N-Hydroxyarylamine O-Acetyltransferase-Deficient Escherichia coli Strains Are Resistant to the Mutagenicity of Nitro Compounds

Josephy, P. David; Summerscales, Joanna; DeBruin, Lillian S.; Schlaeger, Christof; Ho, Jason Chen Kok

doi:10.1515/bc.2002.104

Cited by 12 publications

(4 citation statements)

References 27 publications

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“…In bacteria, mutagenic nitroaromatic compounds, such as 2‐nitrofluorene (2‐NF) and 2‐nitro‐3,4‐dimethylimidazo[4,5‐f]quinoline, are reduced to hydroxyarylamines by nitroreductases, then O ‐acetylation of hydroxyarylamines by NhoA yields highly reactive N ‐acetoxy esters, which undergo spontaneous heterolysis, generating DNA adducts . Thus, activity of NhoA is necessary for the mutagenicity of nitroaromatic compounds in bacteria, and previous studies revealed that nhoA ‐deficient bacteria are resistant to the mutagenicity of nitro compounds .…”

Section: Resultsmentioning

confidence: 99%

Reversibly acetylated lysine residues play important roles in the enzymatic activity of Escherichia coli N‐hydroxyarylamine O‐acetyltransferase

Zhou

Gong

et al. 2013

The FEBS Journal

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CobB is a bacterial NAD+‐dependent protein deacetylase. Although progress has been made in functional studies of this protein in recent years, its substrates and biological functions are still largely unclear. Using proteome microarray technology, potential substrates of Escherichia coli CobB were screened and nine proteins were identified, including N‐hydroxyarylamine O‐acetyltransferase (NhoA). In vitro acetylation/deacetylation of NhoA was verified by western blotting and mass spectrometry, and two acetylated lysine residues were identified. Site‐specific mutagenesis experiments showed that mutation of each acetylated lysine decreased the acetylation level of NhoA in vitro. Further analysis showed that variant NhoA proteins carrying substitutions at the two acetylated lysine residues are involved in both the O‐acetyltransferase and N‐acetyltransferase activity of NhoA. Structural analyses were also performed to explore the effects of the acetylated lysine residues on the activity of NhoA. These results suggest that reversible acetylation may play a role in the activity of Escherichia coli NhoA.

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Section: Resultsmentioning

confidence: 99%

Reversibly acetylated lysine residues play important roles in the enzymatic activity of Escherichia coli N‐hydroxyarylamine O‐acetyltransferase

Zhou

Gong

et al. 2013

The FEBS Journal

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“…BLAST analysis based on the amino acid sequences showed that both NhoA1 and NhoA2 belong to the family of N-hydroxyarylamine O-acetyltransferases (NhoAs). Members of the NhoAs have been previously found to catalyze the acetylation of mutagenic and carcinogenic N-hydroxyarylamines that are formed by reduction of nitroarenes or by oxidation of aromatic amines (18,(21)(22)(23)(24). However, whether NhoAs of Enterobacter sp.…”

Section: Discussionmentioning

confidence: 99%

N -Hydroxyarylamine O -Acetyltransferases Catalyze Acetylation of 3-Amino-4-Hydroxyphenylarsonic Acid in the 4-Hydroxy-3-Nitrobenzenearsonic Acid Transformation Pathway of Enterobacter sp. Strain CZ-1

