Model of an F₁-likeX₀ ATPase encoded by the seven-gene clusters of Types 2 and 3 specific to mycoplasmas.

<p><b>A</b>. The F₁-like complex model of <i>Mmm</i> was drawn by similarity with the crystal structure of the <i>E. coli</i> F₁-ATPase (Pdb id: 3oaa) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038793#pone.0038793-Cingolani1" target="_blank">[27]</a> with the help of the Pymol software (<a href="http://www.pymol.org" target="_blank">http://www.pymol.org</a>) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038793#pone.0038793-DeLano1" target="_blank">[28]</a>. The X₀ complex proteins of <i>Mmm</i> were schematized on the basis of 2D structure predictions. Proteins 1 and 5 are depicted associated with the membrane, in accordance with the predicted transmembrane segments. Based on <i>in silico</i> and experimental results, the F₁-like complex, Protein 2 and the main part of Protein 5 were predicted to be cytoplasmic. Within this model, the F₁-like and the X₀ sectors are represented, but the way they could interact remains largely unclear. <b>B</b>. The genes of the clusters were arbitrarily numbered from 1 to 7. Gene names are indicated above the boxes representing the genes. TM, transmembrane segments. The proteins encoded by genes 3, 4, 6 and 7 were found to be related to the subunits γ, ε, α and β of the F₁F₀ ATPase, respectively.