Role of Charged Residues in the Catalytic Sites of Escherichia coli ATP Synthase

Table 1

ATPase activity of E. coli membrane bound or purified F₁ enzymes.

Mutationa	ATPase activity μmol/min/mg
Wild-type	28.0 (42.0)
Null	0.0013
βK155Q	(0.023)
βR182K	(0.250)
βR182Q	(0.020)
αR376K	(0.120)
αR376Q	(0.025)
αF291D	0.07
αF291E	0.09
βN243A	0.95
βN243D	0.033
βR246A	0.050 (0.25)
βR246K	(0.27)
βR246Q	(0.27)
βN243R	0.023
βN243R/βR246A	0.016
αF291R	0.035
αF291R/βR246A	0.52
αF291R/βN243R	0.028

aWild-type, pBWU13.4/DK8; Null, pUC118/DK8. All mutants were expressed with the βY331W mutation also present, which does not significantly affect growth. Data are means of four to six experiments each. bMeasured at 37°C and expressed as μmol ATP hydrolyzed/min/mg membrane protein. Each individual experimental point is itself the mean of duplicate assay tubes. Data in parentheses is from purified F₁ ATP synthase. Data taken from [48, 82–84, 86].