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Astacidin

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Astacidin is an antimicrobial peptide produced by Procambarus clarkii (freshwater crayfish Pacifastacus leniusculus). It encodes a peptide of 43 amino acids, with a signal peptide of 23 amino acids. The mature peptide contains 20 amino acids, among which four are proline/arginine amino acids. The synthetic mature peptide has inhibitory effects on both Gram-positive and gram-negative bacteria and has the ability to bind bacterial cell wall components, including peptidoglycan, lipopolysaccharide and lipophoteicic acid.

Category
Functional Peptides
Catalog number
BAT-013037
Synonyms
PcAst; Met-Arg-Leu-Leu-His-Leu-Leu-Leu-Ser-Val-Ala-Leu-Val-Ala-Leu-Met-Ala-Ala-Val-Pro-Ser-Gln-Ala-Ser-Asn-Gly-Tyr-Arg-Pro-Ala-Tyr-Arg-Pro-Ala-Tyr-Arg-Pro-Ser-Tyr-Arg-Pro-Gly-Lys
Purity
>98%
Sequence
MRLLHLLLSVALVALMAAVPSQASNGYRPAYRPAYRPSYRPGK
1. Identification and functional characterization of the astacidin family of proline-rich host defence peptides (PcAst) from the red swamp crayfish (Procambarus clarkii, Girard 1852)
Tomislav Rončević, et al. Dev Comp Immunol. 2020 Apr;105:103574. doi: 10.1016/j.dci.2019.103574. Epub 2019 Dec 13.
This study reports the identification of four novel proline-rich antimicrobial peptides (PR-AMP) from the transcriptome of the red swamp crayfish Procambarus clarkii. The newly identified putative peptides (PcAst-1b, -1c, -2 and -3), which are related with the previously identified hemocyte-specific PR-AMP astacidin-1, are encoded by the multi-genic astacidin gene family. The screening of available and proprietary transcriptomes allowed to define the taxonomical range of distribution of this gene family to Astacoidea and Parastacoidea. The antimicrobial properties of three synthetic PcAst peptides (PcAst-1a, -1b/c and -2), were characterized against reference bacteria or multidrug resistant clinical isolates, and their cytotoxicity was evaluated towards human transformed cell lines. The antimicrobial activity ranged from potent and broad-spectrum, in low-salt medium, to poor, whereas it was generally low in full nutrient broth. No significant toxic effects were observed on cultured human cells. RNA-seq data from 12 different tissues indicated a strong specificity for haemocytes under naïve physiological condition, with moderate expression (5-fold lower) in gills. Quantitative real time PCR revealed a rapid (within 2 h) and significant up-regulation of PcAst-1a (Astacidin 1) and PcAst-2 expression in response to LPS injection. Due to the variation in antimicrobial potency and inducibility, the roles of the other astacidins (PcAst-1b, -1c and -3) need to be further investigated to determine their significance to the immune responses of the red swamp crayfish.
2. Processing of an antibacterial peptide from hemocyanin of the freshwater crayfish Pacifastacus leniusculus
So Young Lee, Bok Luel Lee, Kenneth Söderhäll J Biol Chem. 2003 Mar 7;278(10):7927-33. doi: 10.1074/jbc.M209239200. Epub 2002 Dec 18.
An antibacterial peptide with 16 amino acid residues was found in plasma of the freshwater crayfish, Pacifastacus leniusculus. This peptide, designated astacidin 1, was purified by cation-exchange column chromatography and reverse-phase high performance liquid chromatography. Astacidin 1 has a broad range of antibacterial activity, and it inhibits growth of both Gram-positive and Gram-negative bacteria. The primary sequence of astacidin 1 was FKVQNQHGQVVKIFHH-COOH. The molecular mass was 1945.2 Da, and no carbohydrate-linked amino acid residues could be found by mass spectrometry. A synthetic astacidin 1 resulted in similar activity as the authentic astacidin 1 against Gram-positive bacteria, whereas it had less or no activity against Gram-negative bacteria. Three amino-terminal-truncated synthetic peptides were made; they all showed low activity, suggesting that the amino-terminal part of astacidin 1 contributes to the antibacterial activity. The structure of astacidin 1 based on the CD results showed that it has a beta-sheet structure in citric acid buffer at pH 4, 6, and 8. Cloning of astacidin 1 shows that it is the carboxyl-terminal part of crayfish hemocyanin and that astacidin 1 is produced by a proteolytic cleavage from hemocyanin under acidic conditions. The processing and release of astacidin 1 from hemocyanin is enhanced when crayfish are injected with lipopolysaccharide or glucan.
3. Antifungal activity and pore-forming mechanism of astacidin 1 against Candida albicans
Hyemin Choi, Dong Gun Lee Biochimie. 2014 Oct;105:58-63. doi: 10.1016/j.biochi.2014.06.014. Epub 2014 Jun 21.
In a previous report, a novel antibacterial peptide astacidin 1 (FKVQNQHGQVVKIFHH) was isolated from hemocyanin of the freshwater crayfish Pacifastacus leniusculus. In this study, the antifungal activity and mechanism of astacidin 1 were evaluated. Astacidin 1 exhibited antifungal activity against Candida albicans, Trichosporon beigelii, Malassezia furfur, and Trichophyton rubrum. Also, astacidin 1 had fungal cell selectivity in human erythrocytes without causing hemolysis. To understand the antifungal mechanism, membrane studies were done against C. albicans and T. beigelii. Flow cytometric analysis and K(+) measurement showed membrane damage, resulting in membrane permeabilization and K(+) release-induced membrane depolarization. Furthermore, the calcein leakage from liposomes mimicking C. albicans membrane demonstrated that the membrane-active action was driven by pore-forming mechanism. Live cell imaging using fluorescein isothiocyanate-labeled dextrans of various sizes suggested that the radii of pores formed in the C. albicans membrane were 1.4-2.3 nm. Therefore, the present study suggests that astacidin 1 exerts its antifungal effect by damaging the fungal membrane via pore formation.
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