Open AccessAnalysis of pFQ31, a 8551‐bp cryptic plasmid from the symbiotic nitrogen‐fixing actinomycete Frankia
Author(s) -
Lavire Céline,
Louis Dominique,
Perrière Guy,
Briolay Jérome,
Normand Philippe,
Cournoyer Benoit
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb10591.x
Subject(s) - orfs , biology , plasmid , genetics , frankia , replicon , open reading frame , gene , horizontal gene transfer , intergenic region , origin of replication , genome , symbiosis , root nodule , peptide sequence , bacteria
The actinomycete Frankia has never been transformed genetically. To favour the development of Frankia cloning vectors, we have fully sequenced the Frankia alni pFQ31 cryptic plasmid and performed analyses to characterise its coding and non‐coding regions. This plasmid is 8551 bp‐long and contains 72% G+C. Computer‐assisted analyses identified 18 open reading frames (ORFs). These ORFs show a synonymous codon usage different from the one of Frankia chromosomal genes, suggesting an evolutionary bias linked to the nature of the replicon or a horizontal transfer. Three ORFs were found to encode genes likely to be involved in plasmid replication and stability: parFA (partition protein), ptrFA (transcriptional repressor of the GntR family) and repFA (initiation of replication). DNA signatures of a replication origin were identified in the ptrFA – repFA intergenic region. These structural motifs are similar to those observed among origins of iteron‐containing plasmids replicating via a θ mode.