4e82 | pdb_00004e82

Crystal structure of monomeric variant of human alpha-defensin 5, HD5 (Glu21EMe mutant)

spinqualitylabelsall models 4e82, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4e82 is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: EME Related: 1zmp, 4e83, 4e86 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Human alpha-defensins are cationic peptides that self-associate into dimers and higher-order oligomers. They bind protein toxins, such as anthrax lethal factor (LF), and kill bacteria, including Escherichia coli and Staphylococcus aureus, among other functions. There are six members of the human alpha-defensin family: four human neutrophil peptides, including HNP1, and two enteric human defensins, including HD5. We subjected HD5 to comprehensive alanine scanning mutagenesis. We then assayed LF binding by surface plasmon resonance, LF activity by enzyme kinetic inhibition, and antibacterial activity by the virtual colony count assay. Most mutations could be tolerated, resulting in activity comparable with that of wild type HD5. However, the L29A mutation decimated LF binding and bactericidal activity against Escherichia coli and Staphylococcus aureus. A series of unnatural aliphatic and aromatic substitutions at position 29, including aminobutyric acid (Abu) and norleucine (Nle) correlated hydrophobicity with HD5 function. The crystal structure of L29Abu-HD5 depicted decreased hydrophobic contacts at the dimer interface, whereas the Nle-29-HD5 crystal structure depicted a novel mode of dimerization with parallel beta strands. The effect of mutating Leu(29) is similar to that of a C-terminal hydrophobic residue of HNP1, Trp(26). In addition, in order to further clarify the role of dimerization in HD5 function, an obligate monomer was generated by N-methylation of the Glu(21) residue, decreasing LF binding and antibacterial activity against S. aureus. These results further characterize the dimer interface of the alpha-defensins, revealing a crucial role of hydrophobicity-mediated dimerization. Functional determinants of human enteric alpha-defensin HD5: crucial role for hydrophobicity at dimer interface.,Rajabi M, Ericksen B, Wu X, de Leeuw E, Zhao L, Pazgier M, Lu W J Biol Chem. 2012 Jun 22;287(26):21615-27. Epub 2012 May 9. PMID:22573326 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Defensin

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