title: Polyamines: naturally occurring small molecule modulators of electrostatic protein-protein interactions.
abstract: Modulations of protein-protein interactions are a key step in regulating protein function, especially in networks. Modulators of these interactions are supposed to be candidates for the development of novel drugs. Here, we describe the role of the small, polycationic and highly abundant natural polyamines that could efficiently bind to charged spots at protein interfaces as modulators of such protein-protein interactions. Using the mitochondrial cytochrome P45011A1 (CYP11A1) electron transfer system as a model, we have analyzed the capability of putrescine, spermidine, and spermine at physiologically relevant concentrations to affect the protein-protein interactions between adrenodoxin reductase (AdR), adrenodoxin (Adx), and CYP11A1. The actions of polyamines on the individual components, on their association/dissociation, on electron transfer, and on substrate conversion were examined. These studies revealed modulating effects of polyamines on distinct interactions and on the entire system in a complex way. Modulation via changed protein-protein interactions appeared plausible from docking experiments that suggested favourable high-affinity binding sites of polyamines (spermine>spermidine>putrescine) at the AdR-Adx interface. Our findings imply for the first time that small endogenous compounds are capable of interfering with distinct components of transient protein complexes and might control protein functions by modulating electrostatic protein-protein interactions.
authors.affiliation: Institute of Biochemistry, Saarland University, D-66041 Saarbrücken, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Berwanger
authors.forename: Susanne
authors.initials: S
authors.lastname: Eyrisch
authors.forename: Inge
authors.initials: I
authors.lastname: Schuster
authors.forename: Volkhard
authors.initials: V
authors.lastname: Helms
authors.forename: Rita
authors.initials: R
authors.lastname: Bernhardt
mesh_terms: D000325:Adrenodoxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D002384:Catalysis / Q000187:drug effects; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation; D010084:Oxidation-Reduction / Q000187:drug effects; D011073:Polyamines / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D011700:Putrescine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013095:Spermidine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013096:Spermine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D055672:Static Electricity
chemical_list: D011073:Polyamines; D011506:Proteins; D000325:Adrenodoxin; D013096:Spermine; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase; D013095:Spermidine; D011700:Putrescine