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The internal polyadenylate tract of yeast killer virus M1 double-stranded RNA is variable in length
Abstract:
The 1.8-kbp M1 double-stranded (ds) RNA from type 1 killer strains of Saccharomyces cerevisiae contains an internal 200-bp adenine- and uracil-rich region. We have previously demonstrated that this region consists primarily of adenine residues on the plus strand of M1 dsRNA and on the full-length, in vitro synthesized (+) transcript (denoted m) of M1 dsRNA, neither of which contains 3'-terminal polyadenylate. We now show that there is variability in the length of the polyadenylate tracts of m transcripts synthesized in vitro by virions purified from either of the K1 diploid killer strains A364A X S7 or A364A X 1384. This variability reflects size differences seen in the corresponding M1 dsRNA genomes which, along with other data presented, localizes the variability in the length of M1 dsRNA to the adenine- and uracil-rich region.
Insights
The M1 double-stranded RNA in killer yeast strains has a variable adenine-rich region. This variability in the adenine-rich region directly impacts the M1 dsRNA genome size.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Virology
Background:
- Killer strains of Saccharomyces cerevisiae harbor M1 double-stranded (ds) RNA.
- M1 dsRNA contains an internal adenine- and uracil-rich region.
- Previous studies indicated this region is adenine-rich on the plus strand and its in vitro synthesized transcript (m) lacks 3'-terminal polyadenylate.
Purpose of the Study:
- To investigate the variability in polyadenylate tract lengths of M1 dsRNA transcripts.
- To determine if this variability correlates with M1 dsRNA genome size.
- To localize the source of M1 dsRNA length variation within the genome.
Main Methods:
- In vitro synthesis of M1 (+) transcripts (m) using virions purified from specific killer yeast strains (A364A X S7, A364A X 1384).
- Analysis of polyadenylate tract lengths in synthesized m transcripts.
- Comparison of transcript lengths with M1 dsRNA genome sizes.
Main Results:
- Demonstrated variability in the length of polyadenylate tracts of in vitro synthesized m transcripts.
- Observed that this variability in transcript length corresponds to size differences in the M1 dsRNA genomes.
- Localized the M1 dsRNA length variability to the adenine- and uracil-rich region.
Conclusions:
- The adenine- and uracil-rich region of M1 dsRNA is responsible for variations in its genome length.
- Polyadenylate tract length variability in M1 transcripts is a direct reflection of M1 dsRNA genome size heterogeneity.
- Findings contribute to understanding the structural dynamics of killer yeast dsRNA viruses.