Alkyl hydroperoxide reductase is the primary scavenger of endogenous hydrogen peroxide in Escherichia coli

被引:646
作者
Seaver, LC [1 ]
Imlay, JA [1 ]
机构
[1] Univ Illinois, Dept Microbiol, Urbana, IL 61801 USA
关键词
D O I
10.1128/JB.183.24.7173-7181.2001
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
Hydrogen peroxide is generated during aerobic metabolism and is capable of damaging critical biomolecules. However, mutants of Escherichia coli that are devoid of catalase typically exhibit no adverse phenotypes during growth in aerobic media. We discovered that catalase mutants retain the ability to rapidly scavenge H2O2 whether it is formed internally or provided exogenously. Analysis of candidate genes revealed that the residual activity is due to alkyl hydroperoxide reductase (Ahp). Mutants that lack both Ahp and catalase could not scavenge H2O2. These mutants excreted substantial amounts of H2O2, and they grew poorly in air. Ahp is kinetically a more efficient scavenger of trace H2O2 than is catalase and therefore is likely to be the primary scavenger of endogenous H2O2. Accordingly, mutants that lack Ahp accumulated sufficient hydrogen peroxide to induce the OxyR regulon, whereas the OxyR regulon remained off in cataIase mutants. Catalase still has an important role in wild-type cells, because the activity of Ahp is saturated at a low (10(-5) M) concentration of H2O2. In contrast, cataIase has a high K-m, and it therefore becomes the predominant scavenger when H2O2 concentrations are high. This arrangement is reasonable because the cell cannot provide enough NADH for Ahp to rapidly degrade large amounts of H2O2. In sum, E. coli does indeed generate substantial H2O2, but damage is averted by the scavenging activity of Ahp.
引用
收藏
页码:7173 / 7181
页数:9
相关论文
共 33 条
[1]  
BIELSKI BHJ, 1983, J BIOL CHEM, V258, P4759
[2]   Mutation of the Bacillus subtilis alkyl hydroperoxide reductase (ahpCF) operon reveals compensatory interactions among hydrogen peroxide stress genes [J].
Bsat, N ;
Chen, L ;
Helmann, JD .
JOURNAL OF BACTERIOLOGY, 1996, 178 (22) :6579-6586
[3]   ISOLATION OF SUPEROXIDE-DISMUTASE MUTANTS IN ESCHERICHIA-COLI - IS SUPEROXIDE-DISMUTASE NECESSARY FOR AEROBIC LIFE [J].
CARLIOZ, A ;
TOUATI, D .
EMBO JOURNAL, 1986, 5 (03) :623-630
[4]   NONENZYMATIC DECARBOXYLATION OF PYRUVATE [J].
CONSTANTOPOULOS, G ;
BARRANGER, JA .
ANALYTICAL BIOCHEMISTRY, 1984, 139 (02) :353-358
[5]   Oxidative stress defense and deterioration of growth-arrested Escherichia coli cells [J].
Dukan, S ;
Nyström, T .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (37) :26027-26032
[6]  
GAUDU P, 1994, J BIOL CHEM, V269, P8182
[7]   Homeostatic regulation of intracellular hydrogen peroxide concentration in aerobically growing Escherichia coli [J].
GonzalezFlecha, B ;
Demple, B .
JOURNAL OF BACTERIOLOGY, 1997, 179 (02) :382-388
[8]  
GONZALEZFLECHA B, 1905, J BIOL CHEM, P13681
[9]   Modulation of the activities of catalase-peroxidase HPI of Escherichia coli by site-directed mutagenesis [J].
Hillar, A ;
Peters, B ;
Pauls, R ;
Loboda, A ;
Zhang, HM ;
Mauk, AG ;
Loewen, PC .
BIOCHEMISTRY, 2000, 39 (19) :5868-5875
[10]  
IMLAY JA, 1991, J BIOL CHEM, V266, P6957