title: Molecular Recognition of Muramyl Dipeptide Occurs in the Leucine-rich Repeat Domain of Nod2.
abstract: Genetic mutations in the innate immune receptor nucleotide-binding oligomerization domain-containing 2 (Nod2) have demonstrated increased susceptibility to Crohn's disease, an inflammatory bowel disease that is hypothesized to be accompanied by changes in the gut microbiota. Nod2 responds to the presence of bacteria, specifically a fragment of the bacterial cell wall, muramyl dipeptide (MDP). The proposed site of this interaction is the leucine-rich repeat (LRR) domain. Surface plasmon resonance and molecular modeling were used to investigate the interaction of the LRR domain with MDP. A functional and pure LRR domain was obtained from Escherichia coli expression in high yield. The LRR domain binds to MDP with high affinity, with a KDof 212 ± 24 nM. Critical portions of the receptor were determined by mutagenesis of putative binding residues. Fragment analysis of MDP revealed that both the peptide and carbohydrate portion contribute to the binding interaction.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Mackenzie L
authors.initials: ML
authors.lastname: Lauro
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: D'Ambrosio
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Bahnson
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Catherine Leimkuhler
authors.initials: CL
authors.lastname: Grimes
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000378:metabolism*; D000276:Adjuvants, Immunologic / Q000378:metabolism*; D001665:Binding Sites; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008958:Models, Molecular; D053473:Nod2 Signaling Adaptor Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D020349:Surface Plasmon Resonance
chemical_list: D000276:Adjuvants, Immunologic; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D007930:Leucine
keywords: innate immunity; leucine-rich repeat domain; muramyl dipeptide; nucleotide-binding oligomerization domain-containing 2; peptidoglycan; surface plasmon resonance