Experimental topology information obtained on SSO0551 and theoretical 3D model M8 shown to be compatible. A – Schematic representation of experimental low-resolution structural information. SSO0551 sequence is displayed with its predicted secondary structural elements (α-helices and β-strands are represented by helices and arrows, respectively). The two conserved COG2042 motifs described in this study (I and II) and the 35 amino acids RLI motif are specified. Vertical arrows indicate sites of limited proteolysis that have been experimentally determined. Lysines labeled with NHS-biotin are indicated with asterisks and lysines involved in DTSSP cross-links are schematically bridged. Sequence numbering refers to the native version (untagged) of SSO0551 experimentally characterized. B – Schematic drawing of ab initio model M8. Secondary structure elements are shown as coil for α-helices, arrows for β-strands, and lines for loops. The color code follows a rainbow style where N terminus is in blue and C terminus in red. C – Molecular surface of ab initio model M8. The localization of solvent-exposed lysines, as determined by NHS-biotin labeling experiments, is colored in red whereas other lysines are colored in blue. This view shows the protein in the same orientation as in B.