Abstract
We have developed a simple new method that can identify the base methylated by a sequence-specific DNA methyltransferase and have used it to identify the cytosine that is methylated by DsaV methyltransferase (M. DsaV) within its recognition sequence 5'-CCNGG. The method utilizes the fact that exonuclease III of E. coli does not degrade DNA ends with 3' overhangs and cannot hydrolyze a phosphorothioate linkage. DNA duplexes containing phosphorothioate linkages at specific positions were methylated with M. DsaV in the presence of [methyl-3H] S-adenosylmethionine and were subjected to exonuclease III digestion. The pattern of [methyl-3H] dCMP release from the duplexes was consistent with the methylation of the internal cytosine in CCNGG, but not of the outer cytosine. To establish the accuracy of this method, we confirmed the known specificity of EcoRII methyltransferase by the method. We also confirmed the specificity of M. DsaV using an established biochemical method that involves the use of a type IIS restriction enzyme. Methylation of CCWGG (W = A or T) sequences at the internal cytosines is native to E. coli and is not restricted by the modified cytosine restriction (Mcr) systems. Surprisingly, the gene for M. DsaV was significantly restricted by the McrBC system. We interpret this to mean that M. DsaV may occasionally methylate at sequences other than CCNGG or may occasionally methylate the outer cytosine in its recognition sequence.
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- Boyer H. W., Chow L. T., Dugaiczyk A., Hedgpeth J., Goodman H. M. DNA substrate site for the EcoRII restriction endonuclease and modification methylase. Nat New Biol. 1973 Jul 11;244(132):40–43. doi: 10.1038/newbio244040a0. [DOI] [PubMed] [Google Scholar]
- Butkus V., Klimasauskas S., Kersulyte D., Vaitkevicius D., Lebionka A., Janulaitis A. Investigation of restriction-modification enzymes from M. varians RFL19 with a new type of specificity toward modification of substrate. Nucleic Acids Res. 1985 Aug 26;13(16):5727–5746. doi: 10.1093/nar/13.16.5727. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Butkus V., Petrauskiene L., Maneliene Z., Klimasauskas S., Laucys V., Janulaitis A. Cleavage of methylated CCCGGG sequences containing either N4-methylcytosine or 5-methylcytosine with MspI, HpaII, SmaI, XmaI and Cfr9I restriction endonucleases. Nucleic Acids Res. 1987 Sep 11;15(17):7091–7102. doi: 10.1093/nar/15.17.7091. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cedar H., Solage A., Glaser G., Razin A. Direct detection of methylated cytosine in DNA by use of the restriction enzyme MspI. Nucleic Acids Res. 1979;6(6):2125–2132. doi: 10.1093/nar/6.6.2125. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Davis R., van der Lelie D., Mercenier A., Daly C., Fitzgerald G. F. ScrFI restriction-modification system of Lactococcus lactis subsp. cremoris UC503: cloning and characterization of two ScrFI methylase genes. Appl Environ Microbiol. 1993 Mar;59(3):777–785. doi: 10.1128/aem.59.3.777-785.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eckstein F. Nucleoside phosphorothioates. Annu Rev Biochem. 1985;54:367–402. doi: 10.1146/annurev.bi.54.070185.002055. [DOI] [PubMed] [Google Scholar]
- Gabbara S., Bhagwat A. S. Interaction of EcoRII endonuclease with DNA substrates containing single recognition sites. J Biol Chem. 1992 Sep 15;267(26):18623–18630. [PubMed] [Google Scholar]
- Gopal J., Yebra M. J., Bhagwat A. S. DsaV methyltransferase and its isoschizomers contain a conserved segment that is similar to the segment in Hhai methyltransferase that is in contact with DNA bases. Nucleic Acids Res. 1994 Oct 25;22(21):4482–4488. doi: 10.1093/nar/22.21.4482. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Karyagina A. S., Lunin V. G., Nikolskaya I. I. Characterization of the genetic determinants of SsoII-restriction endonuclease and modification methyltransferase. Gene. 1990 Mar 1;87(1):113–118. doi: 10.1016/0378-1119(90)90501-h. [DOI] [PubMed] [Google Scholar]
- Koziolkiewicz M., Stec W. J. Application of phosphate-backbone-modified oligonucleotides in the studies on EcoRI endonuclease mechanism of action. Biochemistry. 1992 Oct 6;31(39):9460–9466. doi: 10.1021/bi00154a019. [DOI] [PubMed] [Google Scholar]
