title: Unique complex between bacterial azurin and tumor-suppressor protein p53.
abstract: The tumor-suppressor protein p53 is a major player in regulation of cell growth, genomic stability, and cell death. Recent work suggests that Pseudomonas aeruginosa azurin, as the only bacterial protein known to date, can enter cancer cells and interact with p53 promoting cell death. For the first time, here we demonstrate and characterize this proposed complex using purified proteins in vitro. We find that azurin binds to p53 with nanomolar affinity in a four-to-one stoichiometry (pH 7.5, 25 degrees C). Upon azurin binding, secondary structure is induced and tryptophan fluorescence is quenched, implying that interactions occur in the N-terminal p53 domain which is also the binding site for many oncogenes. Further biophysical studies may assist the design of novel cancer treatments that are based on azurin.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, Houston, TX 77251, USA.
authors.forename: David
authors.initials: D
authors.lastname: Apiyo
authors.forename: Pernilla
authors.initials: P
authors.lastname: Wittung-Stafshede
mesh_terms: D001400:Azurin / Q000737:chemistry*; D001665:Binding Sites; D001703:Biophysics / Q000379:methods; D002151:Calorimetry; D002850:Chromatography, Gel; D002942:Circular Dichroism; D006801:Humans; D007700:Kinetics; D010084:Oxidation-Reduction; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics; D014364:Tryptophan / Q000737:chemistry; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry*
chemical_list: D016159:Tumor Suppressor Protein p53; D001400:Azurin; D014364:Tryptophan