DpnA, a methylase for single-strand DNA in the Dpn II restriction system, and its biological function

Journal Article · Fri Dec 01 00:00:00 EST 1989 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.86.23.9223· OSTI ID:7138316

Cerritelli, S; Springhorn, S S; Lacks, S A ^[1]

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1. Brookhaven National Lab., Upton, NY (USA)

The two DNA-adenine methylases encoded by the Dpn II restriction gene cassette were purified, and their activities were compared on various DNA substrates. DpnA was able to methylate single-strand DNA and double-strand DNA, whereas DpnM methylated only double-strand DNA. Although both enzymes act at 5{prime}-GATC-3{prime} in DNA, DpnA can also methylate sequences altered in the guanine position, but at a lower rate. A deletion mutation in the dpnA gene was constructed and transferred to the chromosome. Transmission by way of the transformation pathway of methylated and unmethylated plasmids to dpnA mutant and wild-type recipients was examined. The mutant cells restricted unmethylated donor plasmic establishment much more strongly than did wild-type cells. In the wild type, the single strands of donor plasmid DNA that enter by the transformation pathway are apparently methylated by DpnA prior to conversion of the plasmid to a double-strand form, in which the plasmid would be susceptible to the Dpn II endonuclease. The biological function of DpnA may, therefore, be the enhancement of plasmid transfer to Dpn II-containing strains of Streptococcus pneumoniae.

• OSTI ID: 7138316
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 86:23, Issue 23; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ESCHERICHIA COLI
CELL TRANSFORMATIONS
HYDROLASES
GENE MUTATIONS
PLASMIDS
GENE RECOMBINATION
STREPTOCOCCUS
ADENINES
DNA SEQUENCING
GENES
OLIGONUCLEOTIDES
AMINES
ANTIMETABOLITES
AROMATICS
AZAARENES
BACTERIA
CELL CONSTITUENTS
DRUGS
ENZYMES
HETEROCYCLIC COMPOUNDS
MICROORGANISMS
MUTATIONS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PURINES
STRUCTURAL CHEMICAL ANALYSIS
550200* - Biochemistry