Transfer of recombinant plasmids containing the gene for DpnII DNA methylase into strains of Streptococcus pneumoniae that produce DpnI or DpnII restriction endonucleases

Journal Article · Fri Jun 01 04:00:00 EDT 1984 · J. Bacteriol.; (United States)

OSTI ID:5946857

Lacks, S A; Springhorn, S S

Plasmid transfer via the transformation pathway of Streptococcus pneumoniae was weakly restricted by the DpnI or DpnII restriction endonuclease, either of which gave a reduction only to 0.4, compared with phage infection, which was restricted to 10/sup -5/. The greater sensitivity of plasmid transfer compared with chromosomal transformation, which was not at all restricted, can be attributed to partially double-stranded intermediates formed from two complementary donor fragments. However, clustering of potential restriction sites in the plasmids increased the probability of escape from restriction. The recombinant plasmid pMP10, in which the gene for the DpnII DNA methylase was cloned, can be transferred to strains that contain neither restriction enzyme or that contain DpnII as readily as can the vector pMP5. Introduction of pMP10 raised the level of methylase by five times the level normally present in DpnII strains. Transfer of pMP10 to DpnI-containing strains was infrequent, presumably owing to the suicidal methylation of DNA which rendered it susceptible to the host endonuclease. The few clones in which pMP10 was established had lost DpnI. Loss of the plasmid after curing of the cell eliminated the methylase but did not restore DpnI. Although this loss of DpnI could result from spontaneous mutations, its relatively high frequency, 0.1% suggested that the loss was due to a regulatory shift.

• Research Organization: Brookhaven National Lab, Upton, NY
• OSTI ID: 5946857
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 158:3; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

550700* -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
CELL CONSTITUENTS
CHEMICAL REACTIONS
CLONING
DNA
DNA-ASE
ENDONUCLEASES
ENZYME ACTIVITY
ENZYMES
ESTERASES
GENETIC ENGINEERING
HYDROLASES
METHYLATION
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PHOSPHODIESTERASES
PLASMIDS
RECOMBINANT DNA
STREPTOCOCCUS