Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
J Bacteriol. Oct 1994; 176(20): 6255–6261.
PMCID: PMC196966

The Escherichia coli AlkB protein protects human cells against alkylation-induced toxicity.


Escherichia coli can ameliorate the toxic effects of alkylating agents either by preventing DNA alkylation or by repairing DNA alkylation damage. The alkylation-sensitive phenotype of E. coli alkB mutants marks the alkB pathway as an extremely effective defense mechanism against the cytotoxic effects of the SN2, but not the SN1, alkylating agents. Although it is clear that AlkB helps cells to better handle alkylated DNA, no DNA alkylation repair function could be assigned to the purified AlkB protein, suggesting that AlkB either acts as part of a complex or acts to regulate the expression of other genes whose products are directly responsible for alkylation resistance. However, here we present evidence that the provision of alkylation resistance is an intrinsic function of the AlkB protein per se. We expressed the E. coli AlkB protein in two human cell lines and found that it confers the same characteristic alkylation-resistant phenotype in this foreign environment as it does in E. coli. AlkB expression rendered human cells extremely resistant to cell killing by the SN2 but not the SN1 alkylating agents but did not affect the ability of dimethyl sulfate (an SN2 agent) to alkylate the genome. We infer that SN2 agents produce a class of DNA damage that is not efficiently produced by SN1 agents and that AlkB somehow prevents this damage from killing the cell.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.3M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Images in this article

Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Antonucci TK, Wen P, Rutter WJ. Eukaryotic promoters drive gene expression in Escherichia coli. J Biol Chem. 1989 Oct 25;264(30):17656–17659. [PubMed]
  • Banga SS, Boyd JB, Valerie K, Harris PV, Kurz EM, de Riel JK. denV gene of bacteriophage T4 restores DNA excision repair to mei-9 and mus201 mutants of Drosophila melanogaster. Proc Natl Acad Sci U S A. 1989 May;86(9):3227–3231. [PMC free article] [PubMed]
  • Barrows LR, Borchers AH, Paxton MB. Transfectant CHO cells expressing O6-alkylguanine-DNA-alkyltransferase display increased resistance to DNA damage other than O6-guanine alkylation. Carcinogenesis. 1987 Dec;8(12):1853–1859. [PubMed]
  • Blochlinger K, Diggelmann H. Hygromycin B phosphotransferase as a selectable marker for DNA transfer experiments with higher eucaryotic cells. Mol Cell Biol. 1984 Dec;4(12):2929–2931. [PMC free article] [PubMed]
  • Brennand J, Margison GP. Reduction of the toxicity and mutagenicity of alkylating agents in mammalian cells harboring the Escherichia coli alkyltransferase gene. Proc Natl Acad Sci U S A. 1986 Sep;83(17):6292–6296. [PMC free article] [PubMed]
  • Chen J, Derfler B, Maskati A, Samson L. Cloning a eukaryotic DNA glycosylase repair gene by the suppression of a DNA repair defect in Escherichia coli. Proc Natl Acad Sci U S A. 1989 Oct;86(20):7961–7965. [PMC free article] [PubMed]
  • Day RS, 3rd, Babich MA, Yarosh DB, Scudiero DA. The role of O6-methylguanine in human cell killing, sister chromatid exchange induction and mutagenesis: a review. J Cell Sci Suppl. 1987;6:333–353. [PubMed]
  • Harris LC, Margison GP. Expression in mammalian cells of the Escherichia coli O6 alkylguanine-DNA-alkyltransferase gene ogt reduces the toxicity of alkylnitrosoureas. Br J Cancer. 1993 Jun;67(6):1196–1202. [PMC free article] [PubMed]
  • Hayakawa H, Koike G, Sekiguchi M. Expression and cloning of complementary DNA for a human enzyme that repairs O6-methylguanine in DNA. J Mol Biol. 1990 Jun 20;213(4):739–747. [PubMed]
  • Ishizaki K, Tsujimura T, Yawata H, Fujio C, Nakabeppu Y, Sekiguchi M, Ikenaga M. Transfer of the E. coli O6-methylguanine methyltransferase gene into repair-deficient human cells and restoration of cellular resistance to N-methyl-N'-nitro-N-nitrosoguanidine. Mutat Res. 1986 Sep;166(2):135–141. [PubMed]
  • Kaina B, Fritz G, Mitra S, Coquerelle T. Transfection and expression of human O6-methylguanine-DNA methyltransferase (MGMT) cDNA in Chinese hamster cells: the role of MGMT in protection against the genotoxic effects of alkylating agents. Carcinogenesis. 1991 Oct;12(10):1857–1867. [PubMed]
  • Kaina B, Lohrer H, Karin M, Herrlich P. Overexpressed human metallothionein IIA gene protects Chinese hamster ovary cells from killing by alkylating agents. Proc Natl Acad Sci U S A. 1990 Apr;87(7):2710–2714. [PMC free article] [PubMed]
  • Kataoka H, Hall J, Karran P. Complementation of sensitivity to alkylating agents in Escherichia coli and Chinese hamster ovary cells by expression of a cloned bacterial DNA repair gene. EMBO J. 1986 Dec 1;5(12):3195–3200. [PMC free article] [PubMed]
  • Kataoka H, Sekiguchi M. Molecular cloning and characterization of the alkB gene of Escherichia coli. Mol Gen Genet. 1985;198(2):263–269. [PubMed]
  • Kataoka H, Yamamoto Y, Sekiguchi M. A new gene (alkB) of Escherichia coli that controls sensitivity to methyl methane sulfonate. J Bacteriol. 1983 Mar;153(3):1301–1307. [PMC free article] [PubMed]
  • Kondo H, Nakabeppu Y, Kataoka H, Kuhara S, Kawabata S, Sekiguchi M. Structure and expression of the alkB gene of Escherichia coli related to the repair of alkylated DNA. J Biol Chem. 1986 Nov 25;261(33):15772–15777. [PubMed]
  • Lawley PD, Thatcher CJ. Methylation of deoxyribonucleic acid in cultured mammalian cells by N-methyl-N'-nitro-N-nitrosoguanidine. The influence of cellular thiol concentrations on the extent of methylation and the 6-oxygen atom of guanine as a site of methylation. Biochem J. 1970 Feb;116(4):693–707. [PMC free article] [PubMed]
  • Lindahl T, Sedgwick B, Sekiguchi M, Nakabeppu Y. Regulation and expression of the adaptive response to alkylating agents. Annu Rev Biochem. 1988;57:133–157. [PubMed]
  • Rebeck GW, Coons S, Carroll P, Samson L. A second DNA methyltransferase repair enzyme in Escherichia coli. Proc Natl Acad Sci U S A. 1988 May;85(9):3039–3043. [PMC free article] [PubMed]
  • Rebeck GW, Samson L. Increased spontaneous mutation and alkylation sensitivity of Escherichia coli strains lacking the ogt O6-methylguanine DNA repair methyltransferase. J Bacteriol. 1991 Mar;173(6):2068–2076. [PMC free article] [PubMed]
  • Pegg AE. Mammalian O6-alkylguanine-DNA alkyltransferase: regulation and importance in response to alkylating carcinogenic and therapeutic agents. Cancer Res. 1990 Oct 1;50(19):6119–6129. [PubMed]
  • Samson LD. The repair of DNA alkylation damage by methyltransferases and glycosylases. Essays Biochem. 1992;27:69–78. [PubMed]
  • Samson L. The suicidal DNA repair methyltransferases of microbes. Mol Microbiol. 1992 Apr;6(7):825–831. [PubMed]
  • Samson L, Cairns J. A new pathway for DNA repair in Escherichia coli. Nature. 1977 May 19;267(5608):281–283. [PubMed]
  • Samson L, Derfler B, Boosalis M, Call K. Cloning and characterization of a 3-methyladenine DNA glycosylase cDNA from human cells whose gene maps to chromosome 16. Proc Natl Acad Sci U S A. 1991 Oct 15;88(20):9127–9131. [PMC free article] [PubMed]
  • Samson L, Derfler B, Waldstein EA. Suppression of human DNA alkylation-repair defects by Escherichia coli DNA-repair genes. Proc Natl Acad Sci U S A. 1986 Aug;83(15):5607–5610. [PMC free article] [PubMed]
  • Samson L, Linn S. DNA alkylation repair and the induction of cell death and sister chromatid exchange in human cells. Carcinogenesis. 1987 Feb;8(2):227–230. [PubMed]
  • Sedgwick B, Robins P. Isolation of mutants of Escherichia coli with increased resistance to alkylating agents: mutants deficient in thiols and mutants constitutive for the adaptive response. Mol Gen Genet. 1980;180(1):85–90. [PubMed]
  • Shevell DE, Friedman BM, Walker GC. Resistance to alkylation damage in Escherichia coli: role of the Ada protein in induction of the adaptive response. Mutat Res. 1990 Nov-Dec;233(1-2):53–72. [PubMed]
  • Teo I, Sedgwick B, Kilpatrick MW, McCarthy TV, Lindahl T. The intracellular signal for induction of resistance to alkylating agents in E. coli. Cell. 1986 Apr 25;45(2):315–324. [PubMed]
  • Valerie K, de Riel JK, Henderson EE. Genetic complementation of UV-induced DNA repair in Chinese hamster ovary cells by the denV gene of phage T4. Proc Natl Acad Sci U S A. 1985 Nov;82(22):7656–7660. [PMC free article] [PubMed]
  • Valerie K, Green AP, de Riel JK, Henderson EE. Transient and stable complementation of ultraviolet repair in xeroderma pigmentosum cells by the denV gene of bacteriophage T4. Cancer Res. 1987 Jun 1;47(11):2967–2971. [PubMed]
  • Volkert MR, Hajec LI. Molecular analysis of the aidD6::Mu d1 (bla lac) fusion mutation of Escherichia coli K12. Mol Gen Genet. 1991 Oct;229(2):319–323. [PubMed]
  • Volkert MR, Nguyen DC. Induction of specific Escherichia coli genes by sublethal treatments with alkylating agents. Proc Natl Acad Sci U S A. 1984 Jul;81(13):4110–4114. [PMC free article] [PubMed]
  • von Hofe E, Fairbairn L, Margison GP. Relationship between O6-alkylguanine-DNA alkyltransferase activity and N-methyl-N'-nitro-N-nitrosoguanidine-induced mutation, transformation, and cytotoxicity in C3H/10T1/2 cells expressing exogenous alkyltransferase genes. Proc Natl Acad Sci U S A. 1992 Dec 1;89(23):11199–11203. [PMC free article] [PubMed]
  • Yates J, Warren N, Reisman D, Sugden B. A cis-acting element from the Epstein-Barr viral genome that permits stable replication of recombinant plasmids in latently infected cells. Proc Natl Acad Sci U S A. 1984 Jun;81(12):3806–3810. [PMC free article] [PubMed]
  • Xiao W, Samson L. The Saccharomyces cerevisiae MGT1 DNA repair methyltransferase gene: its promoter and entire coding sequence, regulation and in vivo biological functions. Nucleic Acids Res. 1992 Jul 25;20(14):3599–3606. [PMC free article] [PubMed]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...