Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction.

摘要: Clamp loaders are AAA+ ATPases that load sliding clamps onto DNA. We mapped the mutational sensitivity of T4 bacteriophage clamp and loader by deep mutagenesis, found residues not involved in catalysis or binding display remarkable tolerance to mutation. An exception is a glutamine residue module (Gln 118) located at catalytic interfacial site. Gln 118 forms hydrogen-bonded junction helical unit we term central coupler, because it connects centers DNA clamp. A suppressor mutation indicates hydrogen bonding important, molecular dynamics simulations reveal maintains rigidity coupler. The glutamine-mediated preserved diverse ATPases, suggesting connected network bonds links ATP molecules an essential aspect allosteric communication these proteins.