis/genetics , Mycobacterium tuberculosis/genetics , Protein Serine-Threonine Kinases/genetics , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA-Binding Proteins , Gene Expression Regulation, Bacterial/genetics , Humans , Mycobacterium smegmatis/metabolism , Mycobacterium tuberculosis/metabolism , Mycobacterium tuberculosis/pathogenicity , Oxygen/chemistry , Oxygen/metabolism , Phosphorylation , Protamine Kinase/genetics , Protamine Kinase/metabolism , Protein Kinases/genetics , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Tuberculosis/genetics , Tuberculosis/microbiologyABSTRACT
The Pd-catalyzed bisarylation of pyrroles with aryl iodides on water is described. The reaction proceeds under mild reaction conditions, i.e., relatively low temperature (40 °C) and phosphine-free.
ABSTRACT
The effects of aging process on the ginsenosides and antioxidant activity of ginseng was investigated. Fresh ginseng roots were aged in oven at 70 or 80 °C for 7, 14, 21, or 28 d. Their ginsenosides, phenolics, and antioxidant activity were analyzed. Ginseng aged at 80 °C for 14 d exhibited the highest amounts of total saponins and phenolics. It also showed markedly higher free radical scavenging activity, reducing power, and ferrous ion chelating ability than the other aged ginsengs. The ginsenosides Rb1 , Rb3 , Rg3 , Re, Rg1 , and Rg2 were generated during aging. The Rg2 was the most abundant ginsenoside in aged ginseng, with samples treated at 80 °C for 14 d having the highest amount. These findings provide the first evidence that aging, particularly at 80 °C for 14 d, could increase the bioactive compounds, indicating that this heating process may be useful in enhancing the biological activity of ginseng. PRACTICALAPPLICATION: Ginseng has long been recognized for its various health beneficial effects. The present study showed that aging of ginseng roots at 80 °C for 14 d substantially increased the amount of bioactive compounds ginsenosides and phenolics and enhanced the antioxidant activity. The food industry could use the aging process to improve the functional quality of ginseng.
