RESUMEN
We identified and characterized the activity of prolixicin, a novel antimicrobial peptide (AMP) isolated from the hemipteran insect, Rhodnius prolixus. Sequence analysis reveals one region of prolixicin that may be related to the diptericin/attacin family of AMPs. Prolixicin is an 11-kDa peptide containing a putative 21 amino acid signal peptide, two putative phosphorylation sites and no glycosylation sites. It is produced by both adult fat body and midgut tissues in response to bacterial infection of the haemolymph or the midgut. Unlike most insect antibacterial peptides, the prolixicin gene does not seem to be regulated by NF-κB binding sites, but its promoter region contains several GATA sites. Recombinant prolixicin has strong activity against the Gram-negative bacterium Escherichia coli and differential activity against several Gram-negative and Gram-positive bacteria. No significant toxicity was demonstrated against Trypanosoma cruzi, the human parasite transmitted by R. prolixus.
Asunto(s)
Péptidos Catiónicos Antimicrobianos/inmunología , Rhodnius/inmunología , Secuencia de Aminoácidos , Animales , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/genética , Péptidos Catiónicos Antimicrobianos/aislamiento & purificación , Bacterias/inmunología , Secuencia de Bases , Etiquetas de Secuencia Expresada , Perfilación de la Expresión Génica , Datos de Secuencia Molecular , Filogenia , Regiones Promotoras Genéticas , Proteínas Recombinantes/inmunología , Rhodnius/química , Rhodnius/genética , Trypanosoma cruzi/inmunologíaRESUMEN
Rhodnius prolixus is an ancient haematophagous hemipteran insect capable of mounting a powerful immune response. This response is transcriptionally regulated in part by transcription factors of the Rel/Nuclear Factor kappa B (Rel/NF-kappaB) family. We have cloned and characterized three members of this transcription factor family in this insect. Dorsal 1A is primarily expressed in early developmental stages. In contrast, dorsal 1B and 1C, both differentially spliced products of dorsal 1A, are expressed primarily in the adult fat body in response to septic injury, suggesting their exclusive role in immunity. Additionally, we identified putative kappaB binding sites in the 5' upstream regions of target genes known to be involved in the innate immune response of insects.
Asunto(s)
Proteínas de Drosophila/química , Proteínas de Insectos/genética , Proteínas Nucleares/química , Fosfoproteínas/química , Rhodnius/genética , Homología de Secuencia de Aminoácido , Factores de Transcripción/química , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Sitios de Unión , Clonación Molecular , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Genes de Insecto , Proteínas de Insectos/química , Datos de Secuencia Molecular , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Recombinantes/metabolismo , Análisis de Secuencia de Proteína , Factores de Transcripción/metabolismoRESUMEN
Lysozymes are enzymes characterized by their ability to break down bacterial cell walls. In insects certain lysozymes are only found in the midgut, whereas others are only found in the haemolymph and fat body after immune challenge. We identified two lysozyme-encoding cDNAs from Aedes aegypti. Both deduced protein sequences are basic in nature, contain 148 amino acids including eight highly conserved cysteine residues, and their genomic sequences contain a single intron. Transcriptional profiles indicated that the predominant form is constitutively expressed and up-regulated upon immune challenge and blood feeding in adult mosquitoes. The second form is expressed during early developmental stages, larvae and pupae, and at low levels in adults after immune challenge. Lysozymes in Aedes aegypti play both roles, defined by the spatial and temporal regulation of their expression.