Table 2-1. Aerobic growth properties and membrane-associated ATP hydrolysis activity
 of mutants expressing epitope tagged uncF(b) genes
Strains Description Growth' Specific activity"
KM2/pKAM14 (+) b,,, Apr +++ 1.72 & 0.04
KM2/pBR322 (-) Ab, Apr 0.50 + 0.01
KM2/pTAM3 7 birt-his, Cmr +++ 1.53 & 0.08
KM2/pTAM3 5 b+7-his, Cmr +++ 1.35 & 0.03
KM2/pTAM3 6 birt-HA, Apr +++ 1.48 & 0.03
KM2/pTAM3 4 bA7-HA, Apr +++ 1.39 & 0.04
KM2/pTAM3 7/pTAM3 6 bwt-his + bwt-HA, Cmr & Apr +++ nd
KM2/pTAM3 5/pTAM3 6 b+7-his + bwt-HA, Cmr & Apr +++ nd
KM2/pTAM3 5/pTAM34 b+7-his + bA7-HA, Cmr & Apr +++ 1.41 & 0.04
KM2/pTAM42 birt-his + bwt-HA, Apr +++ nd
KM2/pTAM41 b+7-his + bwt-HA, Apr +++ nd
KM2/pTAM40 b+7-his + bA7-HA, Apr +++ nd
KM2/pTAM46 b,,.-vs, Apr +++ 1.63 & 0.02
KM2/pTAM47 ba7~-vs, Apr +++ 1.40 + 0.05
KM2/pTAM3 7/pTAM46 birt-his + b,,.-VS, Cmr & Apr +++ 1.70 + 0.03
KM2/pTAM3 5/pTAM46 b+7-his + b,,.-VS, Cmr & Apr +++ 1.58 & 0.02
KM2/pTAM3 5/pTAM47 b+7-his + bay7x-s, Cmr & Apr +++ 1.53 & 0.03
 E. coli strains were grown aerobically on succinate minimal medium. Colony size was scored
after 72-hr incubation at 37oC as: +++, 1.0 mm: ++, 0.3-0.5 mm: +, ~0.1 mm: -, no growth.
2 ATPase activities were measured as described under "Materials and Methods." Units
of specific activity = Clmol of PO4 TeleaSed per mg of protein/min & S.D. Units were
calculated from the slope of the line based on three measurements with incubations for 12
minutes.

Effects of epitope tags

 Since Fl has little affinity for the membrane in the absence of intact Fo, total

membrane associated F1-ATP hydrolysis activity was used as a test of F1Fo ATP synthase

complex assembly. Under conditions of high pH, Fl can be released from the influence

of Fo (146), so the amount of ATPase activity in the solution was used as a measure of

the amount of intact enzyme complex located in the membrane vesicles. The histidine

and HA-epitope tags had a slight, but not vitally significant affect on enzyme assembly.

Membrane preparations with a bwt-HA Or bA7-HA inCOrporated into the F1Fo ATP synthase

complex had specific activities of about 86% and 81% of the wild type strain,

respectively (Table 2-1). The latter value was comparable to the effect of the seven