Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Combined Automated Annotation using Multiple IEA Methods
UniProtKB entry P32131 (HEMN_ECOLI)
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UniProt records the SAM-dependent EC 1.3.98.3 reaction from PMID:12114526, one [4Fe-4S] cluster coordinated by three cysteines and an exchangeable SAM, a cytoplasmic location and a monomeric subunit structure.
"Reaction=coproporphyrinogen III + 2 S-adenosyl-L-methionine ="
Oxygen-independent coproporphyrinogen-III oxidase HemN from Escherichia coli.
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Recombinant, anaerobically purified HemN is monomeric and converts coproporphyrinogen III to protoporphyrinogen IX in vitro, needing SAM, NAD(P)H and cytoplasmic components.
"The enzyme requires S-adenosyl-l-methionine (SAM), NAD(P)H, and additional cytoplasmatic components for catalysis"
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Cys62, Cys66 and Cys69 are essential for the iron-sulfur cluster and for activity, and mutating the GGGTP SAM-binding motif abolishes activity.
"Mutation of Gly(111) and Gly(113), which are part of the potential GGGTP S-adenosyl-l-methionine binding motif, completely abolished enzymatic function"
Crystal structure of coproporphyrinogen III oxidase reveals cofactor geometry of Radical SAM enzymes.
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The 2.07 A structure of E. coli HemN, the first of any radical SAM enzyme, shows a [4Fe-4S] cluster held by three cysteines, a SAM at the unique iron and a second SAM next to it.
"HemN, strikingly, binds a second SAM immediately adjacent to the first"
Radical S-adenosylmethionine enzyme coproporphyrinogen III oxidase HemN: functional features of the [4Fe-4S] cluster and the two bound S-adenosyl-L-methionines.
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EPR and Mossbauer spectroscopy show a [4Fe-4S] cluster with three cysteine-ligated irons; SAM is a cosubstrate, two SAM are cleaved per protoporphyrinogen IX formed, SAM cleavage depends on substrate, and the second SAM site is needed for catalysis.
"Two molecules of AdoMet were cleaved during one catalytic cycle for the formation of one molecule of protoporphyrinogen IX"
The substrate radical of Escherichia coli oxygen-independent coproporphyrinogen III oxidase HemN.
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EPR with isotopically labelled substrates identifies an allylic coproporphyrinogenyl radical, formed when the 5'-deoxyadenosyl radical abstracts the pro-S beta hydrogen of a propionate side chain.
"this coproporphyrinogenyl radical is allylic and encompasses carbon atoms 3', 3, and 4"
Oxygen-dependent coproporphyrinogen III oxidase (HemF) from Escherichia coli is stimulated by manganese.
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E. coli has two structurally unrelated enzymes for the coproporphyrinogen III step: oxygen-dependent HemF and oxygen-independent HemN.
"two structurally unrelated enzymes, one oxygen-dependent (HemF) and one oxygen-independent (HemN)"
The radical SAM protein HemW is a heme chaperