The Effects of Metal Ions and Nucleotides on the Conformation of Actin

Actin is a highly conserved cytoskeletal protein that is present in all eukaryotes. Polymerization of actin to filamentous actin is essential for numerous cellular processes. Abnormal actin dynamics are directly associated with a variety of diseases, including cancer, immunological and neurological disorders. However, the dynamics of actin are not fully understood. In this work, we study the effects of nucleotides and metal ions on conformation of F/G-actin using molecular dynamics (MD) simulations. Our results show that different nucleotides and metal ions change the conformation of actin. The state of Adenosine Triphosphate (ATP) binding on F-actin conformation is more stable than G-actin. The D-loop has a large fluctuation when Ca2+ binds to G-ATP-actin than Mg2+ binds. Adenosine Diphosphate (ADP) binding leads to a stronger residual correlation on F-actin conformation, while it is opposite on G-actin. In addition, the detailed interactions between nucleotides and adjacent residues are discussed on different states of actin. This work provides a structural basis for understanding how the different nucleotides/metal ions binding influences the conformation of actin.