Characterization of pMa025, a plasmid from the cyanobacterium Microcystis aeruginosa UV025
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The characterization of pMa025, a plasmid isolated from the unicellular, toxin-producing cyanobacterium Microcystis aeruginosa UV025, is described. A recombinant plasmid, pMaL [pMa025-pBluescript II SK(–)] was constructed for mapping, sequencing, and development of shuttle vectors capable of transforming both Escherichia coli and M. aeruginosa. pMa025 is 8,018 bp in length and has a G+C content of 62.3 mol%. Nineteen presumptive ORFs, ORF A – ORF S were identified using ATG or GTG as initiation codons. Fifteen different ORFs, ORF a – ORF o were identified using TGA as a degenerate codon for tryptophan. GTG was the start codon in two-thirds of the putative ORFs when TGA was the termination codon. GTG was the start codon in one-third of the putative ORFs when TGA was used as a codon for tryptophan. The deduced amino acid sequence from ORF j (3,114 bp) was significantly similar to that of a putative plasmid replication protein, RepA, from plasmid pUH24 of Synecho coccus sp. strain PCC7942. M. aeruginosa UV027 and E. coli were transformed to carbenicillin resistance with pMaL-D7, a 6.4-kb hybrid plasmid (3.46 kb pMa025, 2.95 kb pBluescript II) generated from the nested deletion strategy. pMaL-D7 will be used as a shuttle vector.
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