1. Alpha-defensin 1 (human neutrophil protein 1) as an antichemotactic agent for human polymorphonuclear leukocytes
P S Grutkoski, C T Graeber, Y P Lim, A Ayala, H H Simms Antimicrob Agents Chemother. 2003 Aug;47(8):2666-8. doi: 10.1128/AAC.47.8.2666-2668.2003.
Medium conditioned by tumor necrosis factor alpha (TNF-alpha)-stimulated polymorphonuclear leukocytes (PMN) (CM-TNF) suppresses PMN migration. Therefore, we wished to identify the agent(s) in CM-TNF that mediated antichemotactic activity. CM-TNF was fractionated by high-performance liquid chromatography, and one fraction with antichemotactic activity contained the bactericidal protein human neutrophil protein 1 (HNP-1). We showed that HNP-1 suppresses PMN migration to formyl-methionyl-leucyl-phenylalanine but not to interleukin 8.
2. Molecular determinants for the interaction of human neutrophil alpha defensin 1 with its propeptide
Guozhang Zou, Erik de Leeuw, Jacek Lubkowski, Wuyuan Lu J Mol Biol. 2008 Sep 19;381(5):1281-91. doi: 10.1016/j.jmb.2008.06.066. Epub 2008 Jun 28.
Human neutrophil alpha-defensins (HNPs) are cationic antimicrobial peptides that are synthesized in vivo as inactive precursors (proHNPs). Activation requires proteolytic excision of their anionic N-terminal inhibitory pro peptide. The pro peptide of proHNP1 also interacts specifically with and inhibits the antimicrobial activity of HNP1 inter-molecularly. In the light of the opposite net charges segregated in proHNP1, functional inhibition of the C-terminal defensin domain by its propeptide is generally thought to be of electrostatic nature. Using a battery of analogs of the propeptide and of proHNP1, we identified residues in the propeptide region important for HNP1 binding and inhibition. Only three anionic residues in the propeptide, Glu(15), Asp(20) and Glu(23), were modestly important for interactions with HNP1. By contrast, the hydrophobic residues in the central part of the propeptide, and the conserved hydrophobic motif Val(24)Val(25)Val(26)Leu(28) in particular, were critical for HNP1 binding and inhibition. Neutralization of all negative charges in the propeptide only partially activated the bactericidal activity of proHNP1. Our data indicate that hydrophobic forces have a dominant role in mediating the interactions between HNP1 and its propeptide--a finding largely contrasting the commonly held view that the interactions are of an electrostatic nature.
3. Human neutrophil alpha-defensin 4 inhibits HIV-1 infection in vitro
Zhibin Wu, Fiorenza Cocchi, David Gentles, Bryan Ericksen, Jacek Lubkowski, Anthony Devico, Robert I Lehrer, Wuyuan Lu FEBS Lett. 2005 Jan 3;579(1):162-6. doi: 10.1016/j.febslet.2004.11.062.
Human neutrophil alpha-defensin 4 (HNP4) is more effective than HNP1-3 in protecting human peripheral blood mononuclear cells from infection by both X4 and R5 HIV-1 strains. HNP4 binds to both CD4 and gp120 approximately two orders of magnitude weaker than does HNP1, and is less effectively sequestered by glycosylated serum proteins than HNP1. These results suggest that the HIV-1 inhibition by HNP4 stems at least partially from a unique and lectin-independent property of HNP4 with CD4 and/or gp120. Our finding identifies an anti-HIV-1 property of HNP4 and may have implications in the development of new antiviral agents for AIDS therapy.
