Fig. 1.

Structure of TAO. Long helices are labeled α1 to α6 and short ones S1 to S4. Diiron and hydroxo atoms are shown as magenta spheres. (A) Dimeric structure of TAO viewed roughly perpendicular (Left) and parallel (Right) to the helix axes. Helices are shown as cylinders. Chain A is colored in rainbow from blue (N terminus) to red (C terminus) and chain B in pink. (B) Surface representation of the TAO dimer showing the hydrophobic (Left) and hydrophilic (Right) surfaces. Colors are according to the following hydrophobicity scale: red, high hydrophobicity; white, low hydrophobicity (www.pymolwiki.org/index.php/Color_h). (C) Proposed binding model of the TAO dimer to membranes shown by surface (Left) and cartoon (Right) representations. The hydrophobic region on the molecular surface of the TAO dimer faces the membrane. Conserved basic amino acid residues, which are distributed along a boundary between the hydrophobic and hydrophilic regions of the dimer surface, are colored in blue. Residue names are labeled in black (asterisk denotes in chain B).