Structural and functional characterization of the conserved salt bridge in mammalian paneth cell alpha-defensins: solution structures of mouse CRYPTDIN-4 and (E15D)-CRYPTDIN-4

TY - JOUR

T1 - Structural and functional characterization of the conserved salt bridge in mammalian paneth cell alpha-defensins

T2 - solution structures of mouse CRYPTDIN-4 and (E15D)-CRYPTDIN-4

AU - Rosengren, K Johan

AU - Daly, Norelle L

AU - Fornander, Liselotte M

AU - Jönsson, Linda M H

AU - Shirafuji, Yoshinori

AU - Qu, Xiaoqing

AU - Vogel, Hans J

AU - Ouellette, Andre J

AU - Craik, David J

AU - Kedström, Linda Maria Haugaard

PY - 2006/9/22

Y1 - 2006/9/22

N2 - alpha-Defensins are mediators of mammalian innate immunity, and knowledge of their structure-function relationships is essential for understanding their mechanisms of action. We report here the NMR solution structures of the mouse Paneth cell alpha-defensin cryptdin-4 (Crp4) and a mutant (E15D)-Crp4 peptide, in which a conserved Glu(15) residue was replaced by Asp. Structural analysis of the two peptides confirms the involvement of this Glu in a conserved salt bridge that is removed in the mutant because of the shortened side chain. Despite disruption of this structural feature, the peptide variant retains a well defined native fold because of a rearrangement of side chains, which result in compensating favorable interactions. Furthermore, salt bridge-deficient Crp4 mutants were tested for bactericidal effects and resistance to proteolytic degradation, and all of the variants had similar bactericidal activities and stability to proteolysis. These findings support the conclusion that the function of the conserved salt bridge in Crp4 is not linked to bactericidal activity or proteolytic stability of the mature peptide.

AB - alpha-Defensins are mediators of mammalian innate immunity, and knowledge of their structure-function relationships is essential for understanding their mechanisms of action. We report here the NMR solution structures of the mouse Paneth cell alpha-defensin cryptdin-4 (Crp4) and a mutant (E15D)-Crp4 peptide, in which a conserved Glu(15) residue was replaced by Asp. Structural analysis of the two peptides confirms the involvement of this Glu in a conserved salt bridge that is removed in the mutant because of the shortened side chain. Despite disruption of this structural feature, the peptide variant retains a well defined native fold because of a rearrangement of side chains, which result in compensating favorable interactions. Furthermore, salt bridge-deficient Crp4 mutants were tested for bactericidal effects and resistance to proteolytic degradation, and all of the variants had similar bactericidal activities and stability to proteolysis. These findings support the conclusion that the function of the conserved salt bridge in Crp4 is not linked to bactericidal activity or proteolytic stability of the mature peptide.

KW - Amino Acid Sequence

KW - Animals

KW - Anti-Infective Agents

KW - Humans

KW - Hydrogen-Ion Concentration

KW - Magnetic Resonance Spectroscopy

KW - Matrix Metalloproteinase 7

KW - Mice

KW - Molecular Sequence Data

KW - Mutation

KW - Rabbits

KW - Solutions

KW - Structure-Activity Relationship

KW - Temperature

KW - alpha-Defensins

U2 - 10.1074/jbc.M604992200

DO - 10.1074/jbc.M604992200

M3 - Journal article

C2 - 16857681

SN - 0021-9258

VL - 281

SP - 28068

EP - 28078

JO - The Journal of Biological Chemistry

JF - The Journal of Biological Chemistry

IS - 38

ER -