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Pulsed-field electrophoresis indicates larger-than-expected sizes for mycoplasma genomes
L E Pyle1, L N Corcoran, B G Cocks
1Russell Grimwade School of Biochemistry, University of Melbourne, Parkville, Victoria, Australia.
Abstract:
The sizes of large DNA fragments produced from genomes of members of the Mycoplasmataceae by digestion with restriction endonucleases having infrequent (1 to 3) cleavage sites within the genome were estimated from their mobility in contour-clamped homogeneous electric field (CHEF) agarose gel electrophoresis by comparison with yeast chromosomal DNA markers. The estimates of total genome size for 7 strains of 6 species ranged from approximately 900 kilo base pairs (kb) for Ureaplasma urealyticum 960T to 1330 kb for M. mycoides subsp. mycoides, GC-1176. The values derived from this new method are considerably higher than those of approximately 500 Mdaltons or 750 kb previously reported for genome sizes in members of the Mycoplasmataceae.
Insights
This study estimates Mycoplasmataceae genome sizes using contour-clamped homogeneous electric field (CHEF) electrophoresis. Results reveal significantly larger genomes than previously reported, ranging up to 1330 kb.
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Mycoplasmataceae are bacteria with small genomes, but their exact sizes are debated.
- Previous genome size estimations for Mycoplasmataceae may have underestimated their true size.
Purpose of the Study:
- To accurately determine the genome sizes of various Mycoplasmataceae species.
- To establish a more reliable method for estimating large DNA fragment sizes in these bacteria.
Main Methods:
- Utilized contour-clamped homogeneous electric field (CHEF) agarose gel electrophoresis.
- Employed yeast chromosomal DNA markers for accurate size comparison.
- Digested genomic DNA with restriction endonucleases with infrequent cleavage sites.
Main Results:
- Genome size estimates for 7 strains across 6 species ranged from 900 kb (Ureaplasma urealyticum) to 1330 kb (M. mycoides subsp. mycoides).
- These estimations are substantially higher than previously reported sizes (approx. 750 kb).
Conclusions:
- Mycoplasmataceae possess larger genomes than previously understood.
- CHEF electrophoresis provides a more accurate method for determining Mycoplasmataceae genome sizes.