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Structural organization of a cryptic plasmid, pMA1, from Microcystis aeruginosa f. aeruginosa Kützing
H Tominaga1, K Soejima, S Kawagishi
1Laboratory of Applied Biological Science, Faculty of Agriculture, Shimane University, Japan.
Abstract:
The 2287-bp cryptic plasmid, pMA1, from Microcystis aeruginosa f. aeruginosa Kützing, a unicellular cyanobacterium originally derived from Kasumigaura lake, was completely sequenced and analyzed. The predicted amino acid sequence (253 residues) of an open reading frame had identities of 47%, 48%, and 53% with replication-associated proteins of Bacillus amyloliquefaciens's plasmid, pFTB14, B. subtilis BAA1's pBAA1, and B. coagulans's pBC1, respectively, when conservative amino acid substitutions were included. Such high-level identities were also shown with rep proteins and ori regions in a group of Gram-positive bacterial plasmids such as Lactococci and Staphylococci that are known to replicate via single-stranded intermediates. The pMA1 does hybridize with a plasmid, pUS1-3, derived from another unicellular cyanobacterium, Synechocystis sp. PCC 6803. Novel features of pMA1 are discussed.
Insights
The cryptic plasmid pMA1 from Microcystis aeruginosa was sequenced, revealing similarities to replication proteins in Gram-positive bacteria. This cyanobacterial plasmid may replicate via single-stranded intermediates.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Microcystis aeruginosa is a unicellular cyanobacterium known to harbor cryptic plasmids.
- Understanding plasmid biology is crucial for cyanobacterial research and biotechnology.
Purpose of the Study:
- To completely sequence and analyze the cryptic plasmid pMA1 from Microcystis aeruginosa.
- To investigate the genetic features and potential replication mechanisms of pMA1.
Main Methods:
- Complete DNA sequencing of the 2287-bp plasmid pMA1.
- Bioinformatic analysis of open reading frames and predicted protein sequences.
- Hybridization studies with other cyanobacterial plasmids.
Main Results:
- The pMA1 plasmid was fully sequenced and characterized.
- A predicted replication-associated protein showed significant homology (47-53%) to proteins from various Bacillus species.
- Homology extended to rep proteins and ori regions of Gram-positive bacterial plasmids, suggesting single-stranded DNA replication.
- pMA1 hybridized with a plasmid from Synechocystis sp. PCC 6803.
Conclusions:
- The pMA1 plasmid shares genetic features with plasmids from Gram-positive bacteria, indicating potential horizontal gene transfer or conserved replication mechanisms.
- pMA1 likely replicates via single-stranded intermediates, a novel finding for this cyanobacterium.
- Further research into pMA1's novel features could offer insights into cyanobacterial plasmid biology.