5′-Terminal structure of tobacco rattle virus RNA: Evidence for polarity of reconstitution

Abstract

Purified tobacco rattle virus (TRV) short and long 32P-labeled RNAs (CAM strain) were digested with RNases T 1, T 2, and A. Only short TRV RNA contains a phosphataseresistant 5′-terminal structure, m 7G 5′ppp 5′Ap. Conditions are described in which TRV short and long RNAs are recognized and partially encapsidated by 36 S TRV coat protein. The nucleoprotein complexes contain a lower proportion of RNA than of native TRV. The 5′-terminal end group of TRV short RNA was recognized and encapsidated by TRV protein. Both the lack of reactivity of the 3′-OH end with the protein disk and the electron microscopic observation of only one tail on the nucleoprotein complex argue that the in vitro reconstitution of TRV short particles is a polar process.