Discovery of Novel Antimicrobial Agents
My research focuses on the understanding of the structure and function of natural therapeutic products. This work will provide a foundation for research aimed at understanding their efficacy for use in the treatment and prevention of human and animal diseases and as potential biological control agents in agriculture. The discovery of novel antimicrobials and the study of antimicrobial function have significant relevance towards the development of therapeutics aimed at treating life-threatening diseases. Moreover, much of what we have learned about protein synthesis, DNA replication, enzyme function, and membrane physiology comes from the study of antimicrobials. The structural and functional characterization of new antimicrobial agents will provide new insights into cellular processes and membrane physiology, as well as provide means to rationally design new analogs that target microbial function. The discovery of new enzymes involved in natural product synthesis also offers invaluable information for understanding the complexity of microorganisms and provide tools for synthetic chemistry applications.
My strength in this area of research lies in my cross disciplinary background, which encompasses antimicrobial development when I worked for Oragenics Inc. As a postdoctoral fellow at Oragenics Inc, I gained considerable amount of experience under the guidance of the distinguished Microbiology professor Dr. Jeffrey D. Hillman. It was here that I expanded my knowledge of Microbiology and learned several new biotechnology techniques involving preclinical testing of novel antimicrobials, which complemented my biophysical and molecular biology training at the University of Florida’s College of Medicine under the guidance of Dr. Arthur Edison. Our group laid the ground work for studies on the antibiotics mutacin 1140 and occidiofungin, i.e. production, purification and the structural determination, mechanism of action, and the assessment of their therapeutic potential. These studies are extremely important, given the rise in antibiotic resistance of Gram-positive pathogens and the need for new antifungal targets for treating serious fungal infection.
Research Interests
Novel peptide based antimicrobials are of great interest to my group. Whether ribosomally or non-ribosomally synthesized, these compounds often contain complex structures and systems leading to their production. The discovery of unique structures and ascertaining their role in antimicrobial function are a fascinating area of research. Additionally, gaining an understanding of the function of the enzymes leading to their production is equally as interesting, because these enzymes may have utility in enzymatically synthesizing and engineering unique compounds. My strength in this area of research lies in my cross disciplinary background, which encompasses bacterial cultivation, bacterial genetics, fermentation and process biochemistry, structural determination using biophysical applications such as NMR and Mass Spectrometry, and experience in chemical modification and synthesis of natural products.
The study of antimicrobials may lead to life saving therapies and help ensure a sustainable food supply. This in itself is enough to motivate my research efforts. However, there is more to antimicrobial research. This work also leads to a better understanding of microbial physiology and complexity of the processes that microorganisms undergo to maintain a sustainable niche.
Lanthipeptides (lantibiotics) are an interesting class of antibiotics. They are a structurally novel class of antibiotics (Class I bacteriocins) which can be divided into 5 subclasses based on differences in their chemistry and biosynthesis: Type A(I), Type A(II), Type B, Two-Component and those of unknown structures. Lanthipeptides possess sulfur-containing lanthionine rings and a large variety of unusual amino acids. This class of antibiotics is potent against a broad spectrum of Gram positive bacteria and has been known for decades but has not been extensively tested for their potential usefulness in treating infectious diseases. The main reason is that very little is known about the pharmaceutical potential of many of these antibiotics. This is primarily contributed to the difficulty of producing them in sufficient quantity and purity for preclinical and clinical tests. I have spent over a decade studying lanthipeptides, particularly mutacin 1140 which belongs to the Type A “nisin” group. My lab is currently working on approaches to make mutacin 1140 in sufficient amounts and purity to be cost effective. Furthermore, we are studying the biosynthetic pathway and structural regions of the antibiotic to determine their importance in bioactivity.
Antifungals are particularly important for the treatment of fungal infections in immunocompromised patients. Candidemia has a mortality rate of 30%–50% in cancer patients, and is a major complicating factor for the successful treatment of cancer. Fluconazole resistance is a serious problem, which results in an increase in mortality, prolonged hospital stay, and a substantial increase in healthcare costs. More appropriate antifungal treatment options may reduce the cost of treatment and mortality for cancer patients. Occidiofungin, a newly discovered antifungal isolated and characterized by our group, will be evaluated for its ability to treat serious fungal infections. Burkholderia contaminans MS14 was isolated from the soil showing suppression to brown patch disease of lawn grass. The antifungal compound was isolated from culture broth of MS14 and purified. The covalent structure of the antifungal compound named occidiofungin was determined by nuclear magnetic resonance (NMR) and mass spectrometry experiments. Occidiofungin was determined to have a unique chemical composition following structural characterization. Occidiofungin has met three significant criteria for the development of an antifungal for pre-clinical testing. First, it has a unique structure. Second, occidiofungin has a better spectrum of activity, rapid fungicidal activity, and novel mechanism of activity as compared to polyenes, azoles and echinocandins. Third, it has been shown to have minimal adverse effects and was well tolerated in a mouse toxicity study. Additional studies are necessary to determine its biological activity, acute toxicity, pharmacokinetics following different routes of administration, and its ability to treat a systemic infection. Our research is aimed at completing preclinical studies necessary for filing an Investigational New Drug Application with the Food and Drug Administration. These studies will promote our understanding of the compounds potential for treating serious fungal infections. Further experimentation will establish a basis for the development of occidiofungin for the treatment of serious fungal infections, which has a potential to change current clinical practice paradigms. Furthermore, we are studying the biosynthetic pathway of occidiofungin. These studies will facilitate an understanding of the biosynthetic enzymes potential for synthesizing novel variants of occidiofungin and their potential for synthetic chemistry applications.
