Fig. 2: Systematic cryo-EM approach.
From: Dissecting the conformational complexity and mechanism of a bacterial heme transporter
a, Volume map representation of the \({{{\mathrm{IF}}}}_{{{{\mathrm{as}}}}\;{{{\mathrm{isolated}}}}}^{{{{\mathrm{heme}}}}}\) structure representing the general architecture of CydDC. Dark green, CydC; light green, CydD. The left shows a cross-section of the membrane domain composed of 12 TMs displaying arrangement and geometry typical for type IV ABC transporters. The right shows a cross-section of NBDs. The subdomains ABCα and ABCβ of each NBD are highlighted. b, Schematic organization of CydC and CydD subunits. TMs are indicated by numbers. Residues important for ATP hydrolysis and signal transduction between TMH and NB domains are highlighted. c, Summary of systematic single-particle cryo-EM studies. The left shows volume maps and corresponding ribbon models. Each circle represents a distinct conformation of CydDC. Numbers around circles refer to sample condition of CydDC analyzed by electron microscopy. Bold numbers indicate that the given conformation was present under that condition. The right shows a summarized information panel about the analyzed CydDC variants, presence and absence of heme, nucleotide and additional putative substrate molecules. CydDCwt, beige; CydDCH85A, light blue; CydDCE500Q, purple. IF, inward-facing; Occ, occluded; GSSG, glutathione disulfide; CSSC, cystine.
