Translation of turnip yellow mosaic virus RNA in vitro: a closed and an open coat protein cistron.

Abstract

Sucrose gradient centrifugation of heat-denatured RNA of turnip yellow mosaic virus permitted the isolation of 5 RNA classes with MW ranging from 2.0-0.25 .times. 106. The infectivity was confined to an RNA molecule of MW 2.0 .times. 106. No significant increase in infectivity was obtained by combination of the latter RNA with the RNA classes of smaller size. Translation in vitro of the RNAs of different size classes in a wheat germ cell-free system revealed that the infectious RNA (MW 2.0 .times. 106) does not promote the synthesis of the coat protein of turnip yellow mosaic virus. Efficient production of this coat protein was found exclusively when the smallest RNA class (MW 250,000) was used as a messenger. RNA molecules of turnip yellow mosaic virus of MW 2.0 .times. 106 apparently contain a closed coat protein cistron and RNA molecules of MW about 2-3 .times. 105 with an open coat protein cistron may be isolated from the virions.