Analysis of Nucleotide Binding Characteristics in NOD2 Proteins and Pathologies
The signal transducing ATPases with numerous domains (STAND) proteins are members of the extended ATPase associated with diverse cellular activities (AAA+) superfamily of P-loop NTPase proteins. These proteins act as molecular switches that cycle between ADP-bound and ATP-bound states, which determines their activation and inactivation. Members of the nucleotide-binding and leucine-rich repeat containing (NLR) protein family have a similar nucleotide-binding oligomerization domain (NOD) domain structure as these STAND ATPases. We examined this model in the context of the NLR family protein, nucleotide-binding and oligomerization domain containing 2 protein (NOD2), a protein that binds cytosolic muramyl dipeptide (MDP) and activates NF-κB, MAPK and autophagy signaling pathways. We mutated the NOD2 Walker A motif, which is known to bind nucleotides, to disrupt nucleotide binding in NOD2 and pathogenic alleles. These mutations caused a decrease in NOD2 binding to (CARD)-containing serine/threonine kinase (RIP2K), as well as a decrease in NF-κB activity in HEK293T cells. Interestingly, mutation of the NOD2 Walker A motif did not seem to abrogate NOD2-ATG16L binding or NOD2 homo-oligomerization, suggesting that while nucleotide-binding is necessary for NOD2-RIP2K hetero-oligomerization and NOD2-mediated NF-κB signaling, it is not necessary for NOD2-ATG16L binding and NOD2 homo-oligomerization. These data suggest that nucleotide binding is only required for interactions with some proteins, but not others. In light of these new data, we suggest an alternative model for NOD2 activation.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2015
- F&M Theses Collection