Allosteric effects on lactose repressor protein and DNA complex: MD and ab initio FMO calculations

Abstract

Lactose repressor protein (LacR) controls the transcriptional mechanism of gene information from DNA to mRNA in a ligand-dependent manner. Although the ligand-binding to LacR was found to change the mechanism drastically, the effect of ligand-binding on the conformation of LacR+DNA complex has not been clarified at atomic and electronic levels. We here investigated the change in conformation of LacR-dimer+DNA complex induced by the ligand-binding, using molecular dynamics simulations and ab initio fragment molecular orbital calculation. The results elucidate that the binding of an inducer to LacR significantly changes the LacR structure to cause strong interactions between LacR monomers, resulting in weakening the interactions between LacR-dimer and DNA.