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Grover Paul Miller, Ph.D.
Assistant Professor
NIH postdoctoral fellow, Vanderbilt University, 1999-2001
Ph.D., Pennsylvania State University, 1997
B.S., Louisiana State University, 1992
Research Specialty:
Structure, function, and evolution of cytochrome P450s
Major areas of
interest include the metabolism of fatty acids in signaling processes and the
bioactivation of halogenated hydrocarbons by cytochrome P450s (CYP, P450) from a
biochemist’s perspective. Several approaches are being used to understand the
catalytic mechanisms of the cytochrome P450 enzymes, including site-directed and
random mutagenesis, kinetic analysis, and substrate-activity relationships. As a
complement to those efforts, we employ biophysical methods to assess the
function of protein interactions with P450 complex partners, substrate, and
membrane within the context of the P450 catalytic cycle. The long-term goal of
our research is to identify the factors that modulate P450 function and
establish a correlation between P450 activity and biological processes.
Research Interests
Understanding the dedication to partnering in the P450 complex
Even though the biological significance of cytochrome P450 activity has long
been recognized, an adequate structural description of the microsomal P450
system remains elusive. Localized to the endoplasmic reticulum, the microsomal
P450 system is best considered to be an aggregate of multiple discreet P450s
associating with redox partners, cytochrome P450 reductase (CPR) and in some
cases cytochrome b5 (cyt b5). CPR contains one molecule of FAD and FMN and
serves as an obligate redox component for practically all P450s, yet CPR is
outnumbered at least by 40:1 relative to P450s. Thus, P450 catalysis must derive
from successful competition between P450s catalyzing oxidations and those that
are not. During the P450 catalytic cycle, redox partners transfer electrons to
P450 heme, which serves to activate oxygen to a strong perferryl oxidant species
capable of oxidizing an unactivated carbon hydrogen bond. Inefficient electron
transfer between P450 and the redox partner leads to the decomposition of
activated iron-oxo intermediates to form reactive oxygen species (ROS), e.g.
O2•- and H2O2, precursors for oxidative stress. Because the efficiency of P450
reactions depends on the coupling of these electron transfer events, a mechanism
must exist to selectively stabilize active P450 complexes to mediate substrate
oxidation within the microsomal aggregate of proteins.
The goal of on-going efforts is to map the surfaces of interaction among P450
complex partners and assess the modulations of these surfaces during the P450
catalytic cycle. Ultimately, these studies could shed light on the role of the
complex in determining substrate specificity, product profiles, and oxidative
stress in cells through uncoupling.
In search of a molecular "trigger" for autoimmunity
Autoimmunity was recently named one of the priority women's health issues by the
Office of Research on Women's Health, a unit of the National Institutes of
Health. Autoimmunity, which is the underlying cause of more than 80 serious
chronic illnesses, targets women approximately 75% of the time. Although
evidence supports the role of genes and hormones in autoimmunity, initiation of
the autoimmune process often requires an environmental trigger. Due to its
widespread commercial use and improper disposal, trichloroethylene (TCE) has
become a major environmental pollutant. Whereas most TCE studies have focused on
the toxicology and carcinogenicity of TCE on liver, lung, and kidney, chronic
TCE exposure has also been associated with the development of autoimmune
disease, including systemic lupus erythematosus (SLE), systemic sclerosis, and
fasciitis. Because P450 2E1 (CYP2E1) is primarily responsible for TCE
metabolism, we are studying the role of CYP2E1 catalysis in producing the
molecular “trigger” that serves as a forerunner for the development of
autoimmunity.
Selected publications
Miller, G. P. and Benkovic, S. J. (1998) Deletion of a Highly
Motional Residue Affects the Formation of the Michaelis Complex for Escherichia
coli Dihydrofolate Reductase. Biochemistry 37, 6327-6335. [Abstract]
Miller, G. P. and Benkovic, S. J. (1998) Strength of an Interloop Hydrogen Bond
Determines the Kinetic Pathway in Catalysis by Escherichia coli Dihydrofolate
Reductase. Biochemistry 37, 6336-6342. [Abstract]
Hosea, N. A., Miller, G. P., and Guengerich, F. P. (2000) Elucidation of
Distinct Binding Sites for Cytochrome P450 3A4. Biochemistry 39, 5929-5939. [Abstract]
Yun, C.-H., Miller, G. P., and Guengerich, F. P. (2000) Rate-determining Steps
in Phenacetin Oxidations by Human Cytochrome P450 1A2 and Selected Mutants.
Biochemistry 39, 11319-11329. [Abstract]
Miller, G. P., Wahnon, D. C., and Benkovic, S. J. (2001) Investigating the
Importance of Interloop Contacts during Catalysis by Escherichia coli
Dihydrofolate Reductase. Biochemistry 40, 867-875. [Abstract]
Yun, C.-H., Miller, G. P., and Guengerich, F. P. (2001) Oxidation of p-alkyoxyacylanilides
Catalyzed by Human Cytochrome P450 1A2. Biochemistry 40, 4521-4530. [Abstract]
Miller, G. P. and Guengerich, F. P. (2001) Binding and Oxidation of Alkyl
4-nitrophenyl Ethers by Rabbit Cytochrome P450 1A2: Evidence for two binding
sites. Biochemistry 40, 4762-4772. [Abstract]
Miller, G. P., Hanna, I. H., Nishimura, Y., and Guengerich, F. P. (2001)
Oxidation of Phenethylamine Derivatives by Cytochrome P450 2D6: The issue of
substrate protonation in binding and catalysis. Biochemistry 40, 14215-14223. [Abstract]
Guengerich, F. P., Miller, G. P., Hanna, I. H., Léger, S., Black, C., Chauret,
N., Silva, J. M., Trimble, L., Yergey, J. A., and Nicoll-Griffith, D. (2002)
Diversity in the Oxidation of Substrates by Cytochrome P450 2D6: Lack of a role
of aspartate 301-substrate electrostatic bonding. Biochemistry 41, 11025-11034.
[Abstract]
Guengerich, F. P., Miller, G. P., Hanna, I. H., Sato, H., and Martin, M. V.
(2002) Oxidation of Methoxyphenethylamines by Cytochrome P450 2D6: Analysis of
rate-limiting steps. J Biol Chem 277, 33711-33719. [Abstract]
Jamakhandi, A. P.,
Jeffus, B. C., Dass, V. R., and Miller, G. P.
(2005) Thermal inactivation of the reductase domain of cytochrome P450 BM3.
Archives
Biochem Biophys 439,
165-74. [Abstract]
Collom, S. L.,
Jamakhandi, A. P., Tackett, A. J., Radominska-Pandya, A. and
Miller, G. P. (2006) CYP2E1 Active
Site Residues in Substrate Recognition Sequence 5 Identified by
Photoaffinity Labeling and Homology Modeling.
Archives Biochem
Biophys, in press.
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E-mail: |
MillerGroverP@uams.edu |
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Office: |
(501) 526-6486 |
Biomed B421A |
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Lab: |
(501)
526-6487 |
Biomed B420 |
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FAX: |
(501) 686-8169 |
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