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Biochem J. Feb 15, 2001; 354(Pt 1): 209–215.
PMCID: PMC1221645

Characterization of the Mycobacterium tuberculosis H37Rv alkyl hydroperoxidase AhpC points to the importance of ionic interactions in oligomerization and activity.


An alkyl hydroperoxidase (AhpC) has been found frequently to be overexpressed in isoniazid-resistant strains of Mycobacterium tuberculosis. These strains have an inactivated katG gene encoding a catalase peroxidase, which might render mycobacteria susceptible to the toxic peroxide radicals, thus leading to the concomitant overexpression of the AhpC. Although the overexpressed AhpC in isoniazid-resistant strains of M. tuberculosis may not directly participate in isoniazid action, AhpC might still assist M. tuberculosis in combating oxidative damage in the absence of the catalase. Here we have attempted to characterize the AhpC protein biochemically and report its functional and oligomerization properties. The alkyl hydroperoxidase of M. tuberculosis is unique in many ways compared with its well-characterized homologues from enteric bacteria. We show that AhpC is a decameric protein, composed of five identical dimers held together by ionic interactions. Dimerization of individual subunits takes place through an intersubunit disulphide linkage. The ionic interactions play a significant role in enzymic activity of the AhpC protein. The UV absorption spectrum and three-dimensional model of AhpC suggest that interesting conformational changes may take place during oxidation and reduction of the intersubunit disulphide linkage. In the absence of the partner AhpF subunit in M. tuberculosis, the mycobacterial AhpC might use small-molecule reagents, such as mycothiol, for completing its enzymic cycle.

