ABSTRACT
This chapter describes some chemical reactions of satellite RNA of tobacco ringspot virus (STobRV RNA) STobRV RNA and related RNAs that have been observed in vitro. It suggests that the unusual reactions have a role in replication of STobRV RNA. The "RNA-level" infectious agents are viroids and certain small satellite RNAs, such as those of the nepoviruses and of sobemoviruses. Electrophoretically purified dimeric RNA preparations gradually accumulated RNA with the mobility of monomeric form, implying nonenzymic, autolytic processing. Cleavage at a specific site within a specific sequence, i.e., at an autolytic junction, is an important criterion for distinguishing authentic autolytic processing from less precise nuclease-catalyzed, or chemical, degradation of an RNA molecule. An autolytic processing reaction that is at least superficially similar to that of STobRV (+)RNA is exhibited by the bacteriophage T4 RNA p2Spl. Prody et al. reported the nonenzymic ligation of monomeric STobRV (+) RNA to generate dimers in a yield of less than 1%.
