title: Electrochemical characterization of Escherichia coli adaptive response protein AidB.
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.
authors: Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA. elliott@bu.edu.
authors: Michael J
authors: MJ
authors: Hamill
authors: Marco
authors: M
authors: Jost
authors: Cintyu
authors: C
authors: Wong
authors: Nicholas C
authors: NC
authors: Bene
authors: Catherine L
authors: CL
authors: Drennan
authors: Sean J
authors: SJ
authors: Elliott
mesh_terms: D004260:DNA Repair; D055664:Electrochemical Techniques; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics
chemical_list: C090096:AidB protein, E coli; D029968:Escherichia coli Proteins; D005182:Flavin-Adenine Dinucleotide