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Selected References

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  • Zhang Y, Heym B, Allen B, Young D, Cole S. The catalase-peroxidase gene and isoniazid resistance of Mycobacterium tuberculosis. Nature. 1992 Aug 13;358(6387):591–593. [PubMed]
  • Dhandayuthapani S, Zhang Y, Mudd MH, Deretic V. Oxidative stress response and its role in sensitivity to isoniazid in mycobacteria: characterization and inducibility of ahpC by peroxides in Mycobacterium smegmatis and lack of expression in M. aurum and M. tuberculosis. J Bacteriol. 1996 Jun;178(12):3641–3649. [PMC free article] [PubMed]
  • Sherman DR, Mdluli K, Hickey MJ, Arain TM, Morris SL, Barry CE, 3rd, Stover CK. Compensatory ahpC gene expression in isoniazid-resistant Mycobacterium tuberculosis. Science. 1996 Jun 14;272(5268):1641–1643. [PubMed]
  • Storz G, Jacobson FS, Tartaglia LA, Morgan RW, Silveira LA, Ames BN. An alkyl hydroperoxide reductase induced by oxidative stress in Salmonella typhimurium and Escherichia coli: genetic characterization and cloning of ahp. J Bacteriol. 1989 Apr;171(4):2049–2055. [PMC free article] [PubMed]
  • Christman MF, Storz G, Ames BN. OxyR, a positive regulator of hydrogen peroxide-inducible genes in Escherichia coli and Salmonella typhimurium, is homologous to a family of bacterial regulatory proteins. Proc Natl Acad Sci U S A. 1989 May;86(10):3484–3488. [PMC free article] [PubMed]
  • Hillas PJ, del Alba FS, Oyarzabal J, Wilks A, Ortiz De Montellano PR. The AhpC and AhpD antioxidant defense system of Mycobacterium tuberculosis. J Biol Chem. 2000 Jun 23;275(25):18801–18809. [PubMed]
  • Thomas JO. Chemical cross-linking of histones. Methods Enzymol. 1989;170:549–571. [PubMed]
  • Ji TH. Bifunctional reagents. Methods Enzymol. 1983;91:580–609. [PubMed]
  • Riddles PW, Blakeley RL, Zerner B. Ellman's reagent: 5,5'-dithiobis(2-nitrobenzoic acid)--a reexamination. Anal Biochem. 1979 Apr 1;94(1):75–81. [PubMed]
  • Cha MK, Kim IH. Glutathione-linked thiol peroxidase activity of human serum albumin: a possible antioxidant role of serum albumin in blood plasma. Biochem Biophys Res Commun. 1996 May 15;222(2):619–625. [PubMed]
  • Thurman RG, Ley HG, Scholz R. Hepatic microsomal ethanol oxidation. Hydrogen peroxide formation and the role of catalase. Eur J Biochem. 1972 Feb;25(3):420–430. [PubMed]
  • Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. [PubMed]
  • Higgins DG, Sharp PM. CLUSTAL: a package for performing multiple sequence alignment on a microcomputer. Gene. 1988 Dec 15;73(1):237–244. [PubMed]
  • Jones TA, Zou JY, Cowan SW, Kjeldgaard M. Improved methods for building protein models in electron density maps and the location of errors in these models. Acta Crystallogr A. 1991 Mar 1;47(Pt 2):110–119. [PubMed]
  • Kang SW, Baines IC, Rhee SG. Characterization of a mammalian peroxiredoxin that contains one conserved cysteine. J Biol Chem. 1998 Mar 13;273(11):6303–6311. [PubMed]
  • Hirotsu S, Abe Y, Okada K, Nagahara N, Hori H, Nishino T, Hakoshima T. Crystal structure of a multifunctional 2-Cys peroxiredoxin heme-binding protein 23 kDa/proliferation-associated gene product. Proc Natl Acad Sci U S A. 1999 Oct 26;96(22):12333–12338. [PMC free article] [PubMed]
  • Deretic V, Philipp W, Dhandayuthapani S, Mudd MH, Curcic R, Garbe T, Heym B, Via LE, Cole ST. Mycobacterium tuberculosis is a natural mutant with an inactivated oxidative-stress regulatory gene: implications for sensitivity to isoniazid. Mol Microbiol. 1995 Sep;17(5):889–900. [PubMed]
  • Cole ST, Brosch R, Parkhill J, Garnier T, Churcher C, Harris D, Gordon SV, Eiglmeier K, Gas S, Barry CE, 3rd, et al. Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence. Nature. 1998 Jun 11;393(6685):537–544. [PubMed]
  • Wilson TM, Collins DM. ahpC, a gene involved in isoniazid resistance of the Mycobacterium tuberculosis complex. Mol Microbiol. 1996 Mar;19(5):1025–1034. [PubMed]
  • Wilson T, de Lisle GW, Marcinkeviciene JA, Blanchard JS, Collins DM. Antisense RNA to ahpC, an oxidative stress defence gene involved in isoniazid resistance, indicates that AhpC of Mycobacterium bovis has virulence properties. Microbiology. 1998 Oct;144(Pt 10):2687–2695. [PubMed]
  • Jacobson FS, Morgan RW, Christman MF, Ames BN. An alkyl hydroperoxide reductase from Salmonella typhimurium involved in the defense of DNA against oxidative damage. Purification and properties. J Biol Chem. 1989 Jan 25;264(3):1488–1496. [PubMed]
  • Antelmann H, Engelmann S, Schmid R, Hecker M. General and oxidative stress responses in Bacillus subtilis: cloning, expression, and mutation of the alkyl hydroperoxide reductase operon. J Bacteriol. 1996 Nov;178(22):6571–6578. [PMC free article] [PubMed]
  • Chae HZ, Chung SJ, Rhee SG. Thioredoxin-dependent peroxide reductase from yeast. J Biol Chem. 1994 Nov 4;269(44):27670–27678. [PubMed]
  • Niimura Y, Massey V. Reaction mechanism of Amphibacillus xylanus NADH oxidase/alkyl hydroperoxide reductase flavoprotein. J Biol Chem. 1996 Nov 29;271(48):30459–30464. [PubMed]
  • Bornemann C, Jardine MA, Spies HS, Steenkamp DJ. Biosynthesis of mycothiol: elucidation of the sequence of steps in Mycobacterium smegmatis. Biochem J. 1997 Aug 1;325(Pt 3):623–629. [PMC free article] [PubMed]
  • Kitano K, Niimura Y, Nishiyama Y, Miki K. Stimulation of peroxidase activity by decamerization related to ionic strength: AhpC protein from Amphibacillus xylanus. J Biochem. 1999 Aug;126(2):313–319. [PubMed]
  • Schröder E, Littlechild JA, Lebedev AA, Errington N, Vagin AA, Isupov MN. Crystal structure of decameric 2-Cys peroxiredoxin from human erythrocytes at 1.7 A resolution. Structure. 2000 Jun 15;8(6):605–615. [PubMed]
  • Ellis HR, Poole LB. Roles for the two cysteine residues of AhpC in catalysis of peroxide reduction by alkyl hydroperoxide reductase from Salmonella typhimurium. Biochemistry. 1997 Oct 28;36(43):13349–13356. [PubMed]

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