<i>In vitro</i>mutagenesis of the putative replicase genes of tobacco mosaic virus

Ishikawa, Masayuki; Meshi, Tetsuo; Motoyoshi, Fusao; Takamatsu, Nobuhiko; Okada, Yoshimi

doi:10.1093/nar/14.21.8291

Cited by 188 publications

(116 citation statements)

References 27 publications

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“…Synthesis of the larger polypeptide results from the translational readthrough of a UAG stop codon, possibly by a tRNA Tyr AUG which has known in vitro suppression activity (Pelham, 1978 ;Beier et al, 1984). This readthrough process is essential for viability of the virus and controls the level of RNA replicase (Ishikawa et al, 1986). The five nucleotides following the stop codon with the consensus sequence UAG CAR YYA, including the cytosine nucleotide immediately 3h to the UAG stop codon, play an important role in readthrough of the TMV stop coding signal, stimulating 2-5 % suppression (Skuzeski & Atkins, 1990 ; Goelet et al, 1982 ;Skuzeski et al, 1991 ; Table 2).…”

Section: Viral and Retrotransposon Stop Codon Suppressionmentioning

confidence: 99%

Endless possibilities: translation termination and stop codon recognition

et al. 2001

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OverviewThe process of protein synthesis can be divided into three main phases : initiation, during which the ribosomal subunits join the mRNA and locate the AUG initiator codon ; elongation, during which sense codons are decoded and the bulk of the polypeptide is made ; and termination, during which a stop codon directs the release of the completed polypeptide from the ribosome. Whereas the general principles of sense codon decoding by transfer RNAs are well established, a clear picture of translation termination and stop codon recognition has hitherto been lacking. Recently however, the use of optimized, complex, reconstituted in vitro termination reactions to identify the roles of key termination factors, and the solution of tertiary structures of termination factors, has allowed a reappraisal of termination factor structure and function. This review will describe these recent advances, many of which have resulted from studies of termination in micro-organisms, and in the light of the new information, discuss models for the mechanism of termination and recognition of the stop codon. While the mechanism of peptide chain termination is normally effective, stop codons are not always recognized efficiently, and during the translation of certain viral RNAs can be suppressed or read through, resulting in the expression of additional coding information. How stop codons are reassigned to encode ' sense ' at a given frequency in some RNAs will be reviewed in the context of current understanding of termination and stop codon recognition mechanisms. The translation termination apparatus in eukaryotes and prokaryotesDuring translation termination, a stop codon located in the ribosomal A-site is recognized by a release factor or release factor complex, which binds the ribosome and triggers release of the nascent peptide. In eukaryotes, translation is terminated by a heterodimer consisting of two proteins, release factors eRF1 and eRF3, which interact in vivo (Frolova et al., 1994 ;Zhouravleva et al., 1995 ;Stansfield et al., 1995). eRF1 recognizes all three stop codons and triggers peptidyl-tRNA hydrolysis by the ribosome, releasing the nascent peptide (Frolova et al., 1994 ; Drugeon et al., 1997). Eukaryote termination efficiency is enhanced by the GTPase release factor eRF3, the second component of the heterodimer eRF complex. In response to a stop codon in the ribosomal A-site, formation of a quaternary complex comprising the ribosome, eRF1, GTP and eRF3 triggers GTP hydrolysis and enhances the rate of peptidyl release (Zhouravleva et al., 1995 ; Frolova et al., 1994 ; Fig. 1). In yeast, eRF1 and eRF3 are encoded by essential genes (SUP35 and SUP45, respectively), mutations in which produce nonsense suppression phenotypes (Stansfield & Tuite, 1994).In contrast to eukaryotes, the role of stop codon recognition during translation termination in eubacteria is divided between two so-called class 1 release factors, RF1 and RF2, which in Escherichia coli are encoded by the essential prfA and prfB genes, respectively (Scolni...

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Section: Viral and Retrotransposon Stop Codon Suppressionmentioning

confidence: 99%

Endless possibilities: translation termination and stop codon recognition

et al. 2001

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“…The suppression of a termination codon is a widespread phenomenon among animal and plant RNA viruses, and is related to the regulation of the expression of the different components of the viral RNA polymerase (Ishikawa et al, 1986;. The fact that the surrounding nucleotide sequences (ATAGCAAT-TACAG) at positions 3420 to 3432 (Fig.…”

Section: Pmmv-s Avvsne S Gltltferpteanvalalqpt I Tskeegslk Ivs Sdvge mentioning

confidence: 99%

Nucleotide Sequence of the Genomic RNA of Pepper Mild Mottle Virus, a Resistance-breaking Tobamovirus in Pepper

Alonso

García-Luque

Cruz

et al. 1991

Journal of General Virology

104

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The entire genomic RNA of a Spanish isolate of pepper mild mottle virus (PMMV-S), a resistance-breaking virus in pepper, was cloned and sequenced and shown to be similar to other tobamoviruses in its genomic organization. It consisted of 6357 nucleotides (nt) and contained four open reading frames (ORFs) which encode a 126K protein and a readthrough 183K protein (nt 70 to 4908), a 28K protein (nt 4909 to 5682) and a 17.5K coat protein (nt 5685 to 6158). This is the first tobamovirus in which none of the ORFs overlap. Both its nucleic acid and predicted protein sequences were compared with the previously determined sequences of other tobamoviruses. The variations and similarities found and their relationship with the pathogenicity of this virus are discussed.

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“…On the other hand, the mutant, in which the amber termination codon of the 130 K protein gene was replaced with a tyrosine codon, which resulted in the production of only the 180 K protein, replicated in tobacco leaves or protoplasts, albeit at a low level of multiplication. 6), 7) This ratio of about 10-20:1) is necessary for the efficient replication of ToMV RNA. On the other hand, the mutant in which the genes for the 30 K protein and CP were deleted replicated normally in tobacco protoplasts.…”

mentioning

confidence: 99%