- Landry D., Barsomian J. M., Feehery G. R., Wilson G. G. Characterization of type II DNA-methyltransferases. Methods Enzymol. 1992;216:244–259. doi: 10.1016/0076-6879(92)16025-f. [DOI] [PubMed] [Google Scholar]
- Landry D., Looney M. C., Feehery G. R., Slatko B. E., Jack W. E., Schildkraut I., Wilson G. G. M.FokI methylates adenine in both strands of its asymmetric recognition sequence. Gene. 1989 Apr 15;77(1):1–10. doi: 10.1016/0378-1119(89)90353-3. [DOI] [PubMed] [Google Scholar]
- Laue F., Evans L. R., Jarsch M., Brown N. L., Kessler C. A complex family of class-II restriction endonucleases, DsaI-VI, in Dactylococcopsis salina. Gene. 1991 Jan 2;97(1):87–95. doi: 10.1016/0378-1119(91)90013-2. [DOI] [PubMed] [Google Scholar]
- Lauster R., Trautner T. A., Noyer-Weidner M. Cytosine-specific type II DNA methyltransferases. A conserved enzyme core with variable target-recognizing domains. J Mol Biol. 1989 Mar 20;206(2):305–312. doi: 10.1016/0022-2836(89)90480-4. [DOI] [PubMed] [Google Scholar]
- May M. S., Hattaman S. Deoxyribonucleic acid-cytosine methylation by host- and plasmid-controlled enzymes. J Bacteriol. 1975 Apr;122(1):129–138. doi: 10.1128/jb.122.1.129-138.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ohmori H., Tomizawa J. I., Maxam A. M. Detection of 5-methylcytosine in DNA sequences. Nucleic Acids Res. 1978 May;5(5):1479–1485. doi: 10.1093/nar/5.5.1479. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Putney S. D., Benkovic S. J., Schimmel P. R. A DNA fragment with an alpha-phosphorothioate nucleotide at one end is asymmetrically blocked from digestion by exonuclease III and can be replicated in vivo. Proc Natl Acad Sci U S A. 1981 Dec;78(12):7350–7354. doi: 10.1073/pnas.78.12.7350. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pósfai G., Szybalski W. A simple method for locating methylated bases in DNA, as applied to detect asymmetric methylation by M.FokIA. Gene. 1988 Sep 15;69(1):147–151. doi: 10.1016/0378-1119(88)90388-5. [DOI] [PubMed] [Google Scholar]
- Pósfai J., Bhagwat A. S., Pósfai G., Roberts R. J. Predictive motifs derived from cytosine methyltransferases. Nucleic Acids Res. 1989 Apr 11;17(7):2421–2435. doi: 10.1093/nar/17.7.2421. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Raleigh E. A. Organization and function of the mcrBC genes of Escherichia coli K-12. Mol Microbiol. 1992 May;6(9):1079–1086. doi: 10.1111/j.1365-2958.1992.tb01546.x. [DOI] [PubMed] [Google Scholar]
- Raleigh E. A., Wilson G. Escherichia coli K-12 restricts DNA containing 5-methylcytosine. Proc Natl Acad Sci U S A. 1986 Dec;83(23):9070–9074. doi: 10.1073/pnas.83.23.9070. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reich N. O., Olsen C., Osti F., Murphy J. In vitro specificity of EcoRI DNA methyltransferase. J Biol Chem. 1992 Aug 5;267(22):15802–15807. [PubMed] [Google Scholar]
- Rogers S. G., Weiss B. Exonuclease III of Escherichia coli K-12, an AP endonuclease. Methods Enzymol. 1980;65(1):201–211. doi: 10.1016/s0076-6879(80)65028-9. [DOI] [PubMed] [Google Scholar]
- Schlagman S., Hattman S., May M. S., Berger L. In vivo methylation by Escherichia coli K-12 mec+ deoxyribonucleic acid-cytosine methylase protects against in vitro cleavage by the RII restriction endonuclease (R. Eco RII). J Bacteriol. 1976 May;126(2):990–996. doi: 10.1128/jb.126.2.990-996.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Takeuchi M., Lillis R., Demple B., Takeshita M. Interactions of Escherichia coli endonuclease IV and exonuclease III with abasic sites in DNA. J Biol Chem. 1994 Aug 26;269(34):21907–21914. [PubMed] [Google Scholar]
- Wyszynski M. W., Gabbara S., Bhagwat A. S. Substitutions of a cysteine conserved among DNA cytosine methylases result in a variety of phenotypes. Nucleic Acids Res. 1992 Jan 25;20(2):319–326. doi: 10.1093/nar/20.2.319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yebra M. J., Bhagwat A. S. A rapid and sensitive method to measure DNA endonuclease activity. Nucleic Acids Res. 1993 Dec 11;21(24):5797–5798. doi: 10.1093/nar/21.24.5797. [DOI] [PMC free article] [PubMed] [Google Scholar]

