Molecular analysis of the rolling-circle replicating plasmid pA1 of Lactobacillus plantarum A112.
Lactobacillus plantarum A112 has four different plasmids. Plus-origin-specific probes were used to determine that the smallest, cryptic plasmid, pA1 (2,820 bp), showed homology to the pE194 plasmid family. This subclass of plasmids uses the rolling-circle mode of replication. Subsequent analysis of plasmid pA1 demonstrated that it generates single-stranded DNA intermediates, and sequence analysis revealed that it contains three putative open reading frames (ORFs): ORF1, ORF2, and ORF3, which could encode proteins designated RepA (47 amino acids [aa]) and RepB (196 aa) and a protein of 103 aa, respectively. Two of these proteins, RepA (5.6 kDa) and RepB (26 kDa), were identified in in vitro transcription translation assays. The RepA protein contains a characteristic alpha-helix-turn-alpha-helix motif typical of DNA-binding proteins that act as DNA-binding repressors. The RepB protein shows a significant similarity with replication initiation proteins of the pE194 family of plasmids that use the rolling-circle mode of replication. Plasmid pA1 is able to replicate in Escherichia coli and Lactobacillus lactis subsp. lactis as well as in other L. plantarum strains.
Vujcic
M
M
Institute of Molecular Genetics and Genetic Engineering, Belgrade, Yugoslavia.
Topisirovic
L
L
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D001483:Base Sequence; D004261:DNA Replication; D004269:DNA, Bacterial / Q000032:analysis*; D004270:DNA, Circular / Q000032:analysis*; D004926:Escherichia coli / Q000235:genetics; D007778:Lactobacillus / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000235:genetics / Q000302:isolation & purification; D010957:Plasmids; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004270:DNA, Circular; D010455:Peptides