Disease relevance of miaE

• The gene (miaE) for the tRNA(ms2io6A)hydroxylase of S. typhimurium was isolated by complementation in E. coli [1].
• Isolation of the gene (miaE) encoding the hydroxylase involved in the synthesis of 2-methylthio-cis-ribozeatin in tRNA of Salmonella typhimurium and characterization of mutants [1].

High impact information on miaE

• Enzyme preparations from rats pretreated with P-448-dependent aryl hydrocarbon hydroxylase inducers [3-methylcholanthrene (MCA) and beta-naphthoflavone] and MCA-treated "responsive" C57BL mice also metabolized quinoline to a mutagen, but phenobarbital and pregnenolone-16alpha-carbonitrile pretreatment did not yield active preparations [2].
• The activity of 3-MeO-AAB hydroxylase and the amount of cytochrome P-450 in renal microsomes showed a close correlation [3].
• Inhibition of 69% of microsomal aryl hydrocarbon hydroxylase activity by ketoconazole led to partial (10%) inhibition of chromium(V) formation [4].
• Mutants (miaE) of S. typhimurium in which ms2i6A hydroxylation is blocked are unable to grow aerobically on the dicarboxylic acids of the citric acid cycle [5].
• The ability of S. typhimurium to grow on succinate, fumarate, and malate is dependent on the state of modification in position 37 of those tRNAs normally having ms2io6A37 and is not due to a second cellular function of tRNA (ms2io6A37)hydroxylase, the miaE gene product [5].

Biological context of miaE

• Mutants of S. typhimurium which have MudJ inserted in the miaE gene and which, consequently, are blocked in the ms2i6A hydroxylation reaction were isolated [1].
• Its DNA sequence and transcription pattern together with complementation studies revealed that the miaE gene is the second gene of a dicistronic operon [1].
• The most pronounced alterations consisted in a 2.6-fold induction of aryl hydrocarbon hydroxylase in the lung and 8-fold induction of ethoxyresorufin deethylase in the liver, and in a marked stimulation of the liver metabolic activation of all promutagens [6].
• However, any significant correlation between aniline hydroxylase activity and the mutagenesis was not observed [7].

Anatomical context of miaE

• AHH activity and total B[a]P hydroxylase activity were also decreased in these liver microsomes [8].
• The monitored biochemical parameters included aryl hydrocarbon (benzo[a]pyrene) hydroxylase and ethoxyresorufin deethylase in microsomal fractions, epoxide (benzo[a]pyrene-4,5-oxide) hydrolase in both microsomal and cytosolic fractions, glutathione (GSH) and GSH S-transferase in the cytosol [6].

Associations of miaE with chemical compounds

• Both hexane and chloroform extracts could also markedly inhibit the activities of rat liver aniline hydroxylase and aminopyrine demethylase [9].
• In eugenol-treated microsomes, cytochrome P-450 content, AHH activity and total B[a]P hydroxylase activity were decreased to 81, 29 and 48% of the control values, respectively [8].
• This enhancement of mutagenicity does not correlate with arylhydrocarbon hydroxylase activities of the various liver preparations and does not apply to certain other non-PAH mutagens, including beta-naphthylamine, aflatoxin B1 and 4-dimethylaminoazobenzene [10].
• In vitro effects of L-ascorbic acid (vitamin C) on aryl hydrocarbon hydroxylase activity in hepatic microsomes of mice [11].
• New formation of cytochrome P1-450 and the induction aryl hydrocarbon (benzo [a ])pyrene) hydroxylase (as well as numerous other monooxygenase activities) appear to be associated ultimately with genes that cosegregate at a small number of genetic loci [12].

Analytical, diagnostic and therapeutic context of miaE

• Southern blot analysis showed that the miaE gene is absent in E. coli, a finding consistent with the absence of the hydroxylated derivative of ms2i6A in this species [1].
• Parallel to the mutagenicity tests, enzymes of S-9 such as dimethylnitrosamine demethylase and aryl hydrocarbon hydroxylase were estimated and their activity evaluated with reference to the results of the Ames' test [13].

References