The structure of MJ0391. (a) Ribbon diagram (stereo view) of the tertiary structure of MJ0391 (colored in a rainbow ramp from blue at the N-terminus to red at the C-terminus). (b) The ribbon diagram of the MJ0391 dimer in the asymmetric unit (shown in an arbitrary orientation). Subunit A is colored in a rainbow ramp as in (a), and subunit B is colored green. In the dimer, β6 of subunit A and β6’ of subunit B form an intermolecular antiparallel β-sheet. The MES molecule is shown as a stick model. All figures were produced with the PyMOL program (Schrödinger, LLC.), unless otherwise mentioned. (c) The quaternary structure of MJ0391. Stereo view of the intact tetramer arrangement of MJ0391, produced by the crystallographic 2-fold axis. The tetramer is shown in an arbitrary orientation. Subunits A-D are colored red, green, orange and blue, respectively. A few structural elements at the tetramer interface are labeled, for clarity.