An Allosteric Circuit in Caspase-1 Export

@article{citeulike:4281480, abstract = {Structural studies of caspase-1 reveal that the dimeric thiol protease can exist in two states: in an on-state, when the active site is occupied, or in an off-state, when the active site is empty or when the enzyme is bound by a synthetic allosteric ligand at the dimer interface  15 \r{A} from the active site. A network of 21 hydrogen bonds from nine side chains connecting the active and allosteric sites change partners when going between the on-state and the off-state. Alanine-scanning mutagenesis of these nine side chains shows that only two of them—Arg286 and Glu390, which form a salt bridge—have major effects, causing 100- to 200-fold reductions in catalytic efficiency ( k cat / K m ). Two neighbors, Ser332 and Ser339, have minor effects, causing 4- to 7-fold reductions. A more detailed mutational analysis reveals that the enzyme is especially sensitive to substitutions of the salt bridge: even a homologous R286K substitution causes a 150-fold reduction in k cat / K m . X-ray crystal structures of these variants suggest the importance of both the salt bridge interaction and the coordination of solvent water molecules near the allosteric binding pocket. Thus, only a small subset of side chains from the larger hydrogen bonding network is critical for activity. These form a contiguous set of interactions that run from one active site through the allosteric site at the dimer interface and onto the second active site. This subset constitutes a functional allosteric circuit or ” hot wire” that promotes site-to-site coupling.}, author = {Datta, Debajyoti and Scheer, Justin M. and Romanowski, Michael J. and Wells, James A.}, citeulike-article-id = {4281480}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.jmb.2008.06.040}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/S0022283608007420}, day = {19}, doi = {10.1016/j.jmb.2008.06.040}, issn = {00222836}, journal = {Journal of Molecular Biology}, keywords = {allostery, dimerization, experiment, mutation, protein, structural\_change}, month = {September}, number = {5}, pages = {1157--1167}, posted-at = {2009-04-07 08:39:24}, priority = {2}, title = {An Allosteric Circuit in Caspase-1}, url = {http://dx.doi.org/10.1016/j.jmb.2008.06.040}, volume = {381}, year = {2008} }

TY - JOUR ID - citeulike:4281480 L3 - citeulike-article-id:4281480 N2 - Structural studies of caspase-1 reveal that the dimeric thiol protease can exist in two states: in an on-state, when the active site is occupied, or in an off-state, when the active site is empty or when the enzyme is bound by a synthetic allosteric ligand at the dimer interface  15 Å from the active site. A network of 21 hydrogen bonds from nine side chains connecting the active and allosteric sites change partners when going between the on-state and the off-state. Alanine-scanning mutagenesis of these nine side chains shows that only two of them—Arg286 and Glu390, which form a salt bridge—have major effects, causing 100- to 200-fold reductions in catalytic efficiency ( k cat / K m ). Two neighbors, Ser332 and Ser339, have minor effects, causing 4- to 7-fold reductions. A more detailed mutational analysis reveals that the enzyme is especially sensitive to substitutions of the salt bridge: even a homologous R286K substitution causes a 150-fold reduction in k cat / K m . X-ray crystal structures of these variants suggest the importance of both the salt bridge interaction and the coordination of solvent water molecules near the allosteric binding pocket. Thus, only a small subset of side chains from the larger hydrogen bonding network is critical for activity. These form a contiguous set of interactions that run from one active site through the allosteric site at the dimer interface and onto the second active site. This subset constitutes a functional allosteric circuit or “hot wire” that promotes site-to-site coupling. IS - 5 JF - Journal of Molecular Biology SN - 00222836 EP - 1167 TI - An Allosteric Circuit in Caspase-1 VL - 381 SP - 1157 KW - allostery KW - dimerization KW - experiment KW - mutation KW - protein KW - structural_change AU - Datta, Debajyoti AU - Scheer, Justin AU - Romanowski, Michael AU - Wells, James PY - 2008/09/19/ UR - http://dx.doi.org/10.1016/j.jmb.2008.06.040 ER -