Inhibition of the DevSR Two-Component System by Overexpression of Mycobacterium tuberculosis PknB in Mycobacterium smegmatis.

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.

Phosphine-free palladium-catalyzed direct bisarylation of pyrroles with aryl iodides on water.

The Pd-catalyzed bisarylation of pyrroles with aryl iodides on water is described. The reaction proceeds under mild reaction conditions, i.e.

Influence of aging process on the bioactive components and antioxidant activity of ginseng (Panax ginseng L.).

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.