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Functional analysis of the Streptomyces ambofaciens element pSAM2
T Smokvina1, F Boccard, Pernodet J-L
1Laboratoire de Biologie et Génétique Moléculaire, URA CNRS D1354, Bât, 400, Université Paris-Sud, Orsay, France.
Plasmid
|January 1, 1991
Summary
The pSAM2 plasmid in Streptomyces facilitates its own replication, integration, and transfer. Researchers mapped its functions, revealing distinct regions for maintenance, transfer, and pock formation.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- pSAM2 is an 11-kb element found in Streptomyces ambofaciens.
- It exists as an integrated element or a free replicon in different strains.
- pSAM2 encodes functions for maintenance, integration, self-transmissibility, pock formation, and marker mobilization.
Purpose of the Study:
- To construct a functional map of the pSAM2 plasmid.
- To delineate regions responsible for plasmid maintenance, transfer, and pock formation.
- To understand the relationship between pSAM2's free form maintenance and its transfer efficiency.
Main Methods:
- Generating deletion and insertion derivatives of pSAM2.
- Introducing pSAM2 derivatives into Streptomyces lividans.
- Analyzing phenotypes of transformants to deduce functional regions.
- Comparing transfer frequencies of wild-type and mutant plasmids.
Main Results:
- Separate genetic regions control pSAM2's free molecule maintenance, transfer, and pock formation.
- Plasmid transfer efficiency is dependent on its ability to be maintained as a free molecule.
- Some deletions were lethal to the plasmid or host, while others allowed transformant recovery when combined.
Conclusions:
- A detailed functional map of pSAM2 was established.
- The study identified distinct genetic determinants for key plasmid functions.
- Understanding these regions is crucial for manipulating Streptomyces plasmids for genetic engineering.