title: Specific DNA binding and regulation of its own expression by the AidB protein in Escherichia coli.
abstract: Upon exposure to alkylating agents, Escherichia coli increases expression of aidB along with three genes (ada, alkA, and alkB) that encode DNA repair proteins. While the biological roles of the Ada, AlkA, and AlkB proteins have been defined, despite many efforts, the molecular functions of AidB remain largely unknown. In this study, we focused on the biological role of the AidB protein, and we demonstrated that AidB shows preferential binding to a DNA region that includes the upstream element of its own promoter, PaidB. The physiological significance of this specific interaction was investigated by in vivo gene expression assays, demonstrating that AidB can repress its own synthesis during normal cell growth. We also showed that the domain architecture of AidB is related to the different functions of the protein: the N-terminal region, comprising the first 439 amino acids (AidB "I-III"), possesses FAD-dependent dehydrogenase activity, while its C-terminal domain, corresponding to residues 440 to 541 (AidB "IV"), displays DNA binding activity and can negatively regulate the expression of its own gene in vivo. Our results define a novel role in gene regulation for the AidB protein and underline its multifunctional nature.
authors.affiliation: Department of Organic Chemistry and Biochemistry, University Federico II of Naples, Naples, Italy,
authors.forename: Valentina
authors.initials: V
authors.lastname: Rippa
authors.forename: Angela
authors.initials: A
authors.lastname: Amoresano
authors.forename: Carla
authors.initials: C
authors.lastname: Esposito
authors.forename: Paolo
authors.initials: P
authors.lastname: Landini
authors.forename: Michael
authors.initials: M
authors.lastname: Volkert
authors.forename: Angela
authors.initials: A
authors.lastname: Duilio
mesh_terms: D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D050436:Regulatory Elements, Transcriptional; D012097:Repressor Proteins / Q000378:metabolism
chemical_list: C090096:AidB protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012097:Repressor Proteins