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Stephen A. Mills, Ph.D.
Department of Chemistry and Biochemistry Office: ST 485 Phone: (619) 260-7564 Email: smills@sandiego.edu
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B.S. University of Illinois at Urbana-Champaign
M.S. University of California, Berkeley, Advisor: Paul A. Bartlett
Ph.D. University of California, Berkeley, Advisor: Judith P. Klinman
Post-doctoral Fellow, University of
California, Berkeley, Advisor: Michael A. Marletta
Courses Taught
Chemistry 301 Organic Chemistry, syllabus
Chemistry 301L Organic Chemistry Lab, syllabus
Chemistry 302 Organic Chemistry II, S07, syllabus
Chemistry 302L Organic Chemistry II Lab, syllabus
Chemistry 331 Biochemistry, syllabus
Chemistry 335 Biochemistry Lab, syllabus
Chemistry 396W Research Methods, syllabus
Chemistry 494 Special Topics: Enzyme Kinetics and Mechanism, syllabus
Research
Interests
The theme of
research in our lab is to understand the role of metals in
proteins. We are
interested in how the specific metals get into the proteins and
why the specific metals are important for the function of the
protein. A primary
technique used in our lab is metal substitution. We then use a variety
of techniques to evaluate the effect of different metals on the
function of the protein, including enzyme kinetics, gel-shift
assays, UV-vis and fluorescence spectroscopy.
Specific Systems under
study:
Oxygen
Activation in the Copper Amine Oxidases (CAOs)
The
copper
amine oxidases (CAOs) are a family of enzymes that oxidize
amines using a unique, protein-bound cofactor,
trihydroxyphenylalanine quinone (TPQ), and a Cu(II) ion. The
cupric ion in these proteins is important for formation of the
cofactor and for catalysis once the cofactor is in place. We are
examining the role of copper in oxygen activation by these
enzymes. More information
Ferric Uptake Regulator Ð Fur selected references
Fur
is
an iron-sensing protein that is a key part of bacterial iron
metabolism. When there is sufficient iron in the cell, iron
binds to Fur and activates the protein to bind DNA. Upon binding
DNA, Fur turns off expression of iron importing proteins and
prevents the buildup of toxic iron levels. If metals, other than
iron, activate Fur for DNA binding, iron import can be turned
off when it should remain on and starve the cell for iron. We
are examining the affinity and selectivity of Fur from several
different bacteria for various metals, including Mn, Fe, Co, and
Zn to understand how selective the protein needs to be for
proper bacterial growth. By examining Fur homologues, with known
primary sequence, from various bacterial species we hope to
identify specific amino acids that are important for metal
selectivity. More information
CoaR Ð A cobalt-specific regulatory protein selected references
This
is
the only known regulatory protein specific for Co in bacteria.
It is a part of the vitamin B12 biosynthetic pathway. Little is
known about this protein except that it responds to Co and a B12
precursor Ð hydrogenobyrinic acid. We want to examine its
selectivity for cobalt over other first-row transition metals
and explore the effect of hydrogenobyrinic acid on metal
affinity.
CAO References
Mills,
S., D. Brown, et al. (2012). "Cobalt substitution supports an
inner-sphere electron transfer mechanism for oxygen reduction in
pea seedling amine oxidase." Journal of Biological Inorganic
Chemistry 17(4): 507-515. link
Mills,
S. A., Y. Goto, et al. (2002). "Mechanistic comparison of the
cobalt-substituted and wild-type copper amine oxidase from
Hansenula polymorpha." Biochemistry 41(34):
10577-10584. link
Mure,
M., S. A. Mills, et al. (2002). "Catalytic mechanism of the topa
quinone containing copper amine oxidases." Biochemistry
41(30): 9269-9278. link
McHugh,
J. P., F. Rodriguez-Quinones, et al. (2003). "Global
iron-dependent gene regulation in Escherichia coli. A new
mechanism for iron homeostasis." J Biol Chem 278(32):
29478-29486. link
Mills, S.
A. and M. A. Marletta (2005). "Metal binding characteristics and
role of iron oxidation in the ferric uptake regulator from
Escherichia coli." Biochemistry 44(41):
13553-13559. link
Pohl, E.,
J. C. Haller, et al. (2003). "Architecture of a protein central
to iron homeostasis: crystal structure and spectroscopic
analysis of the ferric uptake regulator." Mol Microbiol
47(4): 903-915. link
Rutherford,
J. C., J. S. Cavet, et al. (1999). "Cobalt-dependent
transcriptional switching by a dual-effector MerR-like protein
regulates a cobalt-exporting variant CPx-type ATPase." J
Biol Chem 274(36): 25827-25832. link
Scott, A.
I. (2003). "Discovering nature's diverse pathways to vitamin
B12: a 35-year odyssey." J Org Chem 68(7):
2529-2539. link
Tottey, S.,
D. R. Harvie, et al. (2005). "Understanding how cells allocate
metals using metal sensors and metallochaperones." Acc Chem
Res 38(10): 775-783. link