Fragment-based screening for inhibitors of bacterial enzymes diguanylate and diadenylate cyclases using X-ray crystallography

• Grant number: 13/23163-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: February 01, 2014
• End date: January 31, 2015
• Field of knowledge: Biological Sciences - Biophysics - Molecular Biophysics
• Principal Investigator: Marcos Vicente de Albuquerque Salles Navarro
• Grantee: Helton José Wiggers
• Supervisor: Frank von Delft
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: University of Oxford, England
• Associated to the scholarship: 10/19109-4 - Design of Diguanilate Cyclase Inhibitors Involved in the Formation of Bacterial Biofilms, BP.PD

Abstract

Biofilm formation by microorganisms causes persistent infections to be resistant to treatment with anti-bacterial agents. As biofilm infections significantly contribute to patient morbidity and substantial healthcare costs, novel strategies to treat these infections are urgently required. Nucleotide second messengers, c-di-GMP and c-di-AMP, are major regulators of biofilm formation and associated antibiotic tolerance: in general elevated levels of c-di-GMP account for increased biofilm formation, while deletion of enzymes responsible for c-di-GMP biosynthesis abolishes bacterial biofilm formation; and c-di-AMP has also been implicated. Hence, the enzymes diguanylate cyclase (DGC) and diadenylate cyclase (DAC), responsible for the biosynthesis of c-di-GMP and c-di-AMP respectively, are attractive targets for the development of drugs against bacterial infections. The aim of this study is to apply a fragment-based approach to generate inhibitors for enzymes DGC and DAC from the pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus, respectively. Using the platform for medium throughput fragment screening by crystal structure available at Diamond Light Source via the SGC, both DGC and DAC enzymes will be tested against Diamond's general fragment library, and hits verified by Isothermal Titration calorimetry to obtain the thermodynamic parameters of binding. Identifying diverse molecular scaffolds will allow the development active compounds that can be employed as probe compounds for understanding the physiological mechanisms of action of DGC and DAC; will allow chemically validating them as anti-bacterial targets; will allow exploring chemotypes for their ability to penetrate biofilms; and ultimately, will provide starting points for the generation of novel bioactive compounds with anti-biofilm and/or anti-bacterial activity. (AU)