Erika A. Taylor, Ph.D. Assistant Professor of Chemistry (860) 685-2739  eataylor@wesleyan.edu
Biological Chemistry: Research focusing on enzyme mechanism determination, gene function assignment, transition-state and mechanism-based inhibitor design, and directed evolution of enzyme function Biofilms and Bacterial Surface Polysaccharides Extracellular sugar molecules are important for modulating cell-cell communication for both inter- and intra-species interactions. In Vibrio cholerae, and other gastrointestinal pathogens, complex sugar structures composed of both lipopolysaccharides (LPS) and capsular polysaccharides (CPS) are integral for bacterial adhesion and biofilm formation, two functions that contribute to pathogenicity. These complex sugar structures have been isolated and identified from various organisms, however their assembly, their in vivo structures, and structural modifications resulting from stress and environmental adaptation remain to be fully elucidated. The purpose of this research is to provide a comprehensive analysis of the dynamic structure and function of the major surface components of various Vibrio species as a means to better understand bacterial pathogenicity of this genus and ultimately to develop novel bacterial therapeutic agents. Two major aspects of this project are (1) the characterization of the glycosyltransferase enzymes that assemble the exopolysaccharides and (2) the dynamic characterization of the in vivo exopolysaccharide structures of both planktonic and biofilm forming stages. Glycosyltransferase characterization will involve the cloning, expression and purification of these enzymes to allow the elucidation of the function, substrate specificity and necessity (based upon viability of gene knockouts) of each enzyme. Since LPS biosynthesis is required for biofilm formation, many glycosyltransferases are anticipated to be necessary for this growth mode, and also therefore linked to virulence. Development of inhibitors, based upon transition state structure, for those enzymes linked to virulence could lead to the development of novel therapeutic agents. In vivo characterization of the dynamic polysaccharide structures would involve high-resolution magic-angle spinning (HR-MAS) NMR of whole intact cells grown in multiple environments in order to characterize structural changing conditions. The vastly different morphologies of the planktonic and biofilm stages, observable under a microscope, suggest numerous changes in glycosylation occur during the conversion between these two stages. Direct observation, without isolation, will allow for the characterization of the physiologically important interactions and three dimensional features of these sugar structures.   Biofuels  Increased interest in biomass conversion to biofuels has led to critical evaluation of the environmental impact of non-fossil fuel carbon sources, which in turn has revealed surprising problems associated with biofuel development efforts of major biomass sources (i.e. corn, sugarcane, soy). An accounting of the total environmental impact, factoring in rising food costs, deforestation, and other ancillary effects, suggests that almost half of the biofuel sources currently under consideration can be more environmentally harmful than fossil fuels, thereby necessitating the pursuit of alternate carbon sources for biofuel production.  One potential source is lignin, the second most abundant polymer in nature and a major waste product of the paper industry (50 million tons produced per year). The immense quantities of lignin produced annually and the recent efforts to increase lignin availability for utilization (only 2% was used commercially in 2004)3 make lignin-derived aromatic compounds an attractive carbon source for biofuel development.  Enzymes catalyzing key steps in the lignin catabolism pathway have been identified, however their incomplete enzymological characterization warrants their further investigation. As part of my long-term goal of developing enzymological means for improving efficiency of biofuel production, this research project is intended to accomplish three goals: 1) Enzymatic characterization of the dioxygenase enzymes involved in the degradation of lignin-derived aromatic compounds; 2) Targeted mutagenesis and directed evolution of the lignin degrading dioxygenases to increase substrate promiscuity thereby creating an enzyme for potential use in industrial-scale degradation of lignin using engineered bacteria; 3) Identification and characterization of enzymes evolutionarily related to these dioxygenases, thus creating the foundation for defining a new superfamily containing these lignin degrading dioxygenases. The proposed examination of dioxygenases responsible for lignin catabolism involves exploration of a new class of aromatic ring cleaving enzymes. These dioxygenases are unique when compared to previously characterized dioxygenases (including members of the VOC and Cupin superfamilies), in that they have evolved from an as yet undefined superfamily. Characterization of known PCA superfamily catabolic dioxygenases (DesZ, DesB, and LigAB) and other related enzymes, including analysis of substrate specificity, mechanism and physiological structure, should reveal more clearly the basis for differences between this class and other known dioxygenases enzyme families. Exploration of diverged members of this new unclassified superfamily will also facilitate discovery of new functions and help define the scope of possible reactions that can be catalyzed by this structural fold. The Taylor Group

 
Undergraduate Research Assistants:

Graduate Research Assistants:

Taylor Laboratory Alums

Selected Publications

• Li, L., et al. and Taylor, E. A., Second-sphere amino acids contribute to transition-state structure in bovine purine nucleoside phosphorylase. Biochemistry, 2008, 47, 2577-2583.
   
