Dale Poulter
John A. Widtsoe and Distinguished Professor of Chemistry and Professor of Biochemistry
B.S. Louisiana State University
Ph.D. University of California, Berkeley
Dale Poulter's Lab Page
Dale Poulter's PubMed Literature Search
Research
My research group is interested in problems
at the interface between chemistry and biology. We are studying
the prenyl transfer enzymes in the isoprenoid biosynthetic pathway
to determine the mechanisms of the reactions they catalyze, how
the proteins promote catalysis, and phylogenetic relationships
among the enzymes.
The isoprenoid biosynthetic pathway is needed by all organisms
to produce essential compounds. There are two different ways that
nature synthesizes isopentenyl diphosphate (IPP) to dimethylallyl
diphosphate (DMAPP),the fundamental five-carbon building blocks
needed for isoprenoid biosynthesis. One of these pathways, the
mevalonate (MVA) route, was discovered in the late 1950’s
and until recently was assumed to be the only pathway to IPP and
DMAPP. Recently, a second route, the methylerythrose phosphate
(MEP) pathway, was discovered. We have cloned genes for several
of the enzymes in the MEP pathway in order to study their mechanisms
and to develop inhibitors that block the MEP pathway that have
potential applications as new antibacterial agents.
We are also studying several key enzymes in the pathway that catalyze
fundamental activation and bond forming reactions, including isomerization
DMAPP, the addition of IPP to allylic isoprenoid diphosphates
to make longer chains, and the cyclopropanation and rearrangement
reactions that convert farnesyl diphosphate (FPP) to squalene
during biosynthesis of cholesterol. Other enzymes we study are those catalyzing unusual alkylation reactions
that occur during the biosynthesis ergot alkaloids, the posttranslational
modification of proteins with isoprenoid chains, and the modification
of tRNA. We isolate genes for the enzymes we study, engineer plasmids
to overproduce the proteins, and carry out site-directed mutagenesis
to help determine the roles of specific amino acids in binding
and chemical catalysis. Work on these projects provides training
in a combination of chemical (synthesis, isolation-identification,
reaction mechanisms), microbiology (mutagenesis, isolation and
characterization of genes), molecular biological (cloning, site-directed
mutagenesis), and biochemical (enzyme purification, kinetics)
techniques.
Much of what we do relies heavily on modern analytical methods,
including high field multi-dimensional NMR, mass spectrometry,
and separation technology. We also draw on ideas and techniques
from chemistry and biology to design our experiments, including
developing news procedures for the synthesis of compounds, developing
new methods for measuring interactions between an enzyme and its
substrates, and using recombinant DNA technology to engineer bacterial
strains with new biosynthetic capabilities. It is the interdisciplinary
nature of what we do that is both challenging and exciting.
References
1. Lee S, Poulter CD (2006) Escherichia coli Type I Isopentenyl Diphosphate Isomerase: Structural and Catalytic Roles for Divalent Metals. J. Am. Chem. Soc. 128:11545-11550
2. Gauchet C, Labadie GR, Poulter CD (2006)Regio- and Chemoselective Covalent Immobilization of Proteins through Unnatural Amino Acids. J. Am. Chem. Soc. 128:9274-9275
3. Thulasiram HV, Phan RM, Rivera SB, Poulter CD (2006)Synthesis of Deuterium Labeled Derivatives of Dimethylallyl Diphosphate. J. Org. Chem. 71:1739-1741
4. Lherbet C, Pojer F, Richard SB, Noel JP, Poulter CD (2006)Absence of Substrate Channeling between Active Sites in the Agrobacterium tumefaciens IspDF and IspE Enzymes of the Methyl Erythritol Phosphate Pathway. Biochemistry 45:3548-3553
5. Cornish RM, Roth JR, Poulter CD (2006)Lethal mutations in the isoprenoid pathway of Salmonella enterica. J. Bacteriol. 188:1444-1450
6. Testa CA, Lherbet C, Pojer F, Noel JP, Poulter CD (2006)Cloning and Expression of IspDF from Mesorhizobium loti. Characterization of a Bifunctional Protein that Catalyzes Non-Consecutive Steps in the Methylerythritol Phosphate Pathway. Biochem. Biophys. Acta, 1764:85-96
7. Poulter CD (2006)Farnesyl Diphosphate Synthase. A Paradigm for Understanding Structure and Function Relationships in E-Polyprenyl Diphosphate Synthases” Phytochem. Reviews 5:17-26
8. Wu Z, Wouters J, Pouter CD (2005)Isopentenyl Diphosphate Isomerase. Mechanism-Based Inhibition by Diene Analogues of Isopentenyl Diphosphate and Dimethylallyl Diphosphte. J. Am. Chem. Soc. 127:17433-17438
9. Walker JR, Poulter CD (2005)Synthesis and Evaluation of 1-Deoxy-D-xylulose 5-Phosphate Analogs as Chelation Based Inhibitors of Methylerythritol Phosphate Synthase. J. Org. Chem. 70:9955-9959
10. de Ruyck J, Rothman SC, Poulter CD, Wouters J (2005)Structure of Thermus thermophilus type 2 isopentenyl diphosphates isomerase inferred from crystallography and molecular dynamics. Biochem. and Biophys. Res. Comm. 338:1515–1518
11. Fox DT, Poulter CD (2005)Mechanistic Studies with 2C-Methyl-D-erythritol 4-Phosphate Synthase from Escherichia coli. Biochemistry 44:8360-8368
12. Fox DT, Poulter CD (2005)Synthesis and Evaluation of 1-Deoxy-D-xylulose 5-Phosphoric Acid Analogs as Alternate Substrates for Methylerythritol Phosphate Synthase. J. Org. Chem. 70:1978-1985
14. Barkley SJ, Desai SB, Poulter CD (2004) Proton Exchange in Type II Isopentenyl Diphosphate Isomerase. Organic Letters 6:5019-5021
15. Barkley SJ, Desai SB, Poulter CD (2004) Type II Isopentenyl Diphosphate Isomerase from Synechocystis sp. Strain PCC 6803. J. of Bacteriology 8156-8158
16. Scholte A, Eubanks L, Poulter CD, Vederas J (2004) Synthesis and Biological Activity of Isopentenyl Diphosphate Analogs.” Bioorganic and Medical Chemistry 12:763-770
17. Testa CA, Cornish RM, Poulter CD (2004) The Sorbitol Phosphotransferase System is Responsible for the Transport of 2-C-Methyl D-Erythriotol into Salmonella enterica terovar Typhimurium. J. Bacteriology 186:473-480
18. Wouters J Oudjama Y, Stalon V, Droogmans L, Poulter CD (2004) Crystal Structure of the C67A Mutant of Isopentenyl Diphosphate Isomerase Complexed with a Mechanism-Based Irreversible Inhibitor. Proteins 54:216-221
19. Carrigan CN, Poulter CD (2003) Zinc is an Essential Cofactor for Type I Isopentenyl Diphosphate: Dimethylallyl Diphosphate Isomerase. J. Am. Chem. Soc. 30:9008-9009
20. Erickson H, Poulter CD (2003) Chrysanthemyl Diphosphate Synthase. The Relationship among Chain Elongation, Branching and Cyclopropanation Reactions in the Isoprenoid Biosynthetic Pathway. J. Am. Chem. Soc. 23:6885-6888

