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

Cerritelli, Susana M.; Springhorn, Sylvia S.; Lacks, Sanford A.

doi:10.1073/pnas.86.23.9223

Cited by 58 publications

(44 citation statements)

References 27 publications

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“…Thus it was concluded that ssuMB encoded a second N 6 -methyladenine methyltransferase, which was designated M.SsuMB. The similarities among M.SsuMB, M.DpnA, and M.LlaB suggested that M.SsuMB methylates single-stranded DNA, as described for M.DpnA (8).…”

Section: Resultsmentioning

confidence: 99%

“…The gene encoding a conventional methyltransferase for double-stranded DNA is upstream of the gene encoding a second methyltransferase for single-stranded DNA. The restriction endonuclease gene is downstream and the genes overlap, as seen in the SsuDAT1I genes (8,24,30). In MboI, the order of the genes is different.…”

Section: Discussionmentioning

confidence: 99%

“…However, two of these, DpnII and LlaDCHI, have genes that encode two methyltransferases (8,24,30). A study of well-characterized DpnII and a comparison of it with the LlaDCHI system indicated that in addition to the conventional double-stranded DNA methyltransferase, a single-stranded DNA methyltransferase was encoded, and this activity potentially facilitated the uptake of intact DNA via conjugation in the respective host bacteria.…”

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confidence: 99%

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Evidence for Horizontal Transfer of Ssu DAT1I Restriction-Modification Genes to the Streptococcus suis Genome

et al. 2001

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Different strains of Streptococcus suis serotypes 1 and 2 isolated from pigs either contained a restrictionmodification (R-M) system or lacked it. The R-M system was an isoschizomer of Streptococcus pneumoniae DpnII, which recognizes nucleotide sequence 5-GATC-3. The nucleotide sequencing of the genes encoding the R-M system in S. suis DAT1, designated SsuDAT1I, showed that the SsuDAT1I gene region contained two methyltransferase genes, designated ssuMA and ssuMB, as does the DpnII system. The deduced amino acid sequences of M.SsuMA and M.SsuMB showed 70 and 90% identity to M.DpnII and M.DpnA, respectively. However, the SsuDAT1I system contained two isoschizomeric restriction endonuclease genes, designated ssuRA and ssuRB. The deduced amino acid sequence of R.SsuRA was 49% identical to that of R.DpnII, and R.SsuRB was 72% identical to R.LlaDCHI of Lactococcus lactis subsp. cremoris DCH-4. The four SsuDAT1I genes overlapped and were bounded by purine biosynthetic gene clusters in the following gene order: purF-purMpurN-purH-ssuMA-ssuMB-ssuRA-ssuRB-purD-purE. The G؉C content of the SsuDAT1I gene region (34.1%) was lower than that of the pur region (48.9%), suggesting horizontal transfer of the SsuDAT1I system. No transposable element or long-repeat sequence was found in the flanking regions. The SsuDAT1I genes were functional by themselves, as they were individually expressed in Escherichia coli. Comparison of the sequences between strains with and without the R-M system showed that only the region from 53 bp upstream of ssuMA to 5 bp downstream of ssuRB was inserted in the intergenic sequence between purH and purD and that the insertion target site was not the recognition site of SsuDAT1I. No notable substitutions or insertions could be found, and the structures were conserved among all the strains. These results suggest that the SsuDAT1I system could have been integrated into the S. suis chromosome by an illegitimate recombination mechanism.More than 3,000 restriction-modification (R-M) systems have been identified in a wide variety of microorganisms, where they are thought to protect the host from invasion by foreign DNA. Only a minority of R-M systems have been sequenced (6,37,56). Among them, some type II R-M systems, which recognize 4-bp palindromic sequence 5Ј-GATC-3Ј, involve a variety of isoschizomers. Three classes can be distinguished by their manners of DNA cleavage and susceptibilities to DNA methylation. The first class of isoschizomers, represented by Sau3AI, which was described for Staphylococcus aureus, is prevented from digesting host DNA by a cognate 5-methylcytosine methyltransferase and is not influenced by the modification of N 6 -methyladenine (48, 56). The second class, represented by DpnI, which was described for Streptococcus pneumoniae, is unique among restriction endonucleases in that it cleaves only at methylated DNA sequence 5Ј-GmeATC-3Ј, and thus the cells producing DpnI do not carry the corresponding methyltransferase gene (22,23). The third class, including MboI, DpnII, and LlaDCHI...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Evidence for Horizontal Transfer of Ssu DAT1I Restriction-Modification Genes to the Streptococcus suis Genome

