ScMreB5 possesses a conserved protofilament arrangement and nucleotide-binding pocket. (A and B) Crystal structures of ScMreB5 in ADP (PDB accession no. 7BVZ) and AMP-PNP (PDB accession no. 7BVY) bound states. The subdomains IA, IB, IIA, and IIB are colored and labeled. RMSD values of each subdomain upon superposition with the corresponding subdomains in CcMreB along with the number of Cα atoms superposed are given below the subdomain labels. N- and C-terminal ends are labeled N and C, respectively, and the terminal residue numbers are marked. The chain breaks in 7BVZ are also labeled by their residue numbers (93 and 97). (C and D) Electron density for the bound ADP and AMP-PNP with Mg²⁺ and K⁺ (composite omit map F_o − F_c shown at 2.0 σ). (E) Protofilament structures of CcMreB (PDB accession no. 4CZF), ScMreB5 with bound ADP (PDB accession no. 7BVZ) and AMP-PNP (labeled as ANP in figure; PDB accession no. 7BVY). Both of the nucleotide-bound structures of ScMreB5 have the same subunit repeat as CcMreB (51.1 Å) in their protofilament assemblies. Individual chains are colored according to the subdomains. (F) Zoomed-in view of the residues at the nucleotide binding pocket. Residues of ScMreB5–AMP-PNP (PDB accession no. 7BVY; domain-wise colors) are shown superimposed with corresponding residues in ScMreB5–ADP (PDB accession no. 7BVZ; blue-gray). (G) Residues involved in Mg²⁺ coordination in ScMreB5 (Asp156, Glu134, and Asp12). Distances for Mg²⁺ coordination are marked by dotted lines for ScMreB5–AMP-PNP. (H) Residues adjacent to the γ-phosphate, Glu134 and Thr161, at the nucleotide-binding pocket. Distances with the catalytic water are marked by dotted lines for CcMreB structure.