The enzyme, found only within a small subset of facultative anaerobic bacteria, belongs to the nonheme diiron family. The enzyme from Salmonella typhimurium was shown to catalyse a stereoselective (E)-hydroxylation at the terminal C4-position of the prenyl group.
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The enzyme appears in viruses and cellular organisms
The enzyme, found only within a small subset of facultative anaerobic bacteria, belongs to the nonheme diiron family. The enzyme from Salmonella typhimurium was shown to catalyse a stereoselective (E)-hydroxylation at the terminal C4-position of the prenyl group.
hydroxylation of the terminal isopentenyl-C4-position is observed with more than 97% E-stereoselectivity. No other nonspecific hydroxylation products are observed in enzymatic assays. The initial rate of MiaE hydroxylation is highly influenced by the substituent at the C2-position of the nucleoside base. MiaE exhibits more than 3fold enhancement for the hydroxylation of the free ms2i6A nucleoside relative to i6A
the diiron active site is buried within the center of the four-alpha-helix bundle. The calculated Fe-Fe distances of 3.19 and 3.24 A are consistent with a diferric state
binding of tRNA to MiaE induces a protein conformational change that influences the electronic structure of the diiron site analogous to what has been observed for various bacterial multicomponent diiron monooxygenases
gene disruption mutants show normal growth characteristics after being shifted from anaerobic to aerobic conditions. Mutants cannot utilize the citric acid cycle intermediates malate, fumarate, and succinate as carbon sources
in mutants of MiaE ms2i6A hydroxylation is blocked. Mutant strains are unable to grow aerobically on the dicarboxylic acids of the citric acid cycle, but have normal uptake of dicarboxylic acids and functional enzymes of the citric acid cycle and the aerobic respiratory chain. 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
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
structure by molecular replacement. MiaE consists of a catalytic diiron(III) domain with a four alpha-helix bundle fold. In the asymmetric unit, two MiaE monomers intertwine to form a homodimer. A narrow and very deep channel runs through the four-alpha-helix bundle from the surface of the protein to the diiron cluster
molecular modeling of structure. MiaE shares the three-dimensional fold with the ferritin-like four-helix bundle proteins and has a similar active site and mechanism of action to diiron carboxylate enzymes
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
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History
1.14.99.69 tRNA 2-(methylsulfanyl)-N6-isopentenyladenosine37 hydroxylase
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