Genetic analysis and complete nucleotide sequence of a 2-kb cryptic plasmid from the marine methylotroph Methylophaga thalassica S1.
A small cryptic plasmid (pMTS1) was isolated from the marine methylotroph Methylophaga thalassica S1. Sequence analysis showed that pMTS1 has a 1995-bp genome encoding three putative polypeptides and containing two intergenic regions. The longest open reading frame encodes a polypeptide of 325 amino acid (37,079 Da). This polypeptide shares similarity and signature amino acids with the rep proteins of the pC194 group replicons, suggesting that pMTS1 replicates by the rolling-cycle mechanism. Insertional mutagenesis confirmed that the repA gene product is obligatory for replication of pMTS1 in M. thalassica S1. A pC194-type dso was identified in the second intergenic area. It appears that this intergenic region contains both the nic and bind sites. It is hypothesized that sso of pMTS1 is located in the first intergenic region. Two smaller open reading frames (orf-1 and orf-2) encode transcriptionally coupled polypeptides of 123 and 101 amino acids (14,486 and 11,241 Da, respectively) with unknown biological function.
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Marine Sciences Research Center, State University of New York at Stony Brook, Stony Brook, New York 11794-5000, USA. andrei@notes.cc.sunysb.edu
D000595:Amino Acid Sequence; D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis*; D020563:Gammaproteobacteria / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000032:analysis*; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial