The RNA polymerase "switch region" is a target for inhibitors.

The alpha-pyrone antibiotic myxopyronin (Myx) inhibits bacterial RNA polymerase (RNAP). Here, through a combination of genetic, biochemical, and structural approaches, we show that Myx interacts with the RNAP "switch region"--the hinge that mediates opening and closing of the RNAP active center cleft--to prevent interaction of RNAP with promoter DNA. We define the contacts between Myx and RNAP and the effects of Myx on RNAP conformation and propose that Myx functions by interfering with opening of the RNAP active-center cleft during transcription initiation. We further show that the structurally related alpha-pyrone antibiotic corallopyronin (Cor) and the structurally unrelated macrocyclic-lactone antibiotic ripostatin (Rip) function analogously to Myx. The RNAP switch region is distant from targets of previously characterized RNAP inhibitors, and, correspondingly, Myx, Cor, and Rip do not exhibit crossresistance with previously characterized RNAP inhibitors. The RNAP switch region is an attractive target for identification of new broad-spectrum antibacterial therapeutic agents.

Effects of melatonin and zinc on glycemic control in type 2 diabetic patients poorly controlled with metformin.

OBJECTIVE: This project was designed to evaluate the effects of melatonin and zinc on the glycemic control in type 2 diabetes mellitus (T2DM) patients with inadequate response to the oral hypoglycemic agent metformin. METHODS: A placebo controlled, double-blind clinical trial was performed at the Specialized Center for Endocrinology and Diabetes, Al-Rusafa Directorate of Health, Baghdad, Iraq during the period from February to July 2005, in which 46 type 2 diabetic patients were selected and allocated into 3 groups, these groups were treated with single daily oral doses of both 10 mg melatonin and 50 mg zinc acetate alone; 10 mg melatonin and 50 mg zinc acetate in addition to the regularly used metformin or placebo, given at bed time for 90 days. We measured the fasting plasma glucose (FPG), glycated hemoglobin (HbA1C) and serum C-peptide before starting the treatment (zero time) and after 30 and 90 days of treatment. We also performed post-prandial glucose excursion test (PPGE) for selected patients from the second and third groups before starting the treatment and after 90 days. RESULTS: Daily administration of melatonin and zinc improved the impaired fasting and post-prandial glycemic control and decreased the level of glycated hemoglobin; addition of this treatment regimen in combination with metformin improved the tissue responses to this oral hypoglycemic agent. CONCLUSION: The combination of melatonin and zinc acetate, when used alone or in combination with metformin improves fasting and post-prandial glycemic control in T2DM patients.

Ciliotherapy: a novel intervention in polycystic kidney disease.

BACKGROUND: Ciliopathies are a group of diseases associated with abnormal structure or function of primary cilia. Ciliopathies include polycystic kidney disease (PKD), a pathology associated with vascular hypertension. We previously showed that cilia length regulates cilia function, and cilia function is required for nitric oxide (NO) biosynthesis in endothelial cells. Because patients with PKD show abnormal sensory cilia function, the aim of our current study was to search for a targeted therapy focused on primary cilia, which we refer to as 'ciliotherapy'. METHODS AND RESULTS: In the present studies, our in vitro analyses refined fenoldopam as an equipotent and more specific dopaminergic agonist to regulate cilia length and function. Our in vivo studies indicated that fenoldopam increased cilia length and serum NO thereby reducing blood pressure in a PKD mouse model. Our crossover, multicenter, double-blind and placebo-controlled clinical study further indicated that cilia-targeting therapy showed an overall reduction in mean arterial pressure in PKD patients. CONCLUSIONS: Overall, our studies provide the first evidence of ciliotherapy as an innovative intervention in patients with abnormal primary cilia.

Effects of melatonin and zinc on lipid profile and renal function in type 2 diabetic patients poorly controlled with metformin.

Glycemic control and prevention of secondary complications are the most important goals of using pharmacologic treatment of diabetes mellitus (DM). The inadequate responses to oral hypoglycemic agents may be attributed to inadequate postreceptor events even when insulin levels are quite sufficient, and associated with oxidative stress induced by long-term hyperglycemia. The administration of antioxidants such as melatonin and zinc may improve tissue responses to insulin and increase the efficacy of drugs, e.g. metformin, which act through this pathway. This project was designed to evaluate the effects of melatonin and zinc on the lipid profile and renal function in type 2 DM patients poorly controlled with metformin. A placebo-controlled, double-blind clinical trial was performed in which 46 type 2 diabetic patients were selected and allocated into three groups. These groups were treated with single daily oral doses of both 10 mg of melatonin and 50 mg of zinc acetate alone: 10 mg of melatonin and 50 mg of zinc acetate in addition to the regularly used metformin or placebo, given at bedtime for 90 days. Fasting lipid profiles and microalbuminuria (MAU) were measured before initiating the treatments (zero time) and after 30 and 90 days of treatment. Daily administration of melatonin and zinc improved the impaired lipid profile and decreased the level of MAU; the addition of this treatment regimen in combination with metformin improved the tissue responses to this oral hypoglycemic agent. In conclusion, the combination of melatonin and zinc acetate, when used alone or in combination with metformin, improves DM-related complications such as the impaired lipid profile and MAU in type 2 DM patients.

Inhibition of bacterial RNA polymerase by streptolydigin: stabilization of a straight-bridge-helix active-center conformation.

We define the target, mechanism, and structural basis of inhibition of bacterial RNA polymerase (RNAP) by the tetramic acid antibiotic streptolydigin (Stl). Stl binds to a site adjacent to but not overlapping the RNAP active center and stabilizes an RNAP-active-center conformational state with a straight-bridge helix. The results provide direct support for the proposals that alternative straight-bridge-helix and bent-bridge-helix RNAP-active-center conformations exist and that cycling between straight-bridge-helix and bent-bridge-helix RNAP-active-center conformations is required for RNAP function. The results set bounds on models for RNAP function and suggest strategies for design of novel antibacterial agents.