Huang

Gao

et al. 2020

Appl Environ Microbiol

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The organoarsenical feed additive 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone [ROX]) is widely used and released into the environment. We previously showed a two-step pathway of ROX transformation by Enterobacter sp. strain CZ-1 involving the reduction of ROX to 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) and the acetylation of 3-AHPAA to N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA) (K. Huang, H. Peng, F. Gao, Q. Liu, et al., Environ Pollut 247:482–487, 2019, https://doi.org/10.1016/j.envpol.2019.01.076). In this study, we identified two nhoA genes (nhoA1 and nhoA2), encoding N-hydroxyarylamine O-acetyltransferases, as responsible for 3-AHPAA acetylation in Enterobacter sp. strain CZ-1. The results of genetic disruption and complementation showed that both nhoA genes are involved in ROX biotransformation and that nhoA1 is the major 3-AHPAA acetyltransferase gene. Quantitative reverse transcription-PCR analysis showed that the relative expression level of nhoA1 was 3-fold higher than that of nhoA2. Each of the recombinant NhoAs was overexpressed in Escherichia coli BL21 and homogenously purified as a dimer by affinity chromatography. Both purified NhoAs catalyzed acetyl coenzyme A-dependent 3-AHPAA acetylation. The Km values of 3-AHPAA for NhoA1 and NhoA2 were 151.5 and 428.3 μM, respectively. Site-directed mutagenesis experiments indicated that two conserved arginine and cysteine residues of each NhoA were necessary for their enzyme activities. IMPORTANCE Roxarsone (ROX) is an organoarsenic feed additive that has been widely used in poultry industries for growth promotion, coccidiosis control, and meat pigmentation improvement for more than 70 years. Most ROX is excreted in the litter and dispersed into the environment, where it is transformed by microbes into different arsenic-containing compounds. A major product of ROX transformation is N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), which is also used as a clinical drug for treating refractory bacterial vaginosis. Here, we report the cloning and functional characterization of two genes encoding N-hydroxyarylamine O-acetyltransferases, NhoA1 and NhoA2, in Enterobacter sp. strain CZ-1, which catalyze the acetylation of 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) formed by the reduction of ROX to N-AHPAA. This study provides new insights into the function of N-hydroxyarylamine O-acetyltransferase in the transformation of an important organoarsenic compound.

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“…Strain DJ2002 [37] was constructed by PCR-mediated deletion of the nhoA gene, which encodes the endogenous E. coli NAT, and serves as a NAT − control. Strains DJ701 and DJ702 [38] bear plasmid pNM12 [39] and express the Salmonella typhimurium NAT enzyme at high levels.…”

Section: Methodsmentioning

confidence: 99%

Activation of aminoimidazole carcinogens by nitrosation: Mutagenicity and nucleotide adducts

Zenser

Lakshmi

Schut

et al. 2009

Mutation Research/Genetic Toxicology and Environmental Mutagene

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Abstract2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) are heterocyclic amines (HCA) derived from high temperature cooking of meat and thought to cause colon cancer in humans. Reactive nitrogen oxygen species, which are mediators of the inflammatory response, can convert these amines to the corresponding N-nitrosamines, N-NO-IQ and N-NO-MeIQx. This study was designed to evaluate whether these N-nitrosamines are genotoxic and could be responsible, in part, for the high incidence of colon cancer in individuals with colitis. Such an association would counsel reduced intake of well-done red meat by colitis patients. Mutagenicity was evaluated by reversion of a lacZ frameshift allele in three different E. coli strains. Strains DJ701 and DJ702 express recombinant (S. typhimurium) aromatic amine N-acetyltransferase; DJ702 also expresses recombinant human cytochrome P450 1A2 and NADPH-P450 reductase; and DJ2002 served as an N-acetyltransferase-negative control. In strain DJ701, N-NO-IQ and N-NOMeIQx elicited dose-dependent mutagenicity, which was not further increased in DJ702. Neither nitrosamine was mutagenic in strain DJ2002. While both N-nitrosamines are stable for >4 hours (pH 7.4, 37°C), they react with DNA or 2′-deoxyguanosine 3′-monophosphate at lower pH (5.5) to form adducts. HOCl, a component of the inflammatory response, increased adduct formation, as measured by 32 P-postlabeling. Following treatment with nuclease P1 and separation by two-dimensional thinlayer chromatography and then HPLC, N-NO-IQ and N-NO-MeIQx were shown to form the same adducts as those formed by N-OH-MeIQx or N-OH-IQ, namely N-(deoxyguanosin-8-yl) adducts. In summary, these N-nitrosamines are genotoxic and might be alternatives to their hydroxylamine analogues as activated intermediates leading to initiation of colon cancer in individuals with colitis.

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N-Hydroxyarylamine O-Acetyltransferase-Deficient Escherichia coli Strains Are Resistant to the Mutagenicity of Nitro Compounds

Cited by 12 publications

References 27 publications

Reversibly acetylated lysine residues play important roles in the enzymatic activity of Escherichia coli N‐hydroxyarylamine O‐acetyltransferase

Reversibly acetylated lysine residues play important roles in the enzymatic activity of Escherichia coli N‐hydroxyarylamine O‐acetyltransferase

N -Hydroxyarylamine O -Acetyltransferases Catalyze Acetylation of 3-Amino-4-Hydroxyphenylarsonic Acid in the 4-Hydroxy-3-Nitrobenzenearsonic Acid Transformation Pathway of Enterobacter sp. Strain CZ-1

Activation of aminoimidazole carcinogens by nitrosation: Mutagenicity and nucleotide adducts

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