title: Structural evidence for lack of inhibition of fish goose-type lysozymes by a bacterial inhibitor of lysozyme.
abstract: It is known that bacteria contain inhibitors of lysozyme activity. The recently discovered Escherichia coli inhibitor of vertebrate lysozyme (Ivy) and its potential interactions with several goose-type (g-type) lysozymes from fish were studied using functional enzyme assays, comparative homology modelling, protein-protein docking, and molecular dynamics simulations. Enzyme assays carried out on salmon g-type lysozyme revealed a lack of inhibition by Ivy. Detailed analysis of the complexes formed between Ivy and both hen egg white lysozyme (HEWL) and goose egg white lysozyme (GEWL) suggests that electrostatic interactions make a dominant contribution to inhibition. Comparison of three dimensional models of aquatic g-type lysozymes revealed important insertions in the beta domain, and specific sequence substitutions yielding altered electrostatic surface properties and surface curvature at the protein-protein interface. Thus, based on structural homology models, we propose that Ivy is not effective against any of the known fish g-type lysozymes. Docking studies suggest a weaker binding mode between Ivy and GEWL compared to that with HEWL, and our models explain the mechanistic necessity for conservation of a set of residues in g-type lysozymes as a prerequisite for inhibition by Ivy.
authors.affiliation: Marine Biotechnology and Fish Health, Norwegian Institute of Fisheries and Aquaculture, PO Box 6122, 9291 Tromsø, Norway.
authors.forename: Peter
authors.initials: P
authors.lastname: Kyomuhendo
authors.forename: Inge W
authors.initials: IW
authors.lastname: Nilsen
authors.forename: Bjørn Olav
authors.initials: BO
authors.lastname: Brandsdal
authors.forename: Arne O
authors.initials: AO
authors.lastname: Smalås
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D003198:Computer Simulation; D003461:Crystallography; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D020224:Expressed Sequence Tags; D005399:Fishes; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009113:Muramidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000145:classification*; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C429555:Ivy protein, E coli; D014867:Water; D009113:Muramidase