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Structural and functional analysis of two cryptic plasmids from Lactobacillus pentosus MD353 and Lactobacillus plantarum ATCC 8014

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Author: Leer, R.J. · Luijk, N. van · Posno, M. · Pouwels, P.H.
Institution: Medisch Biologisch Laboratorium TNO
Source:Molecular and General Genetics, 2, 234, 265-274
Identifier: 231795
Keywords: DNA sequence analysis · Lactobacillus plasmids · Rolling circle replication · Segregational stability · Amino acid sequence · Bacterium · Lactobacillus · Nonhuman · Nucleotide sequence · Plasmid · Priority journal · Amino Acid Sequence · Bacteriophage lambda · Base Sequence · DNA Replication · DNA, Bacterial · DNA, Viral · Escherichia coli · Lactobacillus · Molecular Sequence Data · Nucleic Acid Conformation · Plasmids · Repetitive Sequences, Nucleic Acid · Support, Non-U.S. Gov't · Transformation, Bacterial


The DNA sequences of a 2.4 kb plasmid (p353-2) from Lactobacillus pentosus MD353 and a 1.9 kb plasmid (p8014-2) from Lactobacillus plantarum ATCC 8014 show 81.5% overall similarity. Both plasmids carry elements (replication protein gene, plus-origin and minus-origin of replication), which are typical of plasmids that replicate via a rolling-circle mechanism of replication (RCR). Direct evidence for an RCR mechanism was obtained by showing the accumulation of single-stranded plasmid intermediates in the presence of rifampicin. A minus-origin of replication was defined for plasmids p353-2 and p8014-2 based on DNA sequence analysis and on its ability to convert single-stranded into double-stranded plasmid DNA. Plasmids pLPE323, pLPE350 and pLPC37 that are derived from the p353-2 or p8014-2 replicon are structurally and segregationally stable in L. pentosus MD353, L. plantarum ATCC 8014 and in Lactobacillus casei ATCC 393. The presence of Escherichia coli or λ DNA fragments in vectors derived from p353-2 or p8013-2 does not affect the structural stability but results in segregational instability of the vectors. The instability increases with increasing size of the inserted DNA fragment. Since vectors based on these replicons can be effciently propagated in a wide variety of Lactobacillus species, they are highly suitable for cloning and expression of foreign DNA in Lactobacillus, provided that selective pressure is applied.