CUCUMBER MOSAIC-VIRUS RNA-3 - DETERMINATION OF THE NUCLEOTIDE-SEQUENCE PROVIDES THE AMINO-ACID-SEQUENCES OF PROTEIN-3A AND VIRAL COAT PROTEIN

Abstract

The complete sequence of the 2193 residues of RNA 3 (MW 746,000) of cucumber mosaic virus (Q strain) was determined by a combination of chemical and enzymic sequencing techniques utilizing cloned DNA fragments. The nucleotide sequence of RNA 3 also gave the complete sequence of 1027 residues o RNA 4 (MW 349,000), which codes for the viral coat protein and is derived from the 3'' end; there are 53 untranslated nucleotides at the 5'' end of RNA 4. The nucleotide sequence provided the amino acid sequences of the 2 proteins coded for by RNA 3: the 5''-terminal 3A protein with 333 amino acids (MW 36,700) and the 3''-terminal viral coat protein with 236 amino acids (MW 26,200). These 2 coding regions are in the same reading frame, are separated by an intercistronic region of 123 nucleotides and are flanked by 2 untranslated regions of 94 nucleotides at the 5'' terminus and of 263 nucleotides at the 3'' terminus. Secondary structure models are postulated for parts of the RNA 3 sequence. These are considered to be important in the control of the translation and replication of RNA 3 and in the processing of RNA 3 to give RNA 4.