Active Research Support
Award RP121002 (P.I.) 06/01/2012 – 05/31/2015
CPRIT
Examination of the Pharmacological Properties of a Novel Antifungal Named Occidiofungin
This proposal involves the pharmacokinetic and pharmacodynamic evaluation of a novel antifungal compound, named occidiofungin, for the treatment of a systemic Candida albicans infection.
Role: Principal Investigator
Completed Research Support
Award AI079897 (P.I.) 08/15/2008 – 05/31/2010
NIH-NIAID
Functional Characterization of the Site Specific Residues in Mutacin 1140
This proposal involves classical mutagenesis techniques to alter specific amino acids in the gene for mutacin 1140 production. These mutants will be screened for loss or enhancement of bioactivity in order to learn more about their ability for lateral assembly, lipid II binding, and the robustness of the post-translational modification machinery of the antibiotic.
Role: Principal Investigator
American Recovery and Reinvestment Act of 2009 (P.I.) 08/15/2009 – 05/31/2010
NIH-NIAID Supplemental Award to grant AI079897
Functional Characterization of the Site Specific Residues in Mutacin 1140
This supplement provides financial support for a minority Ph.D. student whose work is to characterize site directed mutants in the ribosomally synthesized lantibiotic mutacin 1140.
Role: Principal Investigator
Award 0749884 Hillman, J.D. (P.I.) 04/01/2008 – 03/31/2011
NSF – Phase II SBIR
Lantibiotic Synthesis Using Differentially Protected Orthogonal Lanthionines
My portion of this proposal is to confirm the covalent structure of the antibiotic Nisin synthesized by solid phase peptide synthesis using differentially protected orthogonal lanthionines and to characterize its bioactivity as compared to natural product nisin.
Role: Collaborator
Research Initiation Proposal (P.I.) 01/05/2007 – 01/04/2008
Mississippi State University Office of Research
Implementation of LctM use in solid phase peptide synthesis (LUIS) for the production of the antibiotic Nisin
This project involves producing and purifying the LctM enzyme that is capable of making thioether linkages. Goal is to determine the optimal conditions for making thioether linkages on peptides attached to a resin support, then attempt to make the antibiotic Nisin by solid phase peptide synthesis.
Role: Principal Investigator
Consulting Services
I specialize in evaluating investment opportunities in the biotechnology industry. Biotechnology is an exciting and fascinating area for investment opportunities. However, biotech investments can be risky and have been compared to playing the roulette table, as reported by David P. Hamilton in the Wall Street Journal on May 20th, 2004.
“Biotechnology is the people’s lottery,” says Thomas Eadington, a medical-technology entrepreneur turned investor in Newport Beach, Calif. “It’s like the ultimate roulette game. If you hit it, the returns are astronomical.”
My experiences and education enable me to be an effective Scientific Advisory Board member, which I would be willing to do for a select company. I have the experience and resources that enable me to effectively analyze the scientific merit and accuracy of a developing product’s claims.
Each proprietor of technology believes that their science will become the next blockbuster product. I will provide assistance to investors and companies before they make a financial investment. By no means does my recommendation guarantee the investment, but I will provide my clients with the experience and knowledge to make a more prudent investment.
I have over ten years of consulting experience. My clients include venture capital firms, legal firms, and angel investors. I have served as Project Director for Oragenics, Inc., which is actively involved in several health-related programs. I have overseen the development of several infectious disease projects, which entailed the development of novel antibiotics and the identification of vaccine and diagnostic targets for human pathogens. I have also served as a Director for the Able Trust Foundation through a gubernatorial appointment. During my involvement with the Able Trust, I served as Treasurer and Chaired the Finance Committee.
I received my MBA from the Warrington College of Business with an emphasis in finance and competitive strategy. I also received my Ph.D. in Medical Sciences from the College of Medicine at the University of Florida. Aside from my course studies in Microbiology, Neurophysiology and Biochemistry, I have a strong background in Molecular Biology, Microbiology, and Biological Chemistry techniques.
Former Student Placement
Adam Foxfire: Adam was isolating and characterizing the antibacterial properties of novel compounds from Burkholderia contaminans MS14. Dissertation Title: Antimicrobial Agents of Burkholderia Genus and Those Produced by Burkholderia contaminans MS14. Graduated in December 2020.
Steven Lai Hing,: Steven established in vitro assays for characterizing the activity of mutacin 1140 in combination with clinically approved antibiotics. His effort is to identify synergy and to determine the physiological basis for the synergy. Dissertation Title: Mutacin 1140 and Occidiofungin: Natural Products Isolated from Bacterial Sources and Their Potential Applications as Therapeutics. Graduated in December 2017. Current Position: Instructional Professor at Oakwood University in Georgia.
Jerome Escano: Jerry analyzed the propeptide of mutacin 1140 for structural elements that are important for processing the prepeptide and furthered our understanding of the post-translational modifications of the core peptide. Dissertation Title: Insights into the Biosynthesis of the Lantibiotic, Mutacin 1140. Graduated in December 2016. Current Position: UTMB Medical School Student.
Akshaya Ravichandran: Akshaya analyzed structural analogs of occidiofungin and furthered our understanding of the mechanism of action of occidiofungin. Dissertation title: Characterization and Development of Occidiofungin. Graduated in December 2016. Current Position: Scientist I, Analytical Sciences at Novavax. Prior Positions: Post-Doctoral scientist at Scripps Research Institute and Research Scientist at Sano Chemicals Inc., Texas.
Shawanda Wilson-Stanford: Dissertation Title: A Study of the Structural Integrity of Type A(I) Lantibiotics via Chemical Modification and Mutagenesis. Named the 2009 Department of Biological Sciences Research Assistant of the Year and the 2010 Research assistant of the year for the whole university. Graduated in August 2011. Current Position: Assistant Professor at Blinn College, Texas