complex. Furthermore, the asymmetric nature of the enzyme suggests that the two b

subunits cannot participate in the exact same interactions. For example, the b subunit

cannot have the same contacts with the single a in the membrane-spanning region and

likewise with the 6 subunit at the carboxyl-terminus. The unique experimental system

described in Chapters 2 and 3 will be used to investigate the individual roles and

positions of each b subunit. The experiments will heavily rely on the use of defective b

subunits along with very efficient and well characterized chemical crosslinking

techniques.

Length of the Peripheral Stalk in F1Fo ATP Synthase Complexes Incorporated with
Shortened and Lengthened b Subunits

 FRET. Relatively large insertions and deletions in the tether region of the b

subunit were accommodated by the F1Fo ATP synthase complex and allowed retention of

function (193, 194). Comparing the length of the wild type, shortened and lengthened

peripheral stalks will give some insight on the overall possible conformation of the

altered F1Fo ATP synthase complex. The F1Fo ATP synthase enzyme complex must, in

some way, adapt to the shortened or lengthened b subunits. This can occur in at least one

of two ways: i) distortion of Fl to accommodate the change in length of the peripheral

stalk or ii) distortion of the peripheral stalk itself. If the former was true, Fl could

become distorted by bending of the ye central stalk or compression of the OC3 3 hexamer

and the rigid stalk hypothesis would gain favor. Since F1Fo ATP synthase function

requires the ability of the central stalk to rotate freely while making specific interactions

within the catalytic hexamer, this mechanism is highly unlikely. If the latter situation

were true, distortion would be limited to the b dimer and the flexible stalk hypothesis

would hold true. This could occur by straightening or increasing the naturally occurring