ScMreB5 filaments form double-protofilament assemblies independent of nucleotide hydrolysis. (A–D) Cryo-electron micrographs showing filaments of ScMreB5^WT in the presence of 5 mM ATP and MgCl₂ (A); ScMreB5^WT in the presence of 5 mM AMP-PNP and MgCl₂ (B); ScMreB5^WT in the presence of 5 mM ADP and MgCl₂ (C); and ScMreB5^E134A mutant (hydrolysis deficient) in the presence of 5 mM AMP-PNP and MgCl₂ (D). A few double protofilaments are highlighted by pairs of parallel white lines to enable easy visualization of the filament distribution. Concentration of protein used was 50 µM. Scale bar denotes 50 nm.