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Characterization of Streptomyces plasmid-phage pFP4 and its evolutionary implications
Zhenhua Chen1, Li Zhong, Meijuan Shen
1Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, People's Republic of China.
Plasmid
|June 9, 2012
Summary
A novel plasmid-phage, pFP4, was discovered in Streptomyces sp. FR1 from heavy metal soil. This autonomous-replicating plasmid exhibits phage-like properties, including gene clusters and infectivity, suggesting a unique mobile genetic element.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Heavy metal-contaminated soils harbor diverse microbial communities with unique genetic elements.
- Streptomyces species are known for their genetic plasticity and production of secondary metabolites.
- Plasmids and bacteriophages are key players in horizontal gene transfer and microbial evolution.
Purpose of the Study:
- To characterize the autonomous-replicating plasmid pFP4 from Streptomyces sp. FR1.
- To investigate the genetic makeup and functional properties of pFP4.
- To determine if pFP4 represents a novel type of mobile genetic element.
Main Methods:
- Plasmid isolation, cloning, and DNA sequencing of pFP4.
- Conjugation experiments to assess plasmid transfer.
- Phage infection assays on various Streptomyces strains.
- Transmission electron microscopy (TEM) for visualizing phage particles.
- Analysis of pFP4 gene clusters and DNA cohesive ends.
Main Results:
- The 40,949-bp plasmid pFP4 contains a 20-gene cluster resembling prophages.
- pFP4 demonstrated conjugative transfer and possessed a replication locus (iteron/repA/repB).
- Filtered FR1 culture containing pFP4 formed plaques on susceptible Streptomyces strains, indicating phage-like infectivity.
- TEM confirmed the presence of pFP4 phage particles, with genes encoding major structural proteins.
- pFP4 phage DNA exhibited 3' protruding cohesive ends.
Conclusions:
- Streptomyces sp. FR1 harbors a unique mobile genetic element, the plasmid-phage pFP4.
- pFP4 possesses characteristics of both plasmids (autonomous replication, conjugation) and phages (infectivity, particle formation).
- This discovery expands our understanding of mobile genetic elements in Streptomyces and their potential role in adaptation to contaminated environments.
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