Affiliation:
1. Unité 65, Faculté de Médecine, Institut National de la Santé et de la Recherche Médicale, Nîmes, France.
Abstract
Analysis of the entire Agrobacterium tumefaciens C58 genome by pulsed-field gel electrophoresis (PFGE) reveals four replicons: two large molecules of 3,000 and 2,100 kb, the 450-kb cryptic plasmid, and the 200-kb Ti plasmid. Digestion by PacI or SwaI generated 12 or 14 fragments, respectively. The two megabase-sized replicons, used as probes, hybridize with different restriction fragments, showing that these replicons are two independent genetic entities. A 16S rRNA probe and genes encoding functions essential to the metabolism of the organism were found to hybridize with both replicons, suggesting their chromosomal nature. In PFGE, megabase-sized circular DNA does not enter the gel. The 2.1-Mb chromosome always generated an intense band, while the 3-Mb band was barely visible. After linearization of the DNA by X-irradiation, the intensity of the 3-Mb band increased while that of the 2.1-Mb remained constant. This suggests that the 3-Mb chromosome is circular and that the 2.1-Mb chromosome is linear. To confirm this hypothesis, genomic DNA, trapped in an agarose plug, was first submitted to PFGE to remove any linear DNA present. The plug was then recovered, and the remaining DNA was digested with either PacI or SwaI and then separated by PFGE. The fragments corresponding to the small chromosome were found to be absent, while those corresponding to the circular replicon remained, further proof of the linear nature of the 2.1-Mb chromosome.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference37 articles.
1. Physical map of the Brulcella melitensis 16M chromosome;Allardet-Servent A.;J. Bacteriol.,1991
2. Allardet-Servent A. S. Michaux-Charachon and M. Ramuz. 1993. Agrobacterium tumefaciens C58 contains one circular and one linear chromosome. Presented at the First International Symposium Mapping and Sequencing of Small Genomes 28 to 30 March 1993 Institut Pasteur Paris France.
3. Biology of Borrelia species;Barbour A.;Microbiol. Rev.,1986
4. Linear chromosome of Borrelia burgdorferi;Baril C.;Res. Microbiol.,1989
5. Physical characterization of Rhizobium meliloti megaplasmids;Burkhardt B.;Plasmid,1987
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