Fig. 1: Overall architecture of the M. mazei Mtr complex.

A Segmented cryo-EM composite map of the Mtr complex shown from different orientations. B Corresponding (atomic) model of the Mtr complex. In the side views of both map and model, membrane, cytosolic and extracellular compartments are labelled, and the position of the membrane is indicated by dashed lines. C Mtr-catalysed reaction with substrates and products shown as structural formulas. D Surface representation of the Mtr complex (with cytosolic MtrA and MtrI omitted). Curved arrows indicate substrate-to-product conversion, positioned at the site of catalysis within the surface model.