Yeast cells may use AUC or AAG as initiation codon for protein synthesis

Olsen, Ole

doi:10.1007/bf02910430

Cited by 6 publications

(3 citation statements)

References 30 publications

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“…Several recent reports demonstrate the use of a number of non-AUG codons for translation initiation in eukaryotes, especially those that differ from AUG only by a single base substitution (Olsen, 1987;Kozak, 1989a and references therein;Peabody, 1989). Interestingly, ACG and AUA codons can be used as weak start codons for the P gene of duck hepatitis B virus (Schlicht et al, 1989).…”

Section: Discussionmentioning

confidence: 99%

The reverse transcriptase gene of cauliflower mosaic virus is translated separately from the capsid gene.

1990

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Cauliflower mosaic virus (CaMV) Boeke and Corces, 1989;Varmus and Brown, 1989). In general, pol is expressed as a gag-pol fusion protein, e.g. in murine leukemia virus (MLV) by suppression of the gag stop codon (Yoshinaka et al., 1985), in Rous sarcoma virus (RSV), human immunodeficiency virus (HIV-1) and in the yeast retrotransposon Tyl by ribosomal frameshifting within the gaglpol overlapping region (Clare and Farabaugh, 1985;Jacks and Varmus, 1985;Mellor et al., 1985a;Jacks et al., 1988). In mouse mammary tumor virus (MMTV), where gag and pol are separated by another ORF encompassing the protease domain (prt gene), two highly efficient frameshifting events lead to the synthesis of a gag -prt -pol fusion protein (Hizi et al., 1987; Jacks etal., 1987; Moore etal., 1987). In the retrotransposon copia, which contains only a single large Oxford University Press ORF, the ratio of the gag to gag -pol analogues is regulated at the level of RNA splicing (Emori et al., 1985;Miller et al., 1989).The fusion of the RT precursor to the capsid precursor in retroviruses and retrotransposons is thought to provide a means of incorporating RT, by virtue of the gag domain of the fusion protein, into viral or virus-like particles (Witte and Baltimore, 1978). This mechanism apparently directs RT to the specific viral template and sequesters RT from the cytoplasm; it might thereby prevent accidental reverse transcription of cellular RNAs that would be deleterious for the host cell (Baltimore, 1985;Futterer and Hohn, 1987). In fact, the unprocessed gal-pol precursor of retroviruses essentially lacks RT activity when tested with exogenous template, and is activated by proteolytic processing only during or after virion maturation (Witte and Baltimore, 1978;Lu et al., 1979; Traktman and Baltimore, 1982;Panet and Baltimore, 1987;Felsenstein and Goff, 1988).The life cycle of caulimo-and hepadnaviruses is related to that of retroviruses; they replicate via transcription and reverse transcription (for reviews, see Mason et al., 1987; Bonneville et al., 1988). However, unlike retroviruses, reverse transcription probably takes place within immature virions (Summers and Mason, 1982;Marsh et al., 1985) and the mature virions contain DNA rather than RNA. Furthermore, they do not obligatorily integrate into the host genome as proviruses. On the basis of these differences caulimo-and hepadnaviruses have been classified as pararetroviruses (Temin, 1985). Since the open reading frames (ORFs) IV and V, the gag and pol genes of caulimoviruses, as well as the corresponding C and P genes of hepadnaviruses, overlap each other out of frame, and since separate mRNAs have not been identified with certainty, it was originally assumed that they synthesize a capsid-RT fusion protein, too. However, in both these viruses, and in contrast to most retroviruses and retrotransposons, the pol gene analogues have AUG codons within the overlapping region, suggesting that they could be translated independently from the capsid gene. In fact, duck hepatitis B virus...

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Section: Discussionmentioning

confidence: 99%

The reverse transcriptase gene of cauliflower mosaic virus is translated separately from the capsid gene.

1990

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“…This was first observed in bacteria (Looman and van Knippenberg, 1986;Munson etal., 1984;Reddy etal., 1985;Wulff eta/., 1984;Yakota et a/., 1980); with eukaryotic systems, in-witm studies have shown that some triplets are capable of initiating translation at astonishingly high levels (Mehdi et a/., 1990;Peabody, 1987), but these observations depend to a great degree on the precise translation conditions employed and are therefore of dubious physiological significance (Kozak, 1989). Initiation at non-AUG triplets has also been observed in yeast, where it remains very inefficient and of doubtful physiological significance (Clements eta/., 1988;Oonahue and Cigan, 1988;Olsen, 1987;Zitomer eta/., 1984). More recently, such initiation has been observed in mammalian cells (Peabody, 1989).…”

Section: Introductionmentioning

confidence: 99%

Efficient initiation of translation at non‐AUG triplets in plant cells.

1992

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The efficiency of translation initiation at triplets differing at one residue from AUG was tested by transient expression in protoplasts from two different plant species. All possible alternative codons were tested. Some triplets showed significant CAT activity, with CUG (30% of the AUG activity) being most active. Most others had between 5 and 15% of the activity obtained from AUG, whereas UUG and AUC yielded about 2% and the two composed only of purines, AAG and AGG, had no significant activity. Translation initiation from AUC, especially, responded to leader sequences outside the immediate context which did not affect translation initiation from AUG.

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“…An AUC codon within the open reading frame can be used as an alternative initiation codon (Chalut and Egly, 1995). In eukaryotes, a subset of mRNAs also initiate at an AUC codon (Ivanov et al, 2011; Olsen, 1987). Whereas non-AUG initiation has been shown to be remarkably prevalent (Ingolia et al, 2009; Ivanov et al, 2011), the structural basis of recognition of non-AUG initiation codons by the initiator tRNA in the P site is unknown.…”

Section: Introductionmentioning

confidence: 99%

Ribosome Structure Reveals Preservation of Active Sites in the Presence of a P-Site Wobble Mismatch

Svidritskiy

Коростелев

2015

Structure

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Translation initiation in the P site occasionally occurs at atypical (non-AUG) start codons, including those forming a mismatch in the third (wobble) position. During elongation, however, a pyrimidine-pyrimidine wobble mismatch may trigger a translation quality control mechanism, whereby the P-site mismatch is thought to perturb the downstream A-site codon or the decoding center, thereby reducing translation fidelity and inducing termination of aberrant translation. We report a crystal structure of the 70S initiation complex containing an AUC codon in the ribosomal P site. Remarkably, the ribosome stabilizes the mismatched codon-anticodon helix, arranging a normally disruptive cytosine-cytosine pair into a Watson-Crick-like conformation. Translation-competent conformations of the tRNA, mRNA and decoding center suggest that a P-site wobble-position mismatch in the 70S initiation complex does not pre-arrange the mRNA or decoding center to favor subsequent miscoding events.

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Yeast cells may use AUC or AAG as initiation codon for protein synthesis

Cited by 6 publications

References 30 publications

The reverse transcriptase gene of cauliflower mosaic virus is translated separately from the capsid gene.

The reverse transcriptase gene of cauliflower mosaic virus is translated separately from the capsid gene.

Efficient initiation of translation at non‐AUG triplets in plant cells.

Ribosome Structure Reveals Preservation of Active Sites in the Presence of a P-Site Wobble Mismatch

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