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Relatedness of the double-stranded RNAs present in yeast virus-like particles
Abstract:
The relatedness of several double-stranded RNAs (dsRNA's) present in the virus-like particles of yeast was examined by T1 fingerprint analysis. The dsRNA's examined were L, the dsRNA encoding the capsid polypeptide of yeast virus-like particles; M, which appears to code for a toxic polypeptide and for resistance to the effects of the toxin; and two S dsRNA's present in particles analogous to the defective interfering particles of animal viruses. S3, a dsRNA of 0.46 X 10(6) daltons, was derived entirely from M, a dsRNA of 1.2 X 10(6) daltons. S1, a dsRNA of 0.92 X 10(6) daltons, was a duplication of S3. This conclusion has also been reached independently by heteroduplex mapping techniques (H. M. Fried and G. R. Fink, personal communication). S1 and S3, at least in one yeast strain, were unstable in sequence, apparently due to the accumulation of sequence variants of the same molecular weight. L was a species of 3 X 10(6) daltons, unrelated in sequence to M, S1, or S3. S1, S3, and M had a 3' T1 dodecanucleotide in common.
Insights
Researchers studied yeast virus-like particles
Area of Science:
- Molecular Biology
- Virology
- Yeast Genetics
Background:
- Virus-like particles (VLPs) in yeast contain double-stranded RNA (dsRNA).
- These dsRNAs encode various polypeptides, including capsid proteins and toxins.
- VLPs can contain defective interfering particles analogous to those found in animal viruses.
Purpose of the Study:
- To examine the relatedness of different dsRNAs within yeast virus-like particles.
- To understand the genetic origins and relationships of dsRNA components.
- To investigate the sequence stability of S dsRNAs.
Main Methods:
- T1 fingerprint analysis was used to compare dsRNA sequences.
- Heteroduplex mapping techniques were also employed (as per external communication).
Main Results:
- The L dsRNA (3 x 10^6 daltons) is unrelated to M, S1, or S3 dsRNAs.
- S3 dsRNA (0.46 x 10^6 daltons) is derived from the M dsRNA (1.2 x 10^6 daltons).
- S1 dsRNA (0.92 x 10^6 daltons) is a duplication of S3 dsRNA.
- S1 and S3 dsRNAs exhibit sequence instability due to variant accumulation.
- A common 3' T1 dodecanucleotide was identified in M, S1, and S3 dsRNAs.
Conclusions:
- Yeast VLPs contain distinct dsRNA elements with varying origins and structures.
- The M dsRNA serves as a precursor for the smaller S dsRNAs (S1 and S3).
- Sequence heterogeneity in S dsRNAs suggests ongoing evolutionary or functional adaptation.