High-Performance Computational Molecular Docking for Potential Inhibitors of an Essential Enzyme of Burkholderia pseudomallei.

Melioidosis, caused by the rod-shaped bacteria Burkholderia pseudomallei, is thought to be an understudied and neglected disease. This life-threatening infection, endemic across tropical areas such as northern Australia and southeast Asia, is estimated to kill at least 89,000 people worldwide annually, though this number is thought to be a serious underestimation. The symptoms of this disease are non-specific, resembling other common illnesses, as the bacterium is highly adaptable and able to produce a range of clinical manifestations depending on the infected tissue. Melioidosis, with its difficulty in diagnosis, high- lethality, increasing antibiotic resistance, and airborne potential has led many governments including the U.S. to consider the disease a bioterror threat, as with other pathogens such as anthrax and Ebola. Novel drug treatments are needed, in the face of increasing antibiotic resistance. In this research, we targeted one of the essential enzymes - GmhA - of Burkholderia pseudomallei for small molecule drug discovery The GmhA gene is necessary for the synthesis of heptoses which are utilized in virulence and antibiotic resistance. Through high-performance computing, virtual libraries of small molecules were docked against the x-ray crystallography model of the active site of the enzyme. The virtual screening programs, GOLD and VINA, predicted the strength of the binding interaction with higher scores reflecting a stronger interaction and the potential to inhibit the enzyme. In order to validate the programs for this protein, control ligands with similar physiochemical properties to the known substrate M7P were found. Screening these controls resulted in similar ranges of results for both the GOLD and VINA, with M7P scoring consistently with a GOLD score of roughly 55. After validation, thousands of small molecules from four libraries were docked to the protein structure, resulting in a consistent interquartile range of scores roughly 40-60. Significantly departing from this range, goserelin acetate scored the highest overall, with a GOLD score of 101.9. Wet lab work is being conducted on the BpGmhA target, with successful protein synthesis in E. coli from a pET expression vector resulting in affinity-purified protein elutions of the expected molecular weight of BpGmhA of 85.56 kDa. Elutions will be further tested with top virtually scoring ligands to verify inhibition properties predicted from the computational dockings. Promising ligands will be obtained and then evaluated through binding and enzymatic assays to verify their ability to inhibit the enzyme. If confirmed, these novel ligands may be potential candidates for further drug development to treat melioidosis.