Beta-defensins bind microbial membranes causing disruption

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Reaction [uncertain]
Homo sapiens
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Binding and disruption of microbial membranes is widely believed to be the primary mechanism of action for beta-defensins. There is no direct evidence of this, but a growing number of studies support this model (Pazgier et al. 2006). Beta-defensins have antimicrobial properties that correlate with membrane permeabilization effects (Antcheva et al. 2004, Sahl et al. 2005, Yenugu et al. 2004). The sensitivity of microbes to beta-defensins correlates with the lipid composition of the membrane; more negatively-charged lipids correlate with larger beta-defensin 103-induced changes in membrane capacitance (Bohling et al. 2006). Beta-defensin-103 was observed to give rise to ionic currents in Xenopus membranes (Garcia et al. 2001) and cell wall perforation was observed in S. aureus when treated with HBD-3 (Harder et al. 2001). Two models explain how membrane disruption takes place. The 'pore model' postulates that beta-defenisns form transmembrane pores in a similar manner to alpha-defensins, while the 'carpet model' suggests that beta-defensins act as detergents, causing a less organised disruption. Beta-defensins have a structure that is topologically distinct from that of alpha-defensins, suggesting a different mode of dimerization and an electrostatic charge-based mechanism of membrane permeabilization rather than a mechanism based on formation of bilayer-spanning pores (Hoover et al. 2000).
Literature References
PubMed ID Title Journal Year
11702237 Identification of a novel, multifunctional beta-defensin (human beta-defensin 3) with specific antimicrobial activity. Its interaction with plasma membranes of Xenopus oocytes and the induction of macrophage chemoattraction

Jaumann, F, Adermann, K, Vogelmeier, C, Bals, R, Schulz, S, Klüver, E, Hedrich, R, García, JR, Rodríguez-Jiménez, J, Krause, A, Forssmann, WG, Becker, D, Forssmann, U

Cell Tissue Res 2001
11085990 Isolation and characterization of human beta -defensin-3, a novel human inducible peptide antibiotic

Bartels, J, Christophers, E, Harder, J, Schroder, JM

J Biol Chem 2001
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