Format

Send to

Choose Destination
See comment in PubMed Commons below
J Bacteriol. 1988 Apr;170(4):1775-82.

Distribution and diversity of hsd genes in Escherichia coli and other enteric bacteria.

Author information

  • 1Department of Molecular Biology, Edinburgh, United Kingdom.

Abstract

We screened Salmonella typhimurium, Citrobacter freundii, Klebsiella pneumoniae, Shigella boydii, and many isolates of Escherichia coli for DNA sequences homologous to those encoding each of two unrelated type I restriction and modification systems (EcoK and EcoA). Both K- and A-related hsd genes were identified, but never both in the same strain. S. typhimurium encodes three restriction and modification systems, but its DNA hybridized only to the K-specific probe which we know to identify the StySB system. No homology to either probe was detected in the majority of E. coli strains, but in C. freundii, we identified homology to the A-specific probe. We cloned this region of the C. freundii genome and showed that it encoded a functional, A-related restriction system whose specificity differs from those of known type I enzymes. Sequences immediately flanking the hsd K genes of E. coli K-12 and the hsd A genes of E. coli 15T- were shown to be homologous, indicating similar or even identical positions in their respective chromosomes. E. coli C has no known restriction system, and the organization of its chromosome is consistent with deletion of the three hsd genes and their neighbor, mcrB.

PMID:
2832380
PMCID:
PMC211030
[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk