Helicobacter pylori interstrain restriction-modification diversity prevents genome subversion by chromosomal DNA from competing strains

Rahul A. Aras, Aaron J. Small, Takafumi Ando, Martin J. Blaser

Research output: Contribution to journalReview articlepeer-review

51 Scopus citations

Abstract

Helicobacter pylori, bacteria that colonize the human gastric mucosa, possess a large number of genes for restriction-modification (R-M) systems, and essentially, every strain possesses a unique complement of functional and partial R-M systems. Nearly half of the H.pylori strains studied possess an active type IIs R-M system, HpyII, with the recognition sequence GAAGA. Recombination between direct repeats that flank the R-M cassette allows for its deletion whereas strains lacking hpyIIRM can acquire this cassette through natural transformation. We asked whether strains lacking HpyII R-M activity can acquire an active hpyIIRM cassette [containing a 1.4 kb kanamycin resistance (aphA) marker], whether such acquisition is DNase sensitive or resistant and whether restriction barriers limit acquisition of chromosomal DNA. Our results indicate that natural transformation and conjugation-like mechanisms may contribute to the transfer of large (4.8 kb) insertions of chromosomal DNA between H.pylori strains, that inactive or partial R-M systems can be reactivated upon recombination with a functional allele, consistent with their being contingency genes, and that H.pylori R-M diversity limits acquisition of chromosomal DNA fragments of ≥1 kb.

Original languageEnglish (US)
Pages (from-to)5391-5397
Number of pages7
JournalNucleic acids research
Volume30
Issue number24
DOIs
StatePublished - Dec 15 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics

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