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Large circular and linear rDNA plasmids in Candida albicans.
1Department of Biochemistry and Biophysics, University of Rochester Medical School, Rochester, NY 14642, USA.
Yeast (Chichester, England)
|February 17, 2001
Summary
Candida albicans harbors novel circular and linear rDNA plasmids, a first for this yeast. These extrachromosomal rDNA elements may enhance environmental adaptation by regulating gene copy number.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids carrying ribosomal DNA (rDNA) are common in fungi but previously unreported in Candida species.
- The opportunistic fungal pathogen Candida albicans is a significant human pathogen.
Purpose of the Study:
- To investigate the presence and nature of rDNA plasmids in Candida albicans.
- To characterize the structure and copy number regulation of these plasmids.
Main Methods:
- Plasmid isolation and characterization.
- Analysis of rDNA repeat structures and autonomously replicating sequences (ARS).
- Assessment of plasmid copy number during different growth phases.
Main Results:
- Discovery of two distinct rDNA plasmids in C. albicans: a large circular plasmid and a linear plasmid (50-150 kbp).
- The linear plasmid contains rDNA units, ARSs, and telomeres, with copy number increasing in actively growing cells.
- This study reports the first instance of linear rDNA plasmids in yeast and the co-existence of circular and linear plasmids in C. albicans.
Conclusions:
- The presence of extrachromosomal rDNA, particularly on linear plasmids, may facilitate rapid adaptation to environmental changes in C. albicans.
- These findings represent the first report of naturally occurring plasmids in C. albicans and a novel linear rDNA plasmid in yeast.
- The regulation of rDNA copy number via extrachromosomal elements offers a new perspective on yeast genome plasticity.