cDNA cloning of halocidin and a new antimicrobial peptide derived from the N-terminus of Ci-META4.
Halocidin is an antimicrobial peptide, which is isolated from hemocytes from the tunicate, Halocynthiaaurantium. In this study, we cloned the full-length cDNA of halocidin from pharyngeal tissue, using a combination of RT-PCR and 5'-RACE-PCR. The observed cDNA structure indicated that halocidin is synthesized as a 10.37 kDa prepropeptide. Based on the cDNA structure and the known amino acid sequence of the mature peptide, it was concluded that the precursor of halocidin contains a 21-residue signal peptide, followed by the 18 residues of the mature peptide, and a 56-residue anionic C-terminal extension, which is removed later on in the process. The signal sequence of halocidin exhibited a high degree of similarity with the corresponding portion of the Ci-META4 protein, which had been previously discovered in the coelomic cells of another tunicate, Cionaintestinalis, and is considered to play a role in metamorphosis. However, in several respects, the cDNA structure of Ci-META4 suggested that it might constitute a precursor for an antimicrobial peptide. Thus, we prepared a synthetic peptide, which was comprised of 19 N-terminal amino acid residues in the predicted mature region of Ci-META4, and tested it with regard to its antimicrobial activity. As a result, we confirmed that the synthetic peptide exhibited potent antimicrobial activity against Gram (+) and (-) bacteria, while evidencing no hemolytic activity toward human erythrocytes.
Jang
Woong Sik
WS
Department of Bio-Technology, Hoseo University, Asan City, Chungnam-Do 336-795, South Korea.
Kim
Chong Han
CH
Kang
Min Sook
MS
Chae
Hee Jeong
HJ
Son
Seok Min
SM
Seo
Sook Jae
SJ
Lee
In Hee
IH
D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D001419:Bacteria / Q000254:growth & development; D001483:Base Sequence; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D014561:Urochordata / Q000737:chemistry / Q000235:genetics*
D000890:Anti-Infective Agents; D010455:Peptides; C460842:halocidin