J. Biol. Chem., Vol. 259, Issue 8, 5093-5099, Apr, 1984
A new DNA-dependent ATPase from Escherichia coli. Purification and characterization of ATPase IV
RR Meyer, CL Brown and DC Rein
A new DNA-dependent ATPase named ATPase IV has been purified to apparent
homogeneity from Escherichia coli as a by-product of DNA polymerase III
purification. The enzyme has a specific activity of 360 mumol of ATP
hydrolyzed per min/mg of protein. The purified enzyme exists as monomer
with a molecular weight of 81,000. It sediments in a glycerol gradient as a
single species of 4.5 S. The enzyme has considerable activity at 0 degree C
and has a Q10 of 3.8. In the presence of a DNA effector and magnesium ion,
the enzyme will hydrolyze ATP, dATP, GTP, or dGTP to a nucleoside
diphosphate plus orthophosphate with a Km of 0.20, 0.50, 0.60, and 1.30 mM,
respectively. The guanine nucleotides, however, are only 25-35% as
effective as substrates compared with the adenine nucleotides. ATPase IV
shows strong substrate inhibition by ATP, but not dATP, above 0.2 mM. The
polynucleotide effector requirement can be satisfied by either
single-stranded or double-stranded DNA. The enzyme binds the effector very
tightly with a Km of 3 X 10(-8) M (nucleotide) for G4 DNA. The enzyme is
inhibited by E. coli single-stranded DNA-binding protein, a variety of ATP
analogues and N-ethylmaleimide. The relationship of ATPase IV to DNA
polymerase III holoenzyme is discussed.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
