Actin is a protein ubiquitously expressed in the cytoplasm of the cells. This protein undergoes important structural transformations to pass from a monomeric G-actin to a filamentous F-actin form. Furthermore, different isoforms exist such as α and β actins. While the α-actin isoform was thoroughly studied using molecular dynamics simulations, the dynamics of the β-actin isoform remains unexplored. Here, we have used the AMOEBA polarizable force field coupled with adaptive sampling to investigate the plasticity of the β-actin. This highlighted the role of a post translational modification, i.e. the histidine 73 methylation, to enhance the opening of the actin cleft and change allosteric paths linking the two distant subdomains SD2 and SD4. The action of the methylation can be also modulated by the type of nucleotide bound in the actin cavity and the type of ions surrounding the protein. Taken together, these results shed new lights onto the plasticity of the β-actin isoform and the coordinated role of several environmental factors. These results may help designing new types of molecules, such as allosteric modulators, specifically targeting the β-actin isoform.