Replication of tobacco mosaic virus VIII. Characterization of a third subgenomic TMV RNA

• Published in: Virology (New York, N.Y.) Vol. 145; no. 1; pp. 132 - 140
• Main Authors: Sulzinski, Michael A., Gabard, Kenneth A., Palukaitis, Peter, Zaitlin, Milton
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.08.1985; Elsevier
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Molecular genetics; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Replication; Systematics. Structure, properties and multiplication. Genetics; Virus; Characterization; Tobamovirus; Virus replication cycle; Replication; Tobacco mosaic virus
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/0042-6822(85)90208-9

In an earlier study we concluded that tobacco mosaic virus (TMV) infections engender a third subgenomic RNA in infected tissue (P. Palukaitis, F. Garcia-Arenal, M. A. Sulzinski, and M. Zaitlin (1983), Virology 131, 533–545). This RNA of approximate MW of 1.1 × 10 6, termed I 1-RNA, was shown to be polyribosome-associated and thus was presumed to serve as a messenger RNA in vivo. Upon in vitro translation of I 1-RNA in a rabbit reticulocyte lysate system, a major product of MW ∼ 50K was generated. When RNA isolated from polyribosomes of infected tissues was analyzed with clones representing distinct regions of the TMV genome, the I 1-RNA was shown to be a subset of the TMV genome, representing the 3′-half of the molecule. A TMV-specific DNA fragment (from a phage M13 clone) containing sequences overlapping the 5′ end of I 1-RNA was used in nuclease S 1-mapping experiments with TMV-RNAs isolated from polyribosomes. I 1-RNA was thus shown to be a distinct RNA species and not a class of heterogeneous molecules of approximately the same size. The I 1-RNA 5′ terminus is residue 3405 in the genome. Based on these findings and on consideration of the TMV-RNA sequence, we propose a model for the translation of I 1-RNA: after an untranslated sequence of 90 bases, an AUG codon at residues 3495–3497 initiates a protein of MW 54K, terminating at residue 4915. Thus, the amino acid sequence of the 54K protein is coincident with those residues of the carboxy terminus of the well-known 183K TMV protein.