Rotors subunit interaction with

Shown in cross-eye stereo side view in Figure 8.28 are three views of the Fo-rotor, that is, of the rotating wheel of the Fo-motor. At this level of resolution each residue is given as a sphere. Furthermore, each of the 10 subunits of the Fo-rotor is represented as a double-stranded a-helical hairpin with the ends at the top (cytosolic side) and the turn at the bottom (matrix side) and with one side of the hairpin in direct interaction with the lipid bilayer and the other side forming the inner wall of the rotating wheel. In Figure 8.28A the aspartic acid residue D61 is noted from outside. This residue exists with its side chain as a carboxyl (-COOH) when adjacent to the lipid bilayer, but it releases its proton to form the carboxylate (-COO ) when it reaches the effective channel when adjacent to the a-subunit. 

This configuration, which for simplicity may be designated as EGC, makes a profound statement. As shown in Figure 8.34A, the association between the P-empty subunit and the y-rotor is profoundly hydrophobic at the levels of both the nucleotide sites and the interaction as the y-rotor enters the (aP)s construct. The most hydrophobic face of the y-rotor hydrophobi-cally associates extensively with the P-empty subunit. Interestingly, except at the very tip of the y-rotor, there is no interaction with the a-ATP(C) subimit instead, there is an aqueous chasm separating G from C down to but not including the tip of the y-rotor. It is difficult to... 

In the DGB interaction shown in Figure 8.34B, the interaction of the y-rotor with the P-ADP subunit is significantly hydrophobic, but in a limited way when compared with the interaction, EG, between P-empty subunit and the y-rotor. For this DGB configuration, the a-ATP(B) interaction with the y-rotor is partly re-established. 

The rotor that is driven by the Fo-motor comprises a single y-subunit and a small e-subunit attached to the y-subunit at a point proximal to the base of the Fo-motor. This is called the y-rotor. In the hydrophobic elastic consilient mechanism, the interactions of a hydrophobi-cally asymmetric y-rotor with the housing of the Fi-motor with different occupancy states of the catalytic sites constitute the basis for mechano-chemical transduction of the Fi-motor. 

A Side Views (3) of the Interaction of the Paired Diametrically Opposed Subunits with the Asymmetric Rotor... 

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