Currently I am a postdoctoral research fellow in the Molecular Targets Laboratory at NCI-Frederick working under the supervision of Dr. Barry O’Keefe working towards the isolation and characterization of bioactive proteins purified from marine aqueous extracts. The extracts come from marine soft coral and sponges and represent distinct, complex microenvironments that have tremendous therapeutic potential. The macromolecules range from 18-40 kDa, have little sequence homology, and represent novel molecules with incredible potency, specificity, and selectivity.
My first postdoctoral research position worked Dr. Cichewicz’s Natural Products Discovery Group at the University of Oklahoma in the Chemistry and Biochemistry Department. My team specifically worked towards the optimization of the mammalian microbiome project (affectionately referred to as the Roadkill project) in efforts to identify novel anticancer and antimicrobial compounds from bacteria found naturally in mammalian flora. The bacterial isolates were taken from recently deceased mammals from the side of the road, isolated using a range of selective media and physical variation, fermented, extracted and tested against MRSA, Candida, and cancer cell-lines.
My graduate career examined the structure and function of adenylate forming enzymes under the supervision of Dr. Gulick at Hauptman-Woodward Institute for Structural Biology in Buffalo, NY. The Gulick Lab specifically focuses on the domain interactions between non-ribosomal peptide synthetases and tailoring enzymes required to facilitate NRP biosynthesis using X-ray crystallography with mechanism based inhibitors and kinetic analysis. Here I published three crystal structures (4DG8, 4DG9m and 4WD1) in two publications. My time in the Gulick lab is partially responsible for my fascination with biosynthesis of natural products.
The Structure of PA1221, a Non-Ribosomal Peptide Synthetase containing Adenylation and Peptidyl Carrier Protein Domains
This publication examined the interactions between an Adenylation domain that activates Valine and its cognate Peptidyl-Carrier Protein (PCP) utilizing functional and structural characterization. The 4DG9 structure resolved the PCP in the electron density that was trapped through the use of a mechanism-based inhibitor that mimics the transition state intermediate (phosphopantetheine-valine-adenosine monophsophate). This protein belongs to a cryptic biosynthetic operon from the opportunistic pathogen Pseudomonas aeruginosa and is the only wild-type example of an adenylation domain interaction with a PCP in a biologically relevant manner in the Protein DataBank.
The Structure of S. lividans Acetoacetyl-CoA Synthetase shows a Novel Interaction between the C-terminal Extension and the N-terminal Domain
This publication characterized a C-terminal extension interaction with the P-loop of the N-terminal domain of acetoacetyl CoA Synthetase. This structure is the first synthetase with the entire C-terminal extension resolved. The interaction has implications in catalytic efficiency as well as recognition by acetyltransferases, which inhibit the activity of this specific enzyme. The PDBID is 4WD1 (Proteins. 2015 Mar;83(3):575-81. doi: 10.1002/prot.24738. Epub 2015 Jan 5).
Opportunistic Sampling of Roadkill as an Entry Point to Accessing Natural Products Assembled by Bacteria Associated with Nonanthropoidal Mammalian Microbiomes
This publication summarizes the Roadkill Pipeline that was developed at the University of Oklahoma. We swabbed recently deceased mammalian roadkill for bacterial isolates that were bioactive in MRSA, Candida, or Cancer assays. Specifically, the publication analyzes the sampling method and details the discovery and isolation of cyclolipodepsipeptides from Serratia sp., as well as analyzes the genome for the biosynthetic machinery responsible for the peptides.
Courtney Aldrich’s lab at the University of Minnesota synthesized the Valine-vinyl sulfonamide that trapped the PCP in a relevant interaction with the adenylation domain. This type of mechanism-based inhibitor was also used in an engineered Aden:PCP structure solved by Dr. Jesse Sundlov.