Institution: Interamerican University Metro Campus

Email: acolom@intermetro.edu

Methicillin-resistant Staphylococcus aureus (MRSA) infections have become a serious threat in healthcare and community settings worldwide. Novel antibiotics are critically needed to broaden the medical treatments against MRSA infections. In 2014, Sanabria et al. demonstrated a significant antibacterial activity of the synthetic fatty acid 2- hexadecynoic acid (2-HDA) against MRSA. There is a gap in knowledge on of how 2- HDA acts at the molecular level, which has prevented the basic understanding of its inhibitory mechanism and the development of novel therapeutic strategies. The specific hypothesis of this project is that 2- HDA inhibits an enzyme involved in the synthesis of important fatty acids components of the cell membrane, specifically enoyl-ACP reductase (Fabl). Fabl is needed for the biosynthesis of phosphatidic acids, one of the components of bacterial membranes, which makes it an attractive drug target. We based our hypothesis on experimental evidence from (1) Sanabria et al.demonstrating that the cytotoxic action of 2-HDA is due to its ability to inhibit bacterial fatty acids synthesis, hence compromising the cell membrane integrity. (2) Zheng at al. demonstrated that a C18 unsaturated fatty acid binds specifically to Fabl from E. Coli and S. aureus through a mixed inhibition mechanism. The objective of this application is to identify atomic interactions between 2-HDA and Fabl that are vital for the binding mode of the ligand. The rationale for the proposed research is that once key molecular interactions important to 2-HDA's binding mode to Fabl are identified, pharmacological agents that inhibit this enzyme could be designed to treat MRSA infections more effectively. This inhibitor's role and mechanism of action have never been explored computationally. The specific aims are:1: To identify the most energetically favorable conformation of 2-HDA by optimizing its geometry. We will obtain the optimized geometry and electronic structure of 2-HDA by using the quantum­ chemistry modeling program Gaussian16 and its graphical user interface, GaussView. The optimized geometry will be docked to Fabl.
2: To identify the binding site of 2-HDA in Fabl. To accomplishthis aim we proposed using molecular docking methods from three software's packages: Maestro, SeeSAR, and MOE. Identifying the atomic interactions between the ligand and target is fundamental to insight on the mechanism of inhibition of this compound Impact: The expected outcome of this research is a comprehensive understanding, at a molecular level, of what region and amino acid residues of Fabl are involved in binding 2-HDA, what atomic interactions are necessary to have a favorable binding and a preliminary insight on the mechanism of inhibition of this novel compound.