TY - JOUR
T1 - Substrate-Triggered Formation of a Peroxo-Fe2(III/III) Intermediate during Fatty Acid Decarboxylation by UndA
AU - Zhang, Bo
AU - Rajakovich, Lauren J.
AU - Van Cura, Devon
AU - Blaesi, Elizabeth J.
AU - Mitchell, Andrew J.
AU - Tysoe, Christina R.
AU - Zhu, Xuejun
AU - Streit, Bennett R.
AU - Rui, Zhe
AU - Zhang, Wenjun
AU - Boal, Amie K.
AU - Krebs, Carsten
AU - Bollinger, J. Martin
N1 - Funding Information:
This work was supported by the National Science Foundation (CHE-1610676 to C.K., J.M.B., and A.K.B.) and the National Institutes of Health (National Research Service Awards GM- 116353 to E.J.B. and GM-103220 to B.R.S.). Portions of this work were conducted at the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences. Portions of this work were conducted at the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DEAC02- 06CH11357. GM/CA at APS has been funded in whole or in part with Federal funds from the National Cancer Institute (ACB-12002) and the National Institute of General Medical Sciences (AGM-12006). Use of LS-CAT Sector 21 was supported by the Michigan Economic Development Corporation and the Michigan Technology Tri-Corridor Grant (085P1000817). We thank Dr. Christopher J. Pollock for helpful discussions regarding EXAFS data collection and analysis.
Funding Information:
This work was supported by the National Science Foundation (CHE-1610676 to C.K., J.M.B., and A.K.B.) and the National Institutes of Health (National Research Service Awards GM-116353 to E.J.B. and GM-103220 to B.R.S.). Portions of this work were conducted at the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences. Portions of this work were conducted at the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. GM/CA at APS has been funded in whole or in part with Federal funds from the National Cancer Institute (ACB-12002) and the National Institute of General Medical Sciences (AGM-12006). Use of LS-CAT Sector 21 was supported by the Michigan Economic Development Corporation and the Michigan Technology Tri-Corridor Grant (085P1000817). We thank Dr. Christopher J. Pollock for helpful discussions regarding EXAFS data collection and analysis.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/9/18
Y1 - 2019/9/18
N2 - The iron-dependent oxidase UndA cleaves one C3-H bond and the C1-C2 bond of dodecanoic acid to produce 1-undecene and CO2. A published X-ray crystal structure showed that UndA has a heme-oxygenase-like fold, thus associating it with a structural superfamily that includes known and postulated non-heme diiron proteins, but revealed only a single iron ion in the active site. Mechanisms proposed for initiation of decarboxylation by cleavage of the C3-H bond using a monoiron cofactor to activate O2 necessarily invoked unusual or potentially unfeasible steps. Here we present spectroscopic, crystallographic, and biochemical evidence that the cofactor of Pseudomonas fluorescens Pf-5 UndA is actually a diiron cluster and show that binding of the substrate triggers rapid addition of O2 to the Fe2(II/II) cofactor to produce a transient peroxo-Fe2(III/III) intermediate. The observations of a diiron cofactor and substrate-triggered formation of a peroxo-Fe2(III/III) intermediate suggest a small set of possible mechanisms for O2, C3-H and C1-C2 activation by UndA; these routes obviate the problematic steps of the earlier hypotheses that invoked a single iron.
AB - The iron-dependent oxidase UndA cleaves one C3-H bond and the C1-C2 bond of dodecanoic acid to produce 1-undecene and CO2. A published X-ray crystal structure showed that UndA has a heme-oxygenase-like fold, thus associating it with a structural superfamily that includes known and postulated non-heme diiron proteins, but revealed only a single iron ion in the active site. Mechanisms proposed for initiation of decarboxylation by cleavage of the C3-H bond using a monoiron cofactor to activate O2 necessarily invoked unusual or potentially unfeasible steps. Here we present spectroscopic, crystallographic, and biochemical evidence that the cofactor of Pseudomonas fluorescens Pf-5 UndA is actually a diiron cluster and show that binding of the substrate triggers rapid addition of O2 to the Fe2(II/II) cofactor to produce a transient peroxo-Fe2(III/III) intermediate. The observations of a diiron cofactor and substrate-triggered formation of a peroxo-Fe2(III/III) intermediate suggest a small set of possible mechanisms for O2, C3-H and C1-C2 activation by UndA; these routes obviate the problematic steps of the earlier hypotheses that invoked a single iron.
UR - http://www.scopus.com/inward/record.url?scp=85072369689&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85072369689&partnerID=8YFLogxK
U2 - 10.1021/jacs.9b06093
DO - 10.1021/jacs.9b06093
M3 - Article
C2 - 31487162
AN - SCOPUS:85072369689
SN - 0002-7863
VL - 141
SP - 14510
EP - 14514
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 37
ER -