T. Suzuki et al., Second stalk of ATP synthase - Cross-linking of gamma subunit in F-1 to truncated F(o)b subunit prevents ATP hydrolysis, J BIOL CHEM, 275(48), 2000, pp. 37902-37906
ATP synthase consists of two portions, F-1 and F-o, connected by two stalks
: a central rotor stalk containing gamma and epsilon subunits and a periphe
ral, second stalk formed by delta and two copies of F(o)b subunits. The sec
ond stalk is expected to keep the stator subunits from spinning along with
the rotor. We isolated a TF1-b'(2) complex (alpha (3)beta (3)gamma delta ep
silonb'(2)) of a thermophilic Bacillus PS3, in which b' was a truncated cyt
oplasmic fragment of F(o)b subunit, and introduced a cysteine at its N term
inus (bc'). Association of b'(2) or bc'(2) with TF1 did not have significan
t effect on ATPase activity. A disulfide bond between the introduced cystei
ne of bc' and cysteine 109 of gamma subunit was readily formed, and this cr
oss-link caused inactivation of ATPase. This implies that F(o)b subunit bou
nd to stator subunits of F-1 with enough strength to resist rotation of gam
ma subunit and to prevent catalysis. Contrary to this apparent tight bindin
g, some detergents such as lauryldodecylamine oxide tend to cause release o
f b'(2) from TF1.