The mechanism of stimulation of the antiviral factor (AVF) in Nicotiana leaves The involvement of phosphorylation and the role of the N-gene

Abstract

Crude preparations of a precursor of the antiviral factor (pre-AVF) were made from noninfected Nicotiana leaves, either carrying the N-gene or from which the N-gene is absent. These pre-AVF preparations could be activated to give antiviral activity. Crude enzyme preparations, made only from N-gene-carrying plants, but regardless of TMV-infection, served as activating systems. This activation requires ATP, CAMP and cGMP and is associated with the appearance of a new phosphor ylated material seen by polyactylamide gel electrophoresis. The induced antiviral activity has been purified as AVF but was separated from the phosphorylated material. It is proposed that an activating system, determined by the N-gene, is itself being activated through phosphorylation following TMV infection and processes a “pre-AVF” to make active AVE.