D-Loop Mutation G42A/G46A Decreases Actin Dynamics

Abstract

Depolymerization and polymerization of the actin filament are indispensable in eukaryotes. The DNase I binding loop (D-loop), which forms part of the interface between the subunits in the actin filament, is an intrinsically disordered loop with a large degree of conformational freedom. Introduction of the double mutation G42A/G46A to the D-loop of the beta cytoskeletal mammalian actin restricted D-loop conformational freedom, whereas changes to the critical concentration were not large, and no major structural changes were observed. Polymerization and depolymerization rates at both ends of the filament were reduced, and cofilin binding was inhibited by the double mutation. These results indicate that the two glycines at the tip of the D-loop are important for actin dynamics, most likely by contributing to the large degree of conformational freedom.

Structural basis of rapid actin dynamics in the evolutionarily divergent Leishmania parasite

“…These data suggest the D-loop sequence composition may have an important role in determining cofilin binding. This is in line with a study showing that D-loop point-mutations altered cofilin binding 51 . Interestingly, also LmCofilin did not fragment RbActin filaments (Supplementary Fig.…”

Actin Isoform Composition and Binding Factors Fine-Tune Regulatory Impact of Mical Enzymes

“…Mical-induced oxidation was previously shown to affect First, we determined the Cc values of unoxidized actin forms and compared them to the published Cc values (Figure 3B-F, closed symbols). Unoxidized cytoplasmic and skeletal muscle α-actin had Cc values close to those previously reported [16,[26][27][28][29][30][31]. Our cardiac actin preparations appeared to have an improved polymerization propensity (compared to previously reported Cc data), which likely stems from differences in the experimental conditions [32,33].…”

ATP-dependent polymerization dynamics of bacterial actin proteins involved in Spiroplasma swimming

“…By contrast, the critical concentration of SpeMreB3 was estimated to be 18 times higher than that of SpeMreB5 ( figure 4 c ; electronic supplementary material, figure S9C, table 1 ). In actin sedimentation assays, the actin concentration in the supernatant fraction is consistent with the critical concentration [ 45 ]. However, for SpeMreB3 and SpeMreB5, the concentrations in the supernatant fractions were not constant and the linear-fit slope of the pellet amounts was not 1 ( figure 4 c ).…”