title: Two novel non-cationic defensin-like antimicrobial peptides from haemolymph of the female tick, Amblyomma hebraeum.
abstract: Two non-cationic defensin-like antimicrobial peptides, named Amblyomma defensin peptide 1 and Amblyomma defensin peptide 2, were identified from the hard tick, Amblyomma hebraeum, by a combination of suppression subtractive hybridization for differentially expressed genes and proteomics. cDNA clones encoding each of these two defensin-like antimicrobial peptides were isolated from the differentially expressed cDNA library of the tick synganglia (central nervous system). The preproproteins deduced from the cDNA sequences each have 92 amino acid residues. Amblyomma defensin peptide 2 was purified from the haemolymph of fed female ticks. The purified peptide displayed antibacterial activity against Gram-negative and Gram-positive bacteria. Amblyomma defensin peptide 1 was further identified by protein chip capture combined with SELDI-TOF (surface-enhanced laser desorption/ionization-time-of-flight) MS. By screening for differentially expressed proteins, it was found that the expression of Amblyomma defensin peptide 1 was upregulated during 4 days post-feeding. Our findings firstly provide two defensin-like antimicrobial peptides that are particularly novel in being anionic, together with corresponding cDNA sequences, in hard ticks, and prove that the combination of suppression subtractive hybridization and protein profiling is a powerful method to study differentially expressed proteins, especially for organisms without available genome sequence information.
authors.affiliation: Cellular Regulation and Signalling Division, School of Biological Sciences, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK.
authors.forename: Ren
authors.initials: R
authors.lastname: Lai
authors.forename: Lee O
authors.initials: LO
authors.lastname: Lomas
authors.forename: Jan
authors.initials: J
authors.lastname: Jonczy
authors.forename: Philip C
authors.initials: PC
authors.lastname: Turner
authors.forename: Huw H
authors.initials: HH
authors.lastname: Rees
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D023082:Defensins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015723:Gene Library; D006458:Hemolymph / Q000737:chemistry*; D026863:Ixodidae / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D040081:Protein Array Analysis; D020539:Sequence Analysis, Protein; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D023082:Defensins