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PDBsum entry 4lbb
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Antimicrobial protein
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PDB id
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4lbb
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PDB id:
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| Name: |
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Antimicrobial protein
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Title:
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Crystal structure of human alpha-defensin 1 (hnp1) i20a mutant
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Structure:
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Neutrophil defensin 1. Chain: a, b. Synonym: defensin, alpha 1, hnp-1, hp-1, hp1, hp 1-56, neutrophil defensin 2, hnp-2, hp-2, hp2. Engineered: yes. Mutation: yes
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Source:
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Synthetic: yes. Homo sapiens. Human. Organism_taxid: 9606
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Resolution:
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1.72Å
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R-factor:
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0.202
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R-free:
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0.229
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Authors:
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W.D.Tolbert,X.Wu,M.Pazgier
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Key ref:
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L.Zhao
et al.
(2013).
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.
PubMed id:
DOI:
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Date:
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20-Jun-13
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Release date:
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27-Nov-13
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PROCHECK
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Headers
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References
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P59665
(DEF1_HUMAN) -
Neutrophil defensin 1 from Homo sapiens
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Seq:
Struc:
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94 a.a.
30 a.a.*
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Key: |
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PfamA domain |
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Secondary structure |
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*
PDB and UniProt seqs differ
at 1 residue position (black
cross)
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DOI no:
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Plos One
8:e78937
(2013)
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PubMed id:
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Single, double and quadruple alanine substitutions at oligomeric interfaces identify hydrophobicity as the key determinant of human neutrophil alpha defensin HNP1 function.
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L.Zhao,
W.D.Tolbert,
B.Ericksen,
C.Zhan,
X.Wu,
W.Yuan,
X.Li,
M.Pazgier,
W.Lu.
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ABSTRACT
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HNP1 is a human alpha defensin that forms dimers and multimers governed by
hydrophobic residues, including Tyr(16), Ile(20), Leu(25), and Phe(28).
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.
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