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Yeast plasmids resembling 2 micron DNA: regional similarities and diversities at the molecular level
I Utatsu1, S Sakamoto, T Imura
1Department of Fermentation Technology, Hiroshima University, Japan.
Abstract:
The nucleotide sequence of two Zygosaccharomyces plasmids, pSB2 (5,415 base pairs), isolated from Zygosaccharomyces bailii, and pSM1 (5,416 base pairs), isolated from Zygosaccharomyces fermentati Naganishi, was determined. The predicted amino acid sequences of open reading frames among six yeast plasmids that resemble 2 microns DNA indicated regional sequence similarities among FLP proteins. Greater similarities were seen among Zygosaccharomyces plasmids (pSB2, pSB3, pSR1, and pSM1) than other combinations. A putative recognition site for the FLP enzyme of a Zygosaccharomyces plasmid also showed some conservation, especially in the 4 nucleotides flanking the central spacer region. From comparative studies of the sequences of putative genes of each plasmid, we propose an apparent phylogenetic relationship among yeast plasmids resembling 2 micron DNA. Among the Zygosaccharomyces plasmids, pSB2 and pSR1 are most closely related, since not only were the FLP enzymes of these two plasmids most closely related, but also the amino acid sequence of the putative P gene of pSR1 showed clear homology with that of open reading frame B of pSB2.
Insights
This study determined the nucleotide sequences of Zygosaccharomyces plasmids, revealing sequence similarities among FLP proteins and proposing phylogenetic relationships among these yeast plasmids.
Area of Science:
- Yeast genetics
- Molecular biology
- Plasmids
Background:
- Yeast plasmids, such as the 2-micron DNA, play crucial roles in yeast genetics.
- Understanding plasmid sequences and their encoded proteins is essential for yeast biotechnology.
Purpose of the Study:
- To determine the nucleotide sequences of Zygosaccharomyces plasmids pSB2 and pSM1.
- To analyze sequence similarities among open reading frames and FLP proteins.
- To investigate phylogenetic relationships among Zygosaccharomyces plasmids.
Main Methods:
- Nucleotide sequencing of Zygosaccharomyces plasmids pSB2 and pSM1.
- Comparative analysis of predicted amino acid sequences of open reading frames.
- Identification of FLP enzyme recognition sites.
Main Results:
- The nucleotide sequences of pSB2 (5,415 bp) and pSM1 (5,416 bp) were determined.
- Regional sequence similarities were observed among FLP proteins from six yeast plasmids resembling 2-micron DNA.
- Zygosaccharomyces plasmids (pSB2, pSB3, pSR1, pSM1) exhibited greater FLP protein sequence similarities compared to other combinations.
- A conserved FLP enzyme recognition site was identified in Zygosaccharomyces plasmids.
- The P gene of pSR1 showed homology to open reading frame B of pSB2, indicating close relatedness.
Conclusions:
- The study proposes an apparent phylogenetic relationship among yeast plasmids resembling 2-micron DNA based on comparative sequence analysis.
- pSB2 and pSR1 are identified as the most closely related Zygosaccharomyces plasmids due to high FLP enzyme and P gene sequence homology.