title: Functional divergence in shrimp anti-lipopolysaccharide factors (ALFs): from recognition of cell wall components to antimicrobial activity.
abstract: Antilipopolysaccharide factors (ALFs) have been described as highly cationic polypeptides with a broad spectrum of potent antimicrobial activities. In addition, ALFs have been shown to recognize LPS, a major component of the Gram-negative bacteria cell wall, through conserved amino acid residues exposed in the four-stranded β-sheet of their three dimensional structure. In penaeid shrimp, ALFs form a diverse family of antimicrobial peptides composed by three main variants, classified as ALF Groups A to C. Here, we identified a novel group of ALFs in shrimp (Group D ALFs), which corresponds to anionic polypeptides in which many residues of the LPS binding site are lacking. Both Group B (cationic) and Group D (anionic) shrimp ALFs were produced in a heterologous expression system. Group D ALFs were found to have impaired LPS-binding activities and only limited antimicrobial activity compared to Group B ALFs. Interestingly, all four ALF groups were shown to be simultaneously expressed in an individual shrimp and to follow different patterns of gene expression in response to a microbial infection. Group B was by far the more expressed of the ALF genes. From our results, nucleotide sequence variations in shrimp ALFs result in functional divergence, with significant differences in LPS-binding and antimicrobial activities. To our knowledge, this is the first functional characterization of the sequence diversity found in the ALF family.
authors.affiliation: Ecologie des Systèmes Marins Côtiers, UMR5119, Centre National de la Recherche Scientifique, Institut de la Recherche pour le Développement, Université Montpellier 1, Montpellier, France.
authors.forename: Rafael Diego
authors.initials: RD
authors.lastname: Rosa
authors.forename: Agnès
authors.initials: A
authors.lastname: Vergnes
authors.forename: Julien
authors.initials: J
authors.lastname: de Lorgeril
authors.forename: Priscila
authors.initials: P
authors.lastname: Goncalves
authors.forename: Luciane Maria
authors.initials: LM
authors.lastname: Perazzolo
authors.forename: Laure
authors.initials: L
authors.lastname: Sauné
authors.forename: Bernard
authors.initials: B
authors.lastname: Romestand
authors.forename: Julie
authors.initials: J
authors.lastname: Fievet
authors.forename: Yannick
authors.initials: Y
authors.lastname: Gueguen
authors.forename: Evelyne
authors.initials: E
authors.lastname: Bachère
authors.forename: Delphine
authors.initials: D
authors.lastname: Destoumieux-Garzón
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D002473:Cell Wall / Q000737:chemistry; D005658:Fungi / Q000187:drug effects / Q000254:growth & development; D015870:Gene Expression; D014644:Genetic Variation; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000254:growth & development; D006434:Hemocytes / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D033561:Penaeidae / Q000235:genetics* / Q000276:immunology; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D011994:Recombinant Proteins