4LBF

Crystal structure of HUMAN ALPHA-DEFENSIN 1 (HNP1) I20A/L25A mutant

Summary for 4LBF

• Entry DOI: 10.2210/pdb4lbf/pdb
• Related: 3GNY 4LB1 4LB7 4LBB
• Descriptor: Neutrophil defensin 1, GLYCEROL (3 entities in total)
• Functional Keywords: antimicrobial peptide, human alpha defensin 1, human neutrophil peptide 1, antibiotic, antiviral defense, defensin, disulfide bond, fungicide, phosphoprotein, secreted, antimicrobial protein
• Biological source: Homo sapiens (human)
• Cellular location: Secreted: P59665
• Total number of polymer chains: 8
• Total formula weight: 27035.70

Authors

Tolbert, W.D.,Wu, X.,Pazgier, M. (deposition date: 2013-06-20, release date: 2013-11-27, Last modification date: 2023-09-20)

Primary citation

Zhao, L.,Tolbert, W.D.,Ericksen, B.,Zhan, C.,Wu, X.,Yuan, W.,Li, X.,Pazgier, M.,Lu, W.
Single, Double and Quadruple Alanine Substitutions at Oligomeric Interfaces Identify Hydrophobicity as the Key Determinant of Human Neutrophil Alpha Defensin HNP1 Function.
Plos One, 8:e78937-e78937, 2013

PubMed Abstract: HNP1 is a human alpha defensin that forms dimers and multimers governed by hydrophobic residues, including Tyr¹⁶, Ile²⁰, Leu²⁵, and Phe²⁸. Previously, alanine scanning mutagenesis identified each of these residues and other hydrophobic residues as important for function. Here we report further structural and functional studies of residues shown to interact with one another across oligomeric interfaces: I20A-HNP1 and L25A-HNP1, plus the double alanine mutants I20A/L25A-HNP1 and Y16A/F28A-HNP1, and the quadruple alanine mutant Y16A/I20A/L25A/F28A-HNP1. We tested binding to HIV-1 gp120 and HNP1 by surface plasmon resonance, binding to HIV-1 gp41 and HNP1 by fluorescence polarization, inhibition of anthrax lethal factor, and antibacterial activity using the virtual colony count assay. Similar to the previously described single mutant W26A-HNP1, the quadruple mutant displayed the least activity in all functional assays, followed by the double mutant Y16A/F28A-HNP1. The effects of the L25A and I20A single mutations were milder than the double mutant I20A/L25A-HNP1. Crystallographic studies confirmed the correct folding and disulfide pairing, and depicted an array of dimeric and tetrameric structures. These results indicate that side chain hydrophobicity is the critical factor that determines activity at these positions.

PubMed: 24236072
DOI: 10.1371/journal.pone.0078937

Experimental method

X-RAY DIFFRACTION (1.7 Å)