Extended Data Fig. 1: Structure determination and analysis.

a, SDS–PAGE of recombinantly expressed and purified Mgm1. M, marker proteins; NI, whole-cell lysate, non-induced; I, whole-cell lysate, induced; R, whole-cell lysate, resuspended, collected cells; D, whole-cell lysate, disrupted cells; CL, cleared lysate; FT, flow-through; W, buffer wash; PC, after cleavage by PreScission Protease; L, as loaded onto gel filtration column (n = 5 independent experiments). b, Selenium sites and experimental density at 1.4σ before model building and refinement of the G domain (top left), stalk (top right), BSE (bottom left) and paddle domain (bottom right). c, Ribbon diagram of Mgm1 dimer, indicating the positions of confirmed methionines in ball-and-stick representation. Anomalous difference density is contoured at 2.5σ in magenta. An anomalous difference map was calculated from refined phases, resulting in discrete difference peaks indicating the positions of selenium atoms. Four selenium sites in the G domain, three in the BSE, two in the paddle domain and three in the stalk were used to determine the structure and verify the sequence assignment in the model. d, Mutations resulting in impaired lipid binding⁶⁰ or in temperature-sensitive inner mitochondrial membrane fusion deficits¹⁰ were mapped onto the crystal structure. Mutations localize to the G interface, the G domain/BSE interface, stalk interface-1 or the paddle domain. e, Sequence conservation of nine Mgm1 sequences (see Supplementary Fig. 1 for alignments) was plotted on the surface of an Mgm1 monomer. Magenta, high conservation; cyan, low conservation. Residues investigated in this study are labelled and interfaces and contact sites are circled.