Defensins. Natural peptide antibiotics of human neutrophils.

Ganz, Tomas; Selsted, Michael E.; Szklarek, D; Harwig, Sylvia S.L.; Daher, Kathleen A.; Bainton, Dorothy F.; Lehrer, Robert I.

doi:10.1172/jci112120

Cited by 1,302 publications

(997 citation statements)

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“…29-34 amino acid residues long (M, = 3,500-4,000) and have been found in rats (Eisenhauer et al, 1989), rabbits , and guinea pigs (Selsted & Harwig, 1987), as well as humans (Ganz et al, 1985;Selsted et al, 1985b;Wilde et al, 1989). The amino acid sequences of the defensins have been determined and when they are aligned (Table 1) to emphasize the positions of the conserved residues, a family of cationic peptides is revealed whose net charge varies from +2 for defensin HNP-3 to +9 for defensin NP-1.…”

Section: ~~ ~ ~~~~mentioning

confidence: 99%

Defensins promote fusion and lysis of negatively charged membranes

Fujii

Selsted

Eisenberg³

1993

Protein Science

155

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Defensins, a family of cationic peptides isolated from mammalian granulocytes and believed to permeabilize membranes, were tested for their ability to cause fusion and lysis of liposomes. Unlike a-helical peptides whose lytic effects have been extensively studied, the defensins consist primarily of 0-sheet. Defensins fuse and lyse negatively charged liposomes but display reduced activity with neutral liposomes. These and other experiments suggest that fusion and lysis is mediated primarily by electrostatic forces and to a lesser extent, by hydrophobic interactions.Circular dichroism and fluorescence spectroscopy of native defensins indicate that the amphiphilic 0-sheet structure is maintained throughout the fusion process. Taken together, these results support the idea that proteinmediated membrane fusion depends not only on hydrophobic and electrostatic forces but also on the spatial arrangement of the amino acid residues to form a three-dimensional amphiphilic structure, which promotes the efficient mixing of the lipids between membranes. A molecular model for membrane fusion by defensins is presented, which takes into account the contributions of electrostatic forces, hydrophobic interactions, and structural amphiphilicity.

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Section: ~~ ~ ~~~~mentioning

confidence: 99%

Defensins promote fusion and lysis of negatively charged membranes

Fujii

Selsted

Eisenberg³

1993

Protein Science

155

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“…Cell purity (90-95% neutrophils) was assessed by Wright-Giemsa staining. Leucocytes were homogenized, centrifuged and chromatographed using the method reported previously [38]. The mixture of HNP1, HNP2 and HNP3 obtained after initial chromatographic separation was subjected to reverse-phase HPLC on a Rainin Dynamax-60A semi-preparative C18 column (10 mm х 250 mm) coupled to a guard column (10 mm х 50 mm) employing acetonitrile/water (each containing 0.1% TFA) linear gradient elution (flow rate 2.0 ml·min −1 ).…”

Section: Purification Of Native Human Neutrophil Defensinsmentioning

confidence: 99%

Large-scale synthesis and functional elements for the antimicrobial activity of defensins

Raj

Antonyraj

Karunakaran

2000

Biochemical Journal

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Human neutrophil defensins, and their analogues incorporating anionic, hydrophobic or cationic residues at the N- and C-termini, were synthesized by solid-phase procedures. The synthetic defensins were examined for their microbicidal activity against Candida albicans, two Gram-negative bacteria (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) and two Gram-positive bacteria (Streptococcus gordonii and Streptococcus mutans). The human neutrophil peptide 1 (HNP1) and HNP2 were found to be potent candidacidal agents. HNP3, which differs by one amino acid at the N-terminus of its sequence, was totally inactive. The Gram-negative bacteria A. actinomycetemcomitans and P. gingivalis and the Gram-positive bacteria S. gordonii and S. mutans were insensitive to human defensins. However, the insertion of two basic residues, such as arginine, at both the N-terminus and the C-terminus of HNP2 significantly enhanced antifungal and antibacterial activity. The addition of anionic residues, such as aspartic acid, at the N- and C-termini rendered the molecule totally inactive. The presence of two hydrophobic amino acids, such as valine, at the N-terminus of HNP2 and of two basic arginine residues at its C-terminus resulted in molecules that were optimally active against these oral pathogens. The results suggest that the N- and C-terminal residues in defensin peptides are the crucial functional elements that determine their microbicidal potency. The three-dimensional structure of all defensins constitutes the same amphiphilic β-sheet structure, with the polar face formed by the N- and C-terminal residues playing an important role in defining microbicidal potency and the antimicrobial spectrum. The enhanced microbicidal activity observed for defensin peptides with two basic residues at both the N- and C-termini could be due to optimization of the amphiphilicity of the structure, which could facilitate specific interactions with the microbial membranes.

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“…Although we are continually seeking more sensitive and specific tests to diagnose PJI prior to surgical intervention, there remains no diagnostic ''gold standard. '' In 1985, Ganz and colleagues isolated three small cysteine-rich peptides (CRPs) from human neutrophilic granules that demonstrated strong antimicrobial properties, and coined the term ''defensins'' [8]. It is now recognized that in response to bacterial pathogen-associated molecular patterns, neutrophils, macrophages, Tlymphocytes, and some epithelial cells can release a family of cationic molecules, the alpha defensins, which disrupt bacterial cell membranes [4].…”

Section: P Eriprosthetic Joint Infectionmentioning

confidence: 99%