Fig. 5: Interaction sites within Eg-SC III2 + IV2.
From: Euglena’s atypical respiratory chain adapts to the discoidal cristae and flexible metabolism
Matrix (a) and side (b) views of Eg-SC III2 + IV2 interaction sites 1–3 with individual complexes shown as colored transparent surfaces. Rieske heads are shown as light blue solid surfaces. c Zoom-ins of Eg-CIII2 + CIV2 interaction site 1. Key residues forming polar contacts are shown as sticks and colored by elements. In site 1 MPP-α’ β hairpin (red) wedges into a cleft on CIV surface. d Alignment of SC III2 + IV1/2 from different species by the COB dimer viewed from the matrix side, including, M. musculus unlocked (PDB 7O3C), M. musculus locked (PDB 7O37), V. radiata (PDB 7JRP), S. cerevisiae (PDB 6T0B) and E. gracilis (this study). The matrix domain and the IMS helmet-like domain of Eg-CIV are shown as colored solid surfaces (e) and cartoons (f) in the context of the Eg-CIV. g Structural alignment of Eg-COX3 and Eg-COXEG1 to human COX3 (slate, PDB 5Z62) demonstrating that TMHs from the two Eg subunits together constitute a canonical seven-TMH COX3 subunit found in mammals.
