title: An immune-responsive Serpin regulates the melanization cascade in Drosophila.
abstract: In arthropods, the melanization reaction is associated with multiple host defense mechanisms leading to the sequestration and killing of invading microorganisms. Arthropod melanization is controlled by a cascade of serine proteases that ultimately activates the enzyme prophenoloxidase (PPO), which, in turn, catalyzes the synthesis of melanin. Here we report the biochemical and genetic characterization of a Drosophila serine protease inhibitor protein, Serpin-27A, which regulates the melanization cascade through the specific inhibition of the terminal protease prophenoloxidase-activating enzyme. Our data demonstrate that Serpin-27A is required to restrict the phenoloxidase activity to the site of injury or infection, preventing the insect from excessive melanization.
authors.affiliation: Centre de Génétique Moléculaire du CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Ennio
authors.initials: E
authors.lastname: De Gregorio
authors.forename: Sung-Jun
authors.initials: SJ
authors.lastname: Han
authors.forename: Won-Jae
authors.initials: WJ
authors.lastname: Lee
authors.forename: Min-Ji
authors.initials: MJ
authors.lastname: Baek
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Osaki
authors.forename: Shun-Ichiro
authors.initials: S
authors.lastname: Kawabata
authors.forename: Bok-Leul
authors.initials: BL
authors.lastname: Lee
authors.forename: Sadaaki
authors.initials: S
authors.lastname: Iwanaga
authors.forename: Bruno
authors.initials: B
authors.lastname: Lemaitre
authors.forename: Paul T
authors.initials: PT
authors.lastname: Brey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004156:Catechol Oxidase / Q000276:immunology / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000276:immunology*; D004792:Enzyme Precursors / Q000276:immunology / Q000378:metabolism; D008543:Melanins / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D015843:Serpins / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology
chemical_list: D029721:Drosophila Proteins; D004792:Enzyme Precursors; D008543:Melanins; D015843:Serpins; C468118:Spn27A protein, Drosophila; C038451:pro-phenoloxidase; D004156:Catechol Oxidase