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The replication origin of Azotobacter vinelandii
R A Singh1, N R Choudhury, H K Das
1Genetic Engineering Unit, Jawaharlal Nehru University, New Delhi, India.
Molecular & General Genetics : MGG
|February 5, 2000
Summary
Researchers identified a 200-bp DNA fragment from Azotobacter vinelandii that functions as a replication origin. This fragment enables autonomous replication in E. coli, revealing unique characteristics distinct from other known bacterial origins.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacterial DNA replication origins are crucial for cell division and genetic stability.
- Understanding replication origins in diverse bacteria like Azotobacter vinelandii is essential for comparative genomics.
Purpose of the Study:
- To clone and characterize the putative replication origin of Azotobacter vinelandii.
- To determine the minimal DNA fragment required for autonomous replication.
- To analyze the sequence and features of the identified origin.
Main Methods:
- Ligation of Azotobacter vinelandii DNA to an antibiotic resistance cartridge.
- Plasmid isolation, Southern hybridization, and electron microscopy.
- Cloning and sequencing of DNA fragments in E. coli.
- Polymerase Chain Reaction (PCR) amplification and direct sequencing.
Main Results:
- A 200-bp DNA fragment from A. vinelandii was identified as sufficient for autonomous replication in an E. coli polA strain.
- Replication initiation was localized within this A. vinelandii fragment.
- The sequence analysis revealed unique features and variations from consensus DnaA binding sites.
- The origin fragment was found in other Azotobacter spp. field strains.
Conclusions:
- A novel replication origin from Azotobacter vinelandii has been characterized.
- This origin possesses distinct sequence features compared to other known bacterial origins.
- The identified origin is conserved across different Azotobacter species.