et al. 2001

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“…We propose the designations damA, damB, and damC for SMU.504, SMU.505, and SMU.506, respectively. The DpnM-DpnADpnII (Streptococcus pneumoniae), SsuDAT1IA-SsuDAT1IB-SsuDAT1IC (Streptococcus suis), and the LlaDCHIA-LlaD-CHIB-LlaDCHIC (Lactococcus lactis) systems include a Dam-like methylase that recognizes the nucleotide sequence 5Ј-GATC-3Ј, which is followed by a second methyltransferase that methylates single-stranded DNA, and finally a restriction endonuclease (5,19,23). The Streptococcus sanguinis SsanMASsanMB-SsanRB system is predicted based on its annotated genome sequence (28).…”

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confidence: 99%

Effects of DNA Methylation on Expression of Virulence Genes in Streptococcus mutans

Banas

Biswas

Zhu

2011

Appl Environ Microbiol

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Bacteria produce a variety of enzymes capable of methylating DNA. In many species, the majority of adenine methylation is accomplished by the DNA adenine methylase Dam. In Escherichia coli the Dam methylase plays roles in the initiation of replication, mismatch repair, and gene regulation. In a number of other bacterial species, mutation or overexpression of Dam leads to attenuation of virulence. Homologues of the dam gene exist in some members of the Firmicutes, including Streptococcus mutans, a dental pathogen. An S. mutans strain inactivated in the dam gene (SMU.504; here designated damA) was engineered, and phenotypes linked to cariogenicity were examined. A prominent observation was that the damA mutant produced greater amounts of glucan than the parental strain. Real-time PCR confirmed upregulation of gtfB. To determine whether other loci were affected by the damA mutation, a microarray analysis was carried out. Seventy genes were upregulated at least 2-fold in the damA mutant, and 33 genes were downregulated at least 2-fold. In addition to gtfB (upregulated 2.6-fold; 1.7-fold when measured by real-time PCR), other upregulated virulence factors included gbpC (upregulated 2.1-fold) and loci predicted to encode bacteriocins (upregulated 2-to 7-fold). Various sugar transport operons were also upregulated, the most extreme being the cellobiose operon (upregulated nearly 40-fold). Expression of sacB, encoding fructosyltransferase, was downregulated 2.4-fold. The sequence 5-GATC-3 appeared to constitute the recognition sequence for methylation. These results provide evidence that DNA methylation in S. mutans has a global effect on gene expression, including that of genes associated with cariogenic potential.

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“…Several kinds of R-M systems have been discovered. They seem to do equivalent biological jobs, but in different ways (7,25,36 (9,41). Thus, restriction enzymes destroy foreign DNA segments before they can establish themselves; for example, by recombination into the chromosomal DNA.…”

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confidence: 99%

Isolation of an R- M+ mutant of Yersinia enterocolitica serotype O:8 and its application in construction of rough mutants utilizing mini-Tn5 derivatives and lipopolysaccharide-specific phage

Zhang

Skurnik

1994

J Bacteriol

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

Abstract: 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.

Cited by 58 publications

References 27 publications

Evidence for Horizontal Transfer of Ssu DAT1I Restriction-Modification Genes to the Streptococcus suis Genome

Evidence for Horizontal Transfer of Ssu DAT1I Restriction-Modification Genes to the Streptococcus suis Genome

Effects of DNA Methylation on Expression of Virulence Genes in Streptococcus mutans

Isolation of an R- M+ mutant of Yersinia enterocolitica serotype O:8 and its application in construction of rough mutants utilizing mini-Tn5 derivatives and lipopolysaccharide-specific phage

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