2-Aminopurine and 5-bromouracil induce alleviation of type I restriction in Escherichia coli: Mismatches function as inducing signals?

Efimova, Elena; Delver, E. P.; Belogurov, A. A.

doi:10.1007/bf00337728

Cited by 24 publications

(22 citation statements)

References 19 publications

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“…Type I restriction is also specifically alleviated in E. coli when the cell's DNA is damaged by agents such as UV radiation (17,46,47) or the base analog 2-aminopurine (22) or when the DNA is unmethylated in dam mutants deficient in adenine methylase activity (21). These findings are associated with the induction of some antirestriction functions in response to DNA damage or modification in cells.…”

Section: Resultsmentioning

confidence: 99%

IncN plasmid pKM101 and IncI1 plasmid ColIb-P9 encode homologous antirestriction proteins in their leading regions

1992

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The IncN plasmid pKM101 (a derivative of R46), like the IncI1 plasmid ColIb-P9, carries a gene (ardA, for alleviation of restriction of DNA) encoding an antirestriction function. ardA was located about 4 kb from the origin of transfer, in the region transferred early during bacterial conjugation. The nucleotide sequence of ardA was determined, and an appropriate polypeptide with the predicted molecular weight of about 19,500 was identified in maxicells of Escherichia coli. Comparison of the deduced amino acid sequences of the antirestriction proteins of the unrelated plasmids pKM101 and ColIb (ArdA and Ard, respectively) revealed that these proteins have about 60% identity. Like ColIb Ard, pKM101 ArdA specifically inhibits both the restriction and modification activities of five type I systems of E. coli tested and does not influence type III (EcoP1) restriction or the 5-methylcytosine-specific restriction systems McrA and McrB. However, in contrast to ColIb Ard, pKM101 ArdA is effective against the type II enzyme EcoRI. The Ard proteins are believed to overcome the host restriction barrier during bacterial conjugation. We have also identified two other genes of pKM101, ardR and ardK, which seem to control ardA activity and ardA-mediated lethality, respectively. Our findings suggest that ardR may serve as a genetic switch that determines whether the ardA-encoded antirestriction function is induced during mating.

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Section: Resultsmentioning

confidence: 99%

IncN plasmid pKM101 and IncI1 plasmid ColIb-P9 encode homologous antirestriction proteins in their leading regions

1992

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“…They are induced when the cell's DNA is damaged by agents such as UV radiation (15) or the base analog 2-aminopurine (18) or when the DNA is unmethylated in dam mutants, which are deficient in adenine methylase activity (17). UV-induced alleviation of restriction seems to be an SOS function (15,41), while others are probably not members of the SOS regulatory network (17,18). Interestingly, one of them, the alleviation function, induced in dam mutants, inhibits both the restriction and modification activities of the EcoK (Type I) system (17) and looks like the ard and 0.3 gene-encoded functions in this respect.…”

Section: Discussionmentioning

confidence: 99%

Nucleotide sequence of the gene (ard) encoding the antirestriction protein of plasmid colIb-P9

Delver¹,

Kotova²,

Zavilgelsky³

et al. 1991

J Bacteriol

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The IncIl plasmid ColIb-P9 was found to encode an antirestriction function. The relevant gene, ard (alleviation of restriction of DNA), maps about 5 kb from the origin of transfer, in the region transferred early during bacterial conjugation. Ard inhibits both restriction and modification by each of the four type I systems of Escherichia coli tested, but it had no effect on restriction by either EcoRI, a type II system, or EcoPl, a type III system. The nucleotide sequence of the ColIb ard gene was determined; the predicted molecular weight of the Ard polypeptide is 19,193. The proposed polypeptide chain contains an excess of 25 negatively charged amino acids, suggesting that its overall character is very acidic. Deletion analysis of the gene revealed that the Ard protein contained a distinct functional domain located in the COOH-terminal half of the polypeptide. We suggest that the biological role of the ColIb Ard protein is associated with overcoming host-controlled restriction during bacterial conjugation.

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“…A temporary loss of restriction proficiency, referred to as restriction alleviation (RA), also occurs in response to treatments that damage DNA (17,38,50,67,177,178). UV light, nalidixic acid, 2-aminopurine (2-AP), and 5-bromouracil have all been shown to induce RA.…”

Section: Host-controlled Modulation Of Restriction Activitymentioning

confidence: 99%

Type I Restriction Systems: Sophisticated Molecular Machines (a Legacy of Bertani and Weigle)

Murray

2000

Microbiol Mol Biol Rev

403

481

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SUMMARY Restriction enzymes are well known as reagents widely used by molecular biologists for genetic manipulation and analysis, but these reagents represent only one class (type II) of a wider range of enzymes that recognize specific nucleotide sequences in DNA molecules and detect the provenance of the DNA on the basis of specific modifications to their target sequence. Type I restriction and modification (R-M) systems are complex; a single multifunctional enzyme can respond to the modification state of its target sequence with the alternative activities of modification or restriction. In the absence of DNA modification, a type I R-M enzyme behaves like a molecular motor, translocating vast stretches of DNA towards itself before eventually breaking the DNA molecule. These sophisticated enzymes are the focus of this review, which will emphasize those aspects that give insights into more general problems of molecular and microbial biology. Current molecular experiments explore target recognition, intramolecular communication, and enzyme activities, including DNA translocation. Type I R-M systems are notable for their ability to evolve new specificities, even in laboratory cultures. This observation raises the important question of how bacteria protect their chromosomes from destruction by newly acquired restriction specifities. Recent experiments demonstrate proteolytic mechanisms by which cells avoid DNA breakage by a type I R-M system whenever their chromosomal DNA acquires unmodified target sequences. Finally, the review will reflect the present impact of genomic sequences on a field that has previously derived information almost exclusively from the analysis of bacteria commonly studied in the laboratory.

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2-Aminopurine and 5-bromouracil induce alleviation of type I restriction in Escherichia coli: Mismatches function as inducing signals?

Cited by 24 publications

References 19 publications

IncN plasmid pKM101 and IncI1 plasmid ColIb-P9 encode homologous antirestriction proteins in their leading regions

IncN plasmid pKM101 and IncI1 plasmid ColIb-P9 encode homologous antirestriction proteins in their leading regions

Nucleotide sequence of the gene (ard) encoding the antirestriction protein of plasmid colIb-P9

Type I Restriction Systems: Sophisticated Molecular Machines (a Legacy of Bertani and Weigle)

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