Department of Chemistry and Biochemistry
Faculty and Staff Directory
F. Wayne Outten
Title: | Professor and Guy F. Lipscomb, Sr. Professor of Biochemistry / Biochemistry and Molecular
Biology Bioinorganic |
Department: | Chemistry and Biochemistry Department of Chemistry and Biochemistry |
Email: | outtenf@mailbox.sc.edu |
Phone: | 803-777-8151 |
Fax: | 803-777-9521 |
Office: | Office: GSRC 309 Lab: GSRC 303, 803-777-0669 Lab 2: GSRC 304 Lab 3: GSRC 321 Lab 4: GSRC 320 |
Resources: | CV [pdf] All Publications F. Wayne Outten Group Website PubMed ResearchGate Department of Chemistry and Biochemistry |
Education
B.S., 1995, College of William and Mary
Ph.D., 2001, Northwestern University
Honors and Awards
Research Corporation Cottrell Scholar, 2008-2010
Research Interests
Microbial metal metabolism, bioinorganic chemistry, microbial physiology, and microbial genetics; biochemical mechanisms of Fe-S cluster assembly; characterization of transition metal acquisition, trafficking, and storage systems and their transcriptional and post-transcriptional regulation during environmental stress.
Metal Trafficking and Metal Cofactor Assembly Under Stress Conditions
My broad research goal is to understand how homeostasis of essential transition metals
is maintained in response to environmental stresses. Due to their unique chemical
properties, transition metals such as copper, iron, and zinc are critical cofactors
in the active sites of enzymes and as structural components in proteins. However,
many of these essential metals are toxic when present in excess, indicating a requirement
for the cell to maintain a fairly narrow intracellular concentration of each metal.
In addition, metal metabolism may be altered by environmental stress through multiple
mechanisms. Cells can adjust transport and storage of the metal in response to the
stress, either through increased uptake, efflux, or expression of metal storage proteins.
The metal or metal cofactor may be directly modified, for instance by oxidation or
reduction, leading to a subsequent change in reactivity, ligand affinity, or bioavailability.
Conversely, the proteins or other biomolecules that interact with the metal or metal
cofactor may themselves be altered by the stress, causing a change in metal metabolism
such as release of metal from an active site. Defining the biochemical strategies
used by organisms to maintain metal homeostasis under stress will provide insight
into critical areas ranging from bacterial pathogenesis to human disease.
The Suf pathway and Fe-S cluster assembly under stress: Fe-S clusters, which contain
inorganic sulfur and iron, play key roles in electron transport, as active site cofactors
in TCA cycle enzymes, and as exquisite sensors of oxygen and oxygen radicals in stress-responsive
transcription factors. However, Fe-S clusters are perturbed by multiple stress conditions.
During oxidative stress, superoxide anion (O2•-) can damage [4Fe-4S] clusters leading
to cluster degradation and release of iron. Therefore, Fe-S clusters are assembled
in vivo via intricate biosynthetic pathways. The Fe-S cluster assembly pathway encoded
by the sufABCDSE operon is required to assemble Fe-S clusters during iron starvation
or oxidative stress, conditions known to disrupt Fe-S clusters in vivo. To determine
the biochemical mechanisms used by the Suf pathway to achieve this feat, we have purified
all six of the suf-encoded proteins. We have found that SufB, SufC and SufD, co-purify
as a stable complex. This three-protein complex interacts with the SufE protein to
dramatically enhance sulfur donation by the SufS cysteine desulfurase enzyme. SufE
acts as a sulfur transfer partner and together with the SufBCD complex, which comprises
a novel sulfur transfer pathway for Fe-S cluster assembly under stress conditions.
Further genetic, regulatory, and biochemical analysis will elucidate how the Suf proteins
are adapted to acquire iron and sulfur for construction of Fe-S clusters during iron
starvation and oxidative stress. This research focus is currently funded by the National
Institutes of Health (NIH).
Integration of metal homeostasis with cellular metabolism
Transition metal homeostasis is a key process for all forms of life. Metal homeostasis
can be disrupted by a variety of environmental or genetic factors. For example, oxygen
can alter the oxidation state of some transition metals, such as iron and copper,
thereby altering their bioavailability and toxicity. In addition, the requirement
for multiple transition metals for correct cell function can be problematic if some
transition metals compete with each other for binding to similar protein active sites.
Iron is critical for growth due to the need for iron in cofactors like heme and iron-sulfur
(Fe-S) clusters. However, iron has limited bioavailability in the environment and
iron homeostasis is disrupted by oxidative stress. Iron can also be disrupted by excess
levels of other metals, such as cobalt and copper, that compete with iron for incorporation
into Fe-S clusters. Metals such as copper and iron play critical roles as cofactors
in multiple metabolic pathways, including the tricarboxylic acid cycle (Krebs cycle),
respiration, amino acid biosynthesis, and isoprenoid biosynthesis. Therefore, cellular
metabolism is highly responsive to and integrated with metal homeostasis. We are
specifically interested in how Fe-S cluster biogenesis and iron homeostasis are integrated
with cell membrane biogenesis in E. coli, through such processes as protein-protein
interaction networks, transcriptional regulation, and metalloenzyme maturation. Early
results indicate that the monothiol glutaredoxin, GrxD may work in concert with BolA
and IbaG morphoproteins to coordinate Fe-S cluster trafficking with membrane biogenesis.
This research focus is currently funded by the National Science Foundation (NSF).
Selected Publications
Kim, D., Singh, H., Dai, Y., Dong, G., Busenlehner, L.S., Outten, F.W., Frantom, P.A. (2018) Changes in protein dynamics in Escherichia coli SufS reveal a possible conserved regulatory mechanism in Type II Cysteine Desulfurase systems. Biochemistry. 57(35): 5210 – 5217. https://doi.org/10.1021/acs.biochem.7b01275
Washington – Hughes, C.L., Ford, G.T., Jones, A.D., McRae, K., Outten, F.W. (2019) Nickel exposure reduces enterobactin production in Escherichia coli. MicrobiologyOpen.
8(4): e00691. https://doi.org/10.1002/mbo3.691
Dunkle, J.A., Bruno, M., Outten, F.W., Frantom, P.A. (2019) Structural evidence for dimer – interface driven regulation of the type II cysteine
desulfurase, SufS. Biochemistry. 58(6): 687 – 696. https://doi.org/10.1021/acs.biochem.8b01122
Wofford, J.D., Bolaji, N., Dziuba, N., Outten, F.W., Lindahl, P.A. (2019) Evidence that a respiratory shield in Escherichia coli protects a low – molecular
– mass Fe(II) pool from O2 – dependent oxidation. J Biol Chem. 294(1): 50 – 62. https://doi.org/10.1074/jbc.ra118.005233
Blahut, M., Wise, C.E., Bruno, M.R., Dong, G., Makris, T.M., Frantom P.A., Dunkle, J.A., Outten, F.W. (2019) Direct observation of intermediates in the SufS cysteine desulfurase reaction reveals functional roles of conserved active – site residues. J Biol Chem. 294(33): 12444 – 12458. https://doi.org/10.1074/jbc.RA119.009471