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Electrochemical Characterization of Escherichia coli Adaptive Response Protein AidB
Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA
Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Center for Environmental Health, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Present address: Johnson & Johnson Pharmaceutical Research & Development, 930 Route 202 South, Raritan, NJ 08869, USA
* Author to whom correspondence should be addressed.
Received: 7 October 2012; in revised form: 26 November 2012 / Accepted: 3 December 2012 / Published: 11 December 2012
(This article belongs to the Special Issue Flavins
Abstract: When exposed to known DNA-damaging alkylating agents, Escherichia coli cells increase production of four DNA repair enzymes: Ada, AlkA, AlkB, and AidB. The role of three enzymes (Ada, AlkA, and AlkB) in repairing DNA lesions has been well characterized, while the function of AidB is poorly understood. AidB has a distinct cofactor that is potentially related to the elusive role of AidB in adaptive response: a redox active flavin adenine dinucleotide (FAD). In this study, we report the thermodynamic redox properties of the AidB flavin for the first time, both for free protein and in the presence of potential substrates. We find that the midpoint reduction potential of the AidB flavin is within a biologically relevant window for redox chemistry at −181 mV, that AidB significantly stabilizes the flavin semiquinone, and that small molecule binding perturbs the observed reduction potential. Our electrochemical results combined with structural analysis allow for fresh comparisons between AidB and the homologous acyl-coenzyme A dehydrogenase (ACAD) family of enzymes. AidB exhibits several discrepancies from ACADs that suggest a novel catalytic mechanism distinct from that of the ACAD family enzymes.
Keywords: adaptive response; DNA repair; protein electrochemistry; acyl-coenzyme A dehydrogenase; flavin cofactor; reduction potential
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MDPI and ACS Style
Hamill, M.J.; Jost, M.; Wong, C.; Bene, N.C.; Drennan, C.L.; Elliott, S.J. Electrochemical Characterization of Escherichia coli Adaptive Response Protein AidB. Int. J. Mol. Sci. 2012, 13, 16899-16915.
Hamill MJ, Jost M, Wong C, Bene NC, Drennan CL, Elliott SJ. Electrochemical Characterization of Escherichia coli Adaptive Response Protein AidB. International Journal of Molecular Sciences. 2012; 13(12):16899-16915.
Hamill, Michael J.; Jost, Marco; Wong, Cintyu; Bene, Nicholas C.; Drennan, Catherine L.; Elliott, Sean J. 2012. "Electrochemical Characterization of Escherichia coli Adaptive Response Protein AidB." Int. J. Mol. Sci. 13, no. 12: 16899-16915.