Extended Data Fig. 1: Purification of native Pks13 from mycobacteria.
From: Structure and dynamics of the essential endogenous mycobacterial polyketide synthase Pks13
(a) Final Superose 6 size exclusion chromatography profile of Pks13. Two peaks containing Pks13 are labeled 1 and 2, in addition to the void peak and peak containing TEV protease. Pks13 peaks were run on non-reducing SDS-PAGE (Biorad #4561096) (b) and blue native PAGE (Invitrogen #BN1004BOX) (c), which were repeated twice with similar results. In SDS-PAGE (b) the protein runs at ~198 kDa, as expected for a protomer of Pks13. Blue native PAGE (c) indicates that majority of the protein is in a dimeric form, and higher oligomeric forms are present. Upon screening both peaks 1 and 2 on gold Quantifoil grids by cryoEM, peak 1 was selected for data collection since it produced more monodisperse particles that correspond to Pks13 dimers. We conclude that the Pks13 dimers associate loosely in solution, and that these readily dissociate to form monodisperse Pks13 dimers under the conditions in which the images were acquired. (d) 78.1% sequence coverage (highlighted red) by tryptic digested Pks13 fragments run on LC-MS-MS.
