Nucleotide sequence ofhemD, the second gene in thehemoperon ofEscherichia coli K-12

Jordan, Peter M.; Mgbeje, B I A; Alwan, Asam F.; Thomas, Steven

doi:10.1093/nar/15.24.10583

Cited by 20 publications

(9 citation statements)

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“…However, several things came together to help permit more detailed studies of this enzyme. The advent of recombinant-DNA technology allowed the enzyme to be produced in much larger quantities (139,140), and the development of a fluorescencebased assay (141) coupled with more accurate high-performance liquid chromatography (HPLC) analysis to separate the type I and III isomers made the assays much more rapid and accurate (142). Consequently, after the initial laborious methods to isolate the first purified UroS enzyme from human blood (143), quite a few UroSs from a variety of organisms were subsequently purified as a consequence of recombinant-DNA approaches (144)(145)(146)(147).…”

Section: Dailey Et Almentioning

confidence: 99%

Prokaryotic Heme Biosynthesis: Multiple Pathways to a Common Essential Product

Dailey

Gerdes³

et al. 2017

Microbiol Mol Biol Rev

273

335

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SUMMARY The advent of heme during evolution allowed organisms possessing this compound to safely and efficiently carry out a variety of chemical reactions that otherwise were difficult or impossible. While it was long assumed that a single heme biosynthetic pathway existed in nature, over the past decade, it has become clear that there are three distinct pathways among prokaryotes, although all three pathways utilize a common initial core of three enzymes to produce the intermediate uroporphyrinogen III. The most ancient pathway and the only one found in the Archaea converts siroheme to protoheme via an oxygen-independent four-enzyme-step process. Bacteria utilize the initial core pathway but then add one additional common step to produce coproporphyrinogen III. Following this step, Gram-positive organisms oxidize coproporphyrinogen III to coproporphyrin III, insert iron to make coproheme, and finally decarboxylate coproheme to protoheme, whereas Gram-negative bacteria first decarboxylate coproporphyrinogen III to protoporphyrinogen IX and then oxidize this to protoporphyrin IX prior to metal insertion to make protoheme. In order to adapt to oxygen-deficient conditions, two steps in the bacterial pathways have multiple forms to accommodate oxidative reactions in an anaerobic environment. The regulation of these pathways reflects the diversity of bacterial metabolism. This diversity, along with the late recognition that three pathways exist, has significantly slowed advances in this field such that no single organism's heme synthesis pathway regulation is currently completely characterized.

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Section: Dailey Et Almentioning

confidence: 99%

Prokaryotic Heme Biosynthesis: Multiple Pathways to a Common Essential Product

Dailey

Gerdes³

et al. 2017

Microbiol Mol Biol Rev

273

335

View full text Add to dashboard Cite

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“…The quantity of enzyme protein isolated was, however, very low in these cases, making detailed structural studies virtually impossible. In order to obtain larger quantities of uroporphyrinogen III synthase we have identified and sequenced, from Escherichia coli, the hemD gene encoding uroporphyrinogen III synthase (Jordan et al, 1987) and have cloned the gene into multi-copy plasmids. This has permitted the generation of recombinant E. coli strains expressing greatly elevated quantities of uroporphyrinogen III synthase.…”

Section: Introductionmentioning

confidence: 99%

Purification and properties of uroporphyrinogen III synthase (co-synthase) from an overproducing recombinant strain of Escherichia coli K-12

Alwan

Mgbeje

Jordan

1989

Biochemical Journal

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The Escherichia coli hemD gene, encoding the enzyme uroporphyrinogen III synthase (co-synthase), was cloned into multi-copy plasmids in E. coli cells that were used to generate strains producing up to 1000 times the concentration of the synthase in the wild-type. The enzyme was purified to homogeneity from these strains in milligram amounts. The enzyme is a monomer of Mr 28,000 with an isoelectric point of 5.2 and a pH optimum of 7.8. The specific activity of the purified synthase is 1500 units/mg and the Km for the substrate, pre-uroporphyrinogen, is 5 microM. The N-terminal sequence of the enzyme is Ser-Ile-Leu-Val-Thr-Arg-Pro-Ser-Pro-Ala-Gly-, in agreement with the gene-derived protein sequence. The enzyme contains four 5,5'-dithiobis-(2-nitrobenzoic acid)-titratable groups, one reacting rapidly with the reagent and three further groups having lower reactivity. The enzyme is heat-sensitive, and during heat inactivation all four thiol groups become equally available for reaction.

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“…hemB (14,30), hemC (65), and hemD (25,55) have been determined. The derived amino acid sequences are very similar to those of the corresponding genes from humans (hemB [71] and hemC [51]) and yeasts (HEM2, i.e., hemB [44]), confirming the conserved nature of the heme biosynthetic pathway from ALA. In B. subtilis, mutations causing ALA or heme auxotrophy have been mapped at two loci.…”

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confidence: 99%

Cloning and characterization of the hemA region of the Bacillus subtilis chromosome

et al. 1990

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A 3.8-kilobase DNA fragment from Bacillus subtilis containing the hemA gene has been cloned and sequenced. Four open reading frames were identified. The first is hemA, encoding a protein of 50.8 kilodaltons. The primary defect of a B. subtilis 5-aminolevulinic acid-requiring mutant was identified as a cysteine-to-tyrosine substitution in the HemA protein. The predicted amino acid sequence of the B. subtilis HemA protein showed 34% identity with the Escherichia coli HemA protein, which is known to code for the NAD(P)H:glutamyl-tRNA reductase of the C5 pathway for 5-aminolevulinic acid synthesis. The B. subtilis HemA protein also complements the defect of an E. coli hemA mutant. The second open reading frame in the cloned fragment, called ORF2, codes for a protein of about 30 kilodaltons with unknown function. It is not the proposed hemB gene product porphobilinogen synthase. The third open reading frame is hemC, coding for porphobilinogen deaminase. The fourth open reading frame extends past the sequenced fragment and may be identical to hemD, coding for uroporphyrinogen III cosynthase. Analysis of deletion mutants of the hemA region suggests that (at least) hemA, ORF2, and hemC may be part of an operon.

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Nucleotide sequence ofhemD, the second gene in thehemoperon ofEscherichia coli K-12

Cited by 20 publications

References 1 publication

Prokaryotic Heme Biosynthesis: Multiple Pathways to a Common Essential Product

Prokaryotic Heme Biosynthesis: Multiple Pathways to a Common Essential Product

Purification and properties of uroporphyrinogen III synthase (co-synthase) from an overproducing recombinant strain of Escherichia coli K-12

Cloning and characterization of the hemA region of the Bacillus subtilis chromosome

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