Novel catalytic activity associated with positive-strand RNA virus infection: nucleic acid-stimulated ATPase activity of the plum pox potyvirus helicaselike protein.

The cylindrical inclusion protein of potyviruses contains the so-called nucleoside triphosphate binding motif, an amino acid sequence motif present in proteins encoded by most positive-strand RNA viruses, some double-strand RNA viruses, apparently all groups of double-strand DNA viruses, and also several single-strand DNA viruses. Further sequence analysis has allowed to include the cylindrical inclusion protein of potyviruses as a member of a superfamily of helicaselike proteins. In this paper we show that the purified cylindrical inclusion protein of plum pox potyvirus interacts with RNA and ATP and copurifies with a nucleic acid-stimulated ATPase activity. To our knowledge, this is the first time that this kind of enzymatic activity has been experimentally associated with a positive-strand RNA virus-encoded protein.