New 5′ Regions of the Murine and Human Genes for DNA (Cytosine-5)-methyltransferase

doi:10.1074/jbc.271.49.31092

New 5′ Regions of the Murine and Human Genes for DNA (Cytosine-5)-methyltransferase*

From the ^‡ Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, New York 10032 and the
^¶ Johns Hopkins Oncology Center, Johns Hopkins School of Medicine, Baltimore, Maryland 21231

^∥ To whom all correspondence should be addressed:
Dept. of Genetics and Development, Columbia University, 701 W. 168th St., New York, NY 10032.
Tel.: 212-305-5331; Fax: 212-740-0992; E-mail: THB12{at}columbia.edu.

Abstract

DNA (cytosine-5)-methyltransferases (EC 2.1.1.37) maintain patterns of methylated cytosine residues in the mammalian genome; faithful maintenance of methylation patterns is required for normal development of mice, and aberrant methylation patterns are associated with certain human tumors and developmental abnormalities. The organization of coding sequences at the 5′-end of the murine and human DNA methyltransferase genes was investigated, and the DNA methyltransferase open reading frame was found to be longer than previously suspected. Expression of the complete open reading frame by in vitro transcription-translation and by transfection of expression constructs into COS7 cells resulted in the production of an active DNA methyltransferase of the same apparent mass as the endogenous protein, while translation from the second in-frame ATG codon produced a slightly smaller but fully active protein. Characterization of mRNA 5′ sequences and the intron-exon structure of the 5′ region of the murine and human genes indicated that a previously described promoter element (Rouleau, J., Tanigawa, G., and Szyf, M. (1992) J. Biol. Chem. 267, 7368-7377) actually lies in an intron that is more than 5 kilobases downstream of the transcription start sites.

Footnotes

↵^§ The first two authors made equal contributions to this study, and the order of their names is arbitrary.
↵* This work was supported by National Institutes of Health Grants GM00616 and CA60610 (to T. H. B.) and CA43318 (to S. B. B.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) X14805[GenBank], X63692[GenBank].
↵¹ The abbreviations used are:

kb

kilobase(s)

RT-PCR

reverse transcriptase-polymerase chain reaction

RACE

rapid amplification of cDNA ends.
- Received July 3, 1996.