Poxvirus-induced acid deoxyribonuclease: regulation of synthesis; control of activity in vivo; purification and properties of the enzyme.
Of three nucleases induced by poxvirus, one is a nuclease that acts on denatured DNA at acid pH values. This enzyme has been purified over 3000-fold and has the following characteristics: It degrades heat-denatured DNA exonucleolytically but has negligible activity toward native DNA or RNA; the degradation of denatured DNA is not inhibited by native DNA but is competitively inhibited by sRNA; there is no requirement for added divalent cations; the pH optimum for the degradation of denatured DNA is 4.5, a pH at which the enzyme is insoluble; the enzyme has a K(m) of 7.7 x 10(-6) g and an S(20(o)w) of 5.8 +/- 0.3. There is no detectable enzyme activity with all of these characteristics in uninfected cells. In contrast to the other poxvirus-induced nucleases, the acid nuclease is synthesized under the direction of only progeny DNA templates. During the course of viral infection the enzyme undergoes a sharp transition, in vivo, from a soluble to bound state but is synthesized continuously for about 18 hours postinfection.
McAuslan
B R
BR
Department of Biology, Princeton University, Princeton, New Jersey 08540 USA.
Kates
J R
JR