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Characterization of a novel plasmid from extremely halophilic Archaea: nucleotide sequence and function analysis
Xuecheng Ye1, Jianhong Ou, Lina Ni
1Department of Microbiology, Wuhan University, Wuhan 430072, PR China.
FEMS Microbiology Letters
|April 16, 2003
Summary
Researchers sequenced the pHH205 plasmid from Halobacterium salinarum J7, identifying 38 open reading frames and a novel replicon. This haloarchaeal plasmid may be crucial for host growth and useful for vector development.
Area of Science:
- Microbiology
- Molecular Biology
- Genomics
Background:
- Extremely halophilic archaea, such as Halobacterium salinarum, harbor plasmids that play roles in their unique physiology.
- Understanding plasmid biology in halophilic archaea is essential for genetic manipulation and biotechnological applications.
Purpose of the Study:
- To determine the complete nucleotide sequence and genetic organization of the plasmid pHH205 from Halobacterium salinarum J7.
- To identify potential functional elements, including replication origins and protein-coding regions.
- To assess the plasmid's essentiality for the host and its potential utility in molecular biology.
Main Methods:
- Complete nucleotide sequencing of plasmid pHH205.
- Bioinformatic analysis including ORF identification, sequence homology searches, and GC skew analysis.
- Functional analysis by testing a DNA fragment for replication restoration in other archaeal strains.
Main Results:
- The 16,341 bp plasmid pHH205 was fully sequenced, revealing a G+C content of 61.1% and containing 38 large open reading frames (ORFs).
- ORF31 encodes a putative nucleic acid-binding protein with a PIN domain, showing homology to hypothetical proteins in other archaea.
- A specific DNA fragment containing a GC skew-predicted origin of replication and ORF31 restored replication of a deficient plasmid in Haloferax volcanii and H. salinarum R1.
- The plasmid could not be cured from H. salinarum J7, indicating its importance for host growth and metabolism.
Conclusions:
- Plasmid pHH205 represents a novel haloarchaeal replicon with potential applications in constructing cloning and shuttle vectors.
- The identified replication origin and associated protein (ORF31) are key elements for plasmid maintenance and replication in halophilic archaea.
- The essentiality of pHH205 for H. salinarum J7 highlights the intricate relationship between plasmids and host physiology in extreme environments.