• Taylor, E. A.; Rinaldo-Matthis, A.; Li, L.; Ganhem, M.; Hazleton, K. Z.; Cassera, M. B; Almo, S. C.; Schramm, V. L., “Anopheles gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure and Inhibition,” Biochemistry, 2007, 46, 12405-12415.
   
• Luo, M.; Singh, V.; Taylor, E. A.; Schramm, V. L., “Transition State Structures of Human, Bovine and
  Plasmodium falciparum Adenosine Deaminases,” Journal of the American Chemical Society, 2007, 129, 8008-8017.
   
• Taylor, E. A.; Clinch, K.; Kelly, P. M.; Li, L.; Evans, G. B.; Tyler, P. C.; Schramm, V. L., “Acyclic Ribooxacarbenium Ion Mimics as Transition State Analogues of Human and Malarial Purine Nucleoside Phosphorylases,” Journal of the American Chemical Society, 2007, 129, 6984-6985.
   
• Tyler, P. C.; Taylor, E. A., Froehlich, R. F. G.; Schramm, V. L., “Synthesis of 5'-Methylthio Coformycins:
  Specific Inhibitors for Malarial Adenosine Deaminase,” Journal of the American Chemical Society, 2007, 129, 6872-6879.
   
• Taylor Ringia, E. A.; Tyler, P. C.; Evans, G. B.; Furneaux, R. H.; Murkin, A. S.; Schramm, V. L., "Transition State Analogue Discrimination by Related Purine Nucleoside Phosphorylases," Journal of the American Chemical Society, 2006, 128, 7126-7127.
   
• Taylor Ringia, E. A., Schramm, V. L., "Transition States and Inhibitors of the Purine Nucleoside Phosphorylase Family," Current Topics in Medicinal Chemistry, 2005, 5, 1237-1258.
   
• Lewandowicz, A; Taylor Ringia, E. A.; Ting, L.-M.; Kim, K; Tyler, P. C.; Evans, G. B.; Zubkova, O. V.; Mee, S.; Painter, G. F.; Lenz, D. H.; Furneaux, R. H.; Schramm, V. L., "Energetic Mapping of Transition State Analogue Interactions with Human and Plasmodium falciparum Purine Nucleoside Phosphorylases," Journal of Biological Chemistry, 2005, 280, 30320-30328.
   
• Ting, L.-M.; Shi, W.; Lewandowicz, A.; Singh, V.; Mwakingwe, A.; Birck, M. R.; Taylor Ringia, E. A.; Bench, G.; Madrid, D. C.; Tyler, P. C.; Evans, G. B.; Furneaux, R. H.; Schramm, V. L.; Kim, K., "Targeting a Novel Plasmodium falciparum Purine Recycling Pathway with Specific Immucillins," Journal of Biological Chemistry, 2005, 9547 - 9554.
   
• Thoden, J. B.; Taylor Ringia, E. A.; Garrett, J. B.; Gerlt, J. A.; Holden, H. M.; Rayment, I., "Evolution of Enzymatic Activity in the Enolase Superfamily: Structural Studies of the Promiscuous o-Succinylbenzoate Synthase from Amycolatopsis," Biochemistry, 2004, 42, 5716-5727.
   
• Taylor Ringia, E. A.; Garrett, J. B.; Thoden, J. B.; Holden, H. M.; Rayment, I.; Gerlt, J. A., "Evolution of Enzymatic Activity in the Enolase Superfamily: Functional Studies of the Promiscous o-Succinylbenzoate Synthase from Amycolatopsis," Biochemistry, 2004, 43, 224-229.
   
• Klenchin, V.A.; Taylor Ringia, E. A., Gerlt, J. A.; Rayment, I., "Evolution of Enzymatic Activity in the Enolase Superfamily: Structural and Mutagenic Studies of the Mechanism of the Reaction Catalyzed by o-Succinylbenzoate Synthase from Escherichia coli," Biochemistry, 2003, 42, 14427-14433.
   
• Taylor, E. A.; Palmer, D. R. J.; Gerlt, J. A., "Lesser "Burden Borne" by o-Succinylbenzoate Synthase: An "Easy" Reaction Involving a Carboxylate Carbon Acid," Journal of the American Chemical Society, 2001, 123, 5824-5825.
   
• Thompson, T. B.; Garrett, J. B.; Taylor, E. A.; Meganathan, R.; Gerlt, J. A.; Rayment, I., "Evolution of Enzymatic Activity in the Enolase Superfamily: Structure of o-Succinylbenzoate Synthase from Escherichia coli in Complex with Mg²⁺ and o-Succinylbenzoate," Biochemistry, 2000, 39, 10662-10676.

Education


B.S.    1998  University of Michigan, Ann Arbor
Ph.D.  2004  University of Illinois, Urbana-Champaign 

[Chemistry] [Wesleyan] Updated: July 16, 2009 (EAT/rncb)