2LEY

Solution structure of (R7G)-Crp4

Summary for 2LEY

• Entry DOI: 10.2210/pdb2ley/pdb
• Related: 2GW9 2GWP 2LEW
• NMR Information: BMRB: 17733
• Descriptor: Alpha-defensin 4 (1 entity in total)
• Functional Keywords: antimicrobial protein
• Biological source: Mus musculus (mouse)
• Cellular location: Secreted: P28311
• Total number of polymer chains: 1
• Total formula weight: 3671.47

Authors

Rosengren, K.,Andersson, H.S.,Haugaard-Kedstrom, L.M.,Bengtsson, E.,Daly, N.L.,Figueredo, S.M.,Qu, X.,Craik, D.J.,Ouellette, A.J. (deposition date: 2011-06-26, release date: 2012-05-16, Last modification date: 2024-11-06)

Primary citation

Andersson, H.S.,Figueredo, S.M.,Haugaard-Kedstrom, L.M.,Bengtsson, E.,Daly, N.L.,Qu, X.,Craik, D.J.,Ouellette, A.J.,Rosengren, K.J.
The alpha-defensin salt-bridge induces backbone stability to facilitate folding and confer proteolytic resistance.
Amino Acids, 43:1471-1483, 2012

PubMed Abstract: Salt-bridge interactions between acidic and basic amino acids contribute to the structural stability of proteins and to protein-protein interactions. A conserved salt-bridge is a canonical feature of the α-defensin antimicrobial peptide family, but the role of this common structural element has not been fully elucidated. We have investigated mouse Paneth cell α-defensincryptdin-4 (Crp4) and peptide variants with mutations at Arg7 or Glu15 residue positions to disrupt the salt-bridge and assess the consequences on Crp4 structure, function, and stability. NMR analyses showed that both (R7G)-Crp4 and (E15G)-Crp4 adopt native-like structures, evidence of fold plasticity that allows peptides to reshuffle side chains and stabilize the structure in the absence of the salt-bridge. In contrast, introduction of a large hydrophobic side chain at position 15, as in (E15L)-Crp4 cannot be accommodated in the context of the Crp4 primary structure. Regardless of which side of the salt-bridge was mutated, salt-bridge variants retained bactericidal peptide activity with differential microbicidal effects against certain bacterial cell targets, confirming that the salt-bridge does not determine bactericidal activity per se. The increased structural flexibility induced by salt-bridge disruption enhanced peptide sensitivity to proteolysis. Although sensitivity to proteolysis by MMP7 was unaffected by most Arg(7) and Glu(150 substitutions, every salt-bridge variant was degraded extensively by trypsin. Moreover, the salt-bridge facilitates adoption of the characteristic α-defensin fold as shown by the impaired in vitro refolding of (E15D)-proCrp4, the most conservative salt-bridge disrupting replacement. In Crp4, therefore, the canonical α-defensin salt-bridge facilitates adoption of the characteristic α-defensin fold, which decreases structural flexibility and confers resistance todegradation by proteinases.

PubMed: 22286872
DOI: 10.1007/s00726-012-1220-3

Experimental method

SOLUTION NMR