Structural insights of metallo-beta-lactamase revealed an effective way of inhibition of enzyme by natural inhibitors.

Metallo-beta-lactamase (MBL) is a class of enzyme that catalyzes the hydrolysis of a broad range of beta-lactam antibiotics leading to the development of drug resistance in bacteria. Inhibition of MBL is therefore pursued as a potential way to increase the susceptibility of bacteria to beta-lactam antibiotics. In this study, MBL inhibitors from natural sources such as Eupalitin, Rosmarinic acid and Luteolin are used as a potential alternative to explore their effect. The crystal structure of MBL revealed a hydrolyzed Meropenem, which was undocked from the active center pocket to get the apo-protein. The apo-protein was re-docked with substrate, three known MBL inhibitors and natural compounds to prepare the starting structure in the current work and to draw conclusions. Further, to explore the efficiency of natural inhibitors, we analyzed the dynamic behavior of the enzyme over simulation time using molecular dynamics studies. Our results suggest that MBL enzyme adopted altered conformational state in the presence of natural inhibitor. This is because, the natural inhibitors were tried to occupy a different binding pocket in the enzyme by causing positional drift from the active center pocket. Here, the different binding pocket partly comprised of active site pocket and partly by a new region explored by ligand, making it inappropriate for substrate to occupy the active site. Thus natural inhibitors may be potential entities to target MBL. AbbreviationsADMEAbsorption, Distribution, Metabolism and ExcretionBBBBlood brain barrierCHARMMChemistry at Harvard Macromolecular MechanicsCOMCenter of MassCYP2D6Cytochrome P450 2D6DSDiscovery StudioESBLExtended Spectrum Beta-lactamasesFDAFood and Drug AdministrationGLASSGlobal antimicrobial resistance surveillance systemGROMACSGROningen MAchine for Chemical SimulationsKDEKernel Density Estimation PlotsMBLMetallo-beta-lactamaseMBL-CMetallo-beta-lactamase bound to L-CaptoprilMBL-EMetallo-beta -lactamase bound to EupalitinMBL-IMetallo-beta -lactamase bound to ImipenemMBL-LMetallo-beta -lactamase bound to LuteolinMBL-RMetallo-beta -lactamase bound to Rosmarinic acidMDMolecular DynamicsMMPBSAMolecular Mechanics Poisson - Boltzmann surface areaNPTNumber of atoms in the system, Pressure of the system and Temperature of the systemnsNano secondsNVTNumber of atoms in the system, Volume of the system, and Temperature of the systemPDBProtein Data BankRgRadius of GyrationRMSDRoot Mean Square DeviationRMSFRoot Mean Square FluctuationSASASolvent Accessible Surface AreaSPC/ESimple Point ChargeWHOWorld Health OrganizationCommunicated by Ramaswamy H. Sarma.