Structure and Function of the RNAs of Brome Mosaic Virus

Abstract

Publisher Summary This chapter describes brome mosaic virus (BMV) as a small, multicomponent plant virus. It consists of three virions, designated H, L and M, which contain RNAs 1, 2, and 3-plus-4. RNAs 1, 2, and 4 are monocistronic messengers for proteins of molecular weight approximately 110,000, 105,000 and 20,000; the latter is BMV coat protein. RNA 3 is a dicistronic messenger; it encodes a protein of MW 35,000 and also coat protein. It reviews that all four RNAs are excellent messengers in cell-free extracts derived from wheat embryo. However, only the cistron for the 35,000 MW proteins is translated efficiently by RNA 3. All four RNAs have m 7 GpppG at the 5' terminus, and all four have nearly identical sequences extending for 160 nucleosides from their 3' terminus. The latter region is somewhat resistant to nucleases and can be obtained intact by partial digestion of the RNAs with ribonuclease T1. These 160-nucleoside fragments, as well as the RNAs from which they were obtained, are chargeable with tyrosine in reactions catalyzed by wheat-germ tRNA synthetases.