Cleavage of the 0-y bond of ATP is required for wild-type (wt) vesicular stomatitis virus transcription in vitro. Recent findings have established that a domain-specific phosphorylation of the virus NS protein is necessary for activity. We report here that RNA synthesis catalyzed by purified standard wt virions responded cooperatively to various ATP concentrations, with half-maximal activity at-500 ,uM. In contrast, mutant po!Rl standard virions and wt defective interfering particles both showed conventional Michaelis-Menten kinetic profiles with K,, values of-143 and-133 ,uM, respectively. The former synthesize readthrough products of the leader-N gene junction in addition to plus-strand leader RNA and mRNAs, whereas the latter synthesize only minus-strand leader RNA. The cooperative response of wt virus products, however, was specific to mRNAs; the small fraction of the total pr6ducts corresponding to plus-strand leader approximated Michaelis-Menten behavior. Since the unique phenotype of the poIR mutants correlates with the synthesis of replicationlike products in vitro, the affected ATP-requjring function most likely regulates both transcription and replication. We suggest that this mutated function involves phosphorylation of viral proteins.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.