Cited by 66Bacterial Genetics and BiotechnologyProbiotics and Fermented FoodsBacteriophages and microbial interactions

Sequence Analysis of Two Cryptic Plasmids from Bifidobacterium longum DJO10A and Construction of a Shuttle Cloning Vector

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Lee, Ju-Hoon, O’Sullivan, Daniel J.·2006·Applied and Environmental Microbiology

Abstract

Bifidobacterium longum DJO10A is a recent human isolate with probiotic characteristics and contains two plasmids, designated pDOJH10L and pDOJH10S. The complete sequences of both these plasmids have now been determined and consist of two circular DNA molecules of 10,073 and 3,661 bp, with G+C contents of 62.2% and 66.2%, respectively. Plasmid pDOJH10L is a cointegrate plasmid consisting of DNA regions exhibiting very high sequence identity to two other B. longum plasmids, pNAC2 (98%) and pKJ50 (96%), together with another region. Interestingly, the rolling circular replication (RCR) regions of both the pNAC2- and pKJ50-like plasmids were disrupted during the recombination event leading to a further recombination event to acquire a functional replicon. This consists of a new fused rep gene and an RCR-type ori consisting of a conserved DnaA box in an AT-rich region followed by four contiguous repeated sequences consistent with an iteron structure and an inverted repeat. The smaller pDOJH10S had no sequence similarity to any other characterized plasmid from bifidobacteria. In addition, it did not contain any features consistent with RCR, which is the replication mechanism proposed for all the bifidobacteria plasmids characterized to date. It did exhibit sequence similarity with several theta replication-related replication proteins from other gram-positive, high-G+C bacteria, with the closest match from a Rhodococcus rhodochrous plasmid, suggesting a theta mechanism of replication. S1 nuclease analysis of both plasmids in B. longum DJO10A revealed single-strand DNA intermediates for pDOJH10L, which is consistent for RCR, but none were detected for pDOJH10S. As the G+C content of pDOJH10S is similar to that of Rhodococcus rhodochrous (67%) and significantly higher than that of B. longum (60.1%), it may have been acquired through horizontal gene transfer from a Rhodococcus species, as both genera are members of the Actinomycetes and are intestinal inhabitants. An Escherichia coli-B. longum shuttle cloning vector was constructed from pDOJH10S and the E. coli ori region of p15A, a lacZ gene with a multiple cloning site of pUC18, and a chloramphenicol resistance gene (CAT) of pCI372 and was transformed successfully into E. coli and B. longum . It could not be introduced into lactic acid bacteria ( Lactococcus and Lactobacillus ), showing it was not very promiscuous. It was stably maintained in B. longum in the absence of antibiotic pressure for 92 generations, which is consistent with the segregational stability of theta-replicating plasmids in gram-positive bacteria. This is the first cloning vector for bifidobacteria that does not utilize RCR and should be useful for the stable introduction of heterologous genes into these dominant inhabitants of the large intestine.

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Crossref · 10.1128/aem.72.1.527-535.2006

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Authors
Lee, J.-H., & O’Sullivan, D. J.
Affiliations
University of Minnesota (US)
Corresponding author
O’Sullivan, Daniel J.
Venue
Applied and Environmental Microbiology
Published
2006-01
Volume
72
Issue
1
Pages
527-535
ISSN
  • 0099-2240 (ISSN-L)
  • 1098-5336
OpenAlex
W2166899061
Cited by
66
References
47
Citations by year
2026: 2 · 2025: 1 · 2024: 1 · 2022: 2 · 2021: 2 · 2017: 3 · 2016: 1 · 2015: 6 · 2014: 2 · 2013: 6 · 2012: 8
FWCI
4.17
Type
journal article
Language
en
Open access
Locations
  • Applied and Environmental Microbiology (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Bacterial Genetics and Biotechnology
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Probiotics and Fermented Foods
  • Physical Sciences › Environmental Science › Ecology › Bacteriophages and microbial interactions
Keywords
Bifidobacterium longum, cryptic plasmid, plasmid sequence analysis, rolling circle replication, theta replication, plasmid replication origin, rep gene, horizontal gene transfer, Rhodococcus rhodochrous, probiotic bacteria, plasmid recombination, GC content, single-stranded DNA
MeSH terms
Amino Acid Sequence, Base Sequence, Bifidobacterium, Escherichia coli, Genetic Techniques, Genetic Vectors, Humans, Molecular Sequence Data, Plasmids, Sequence Analysis, DNA, Electroporation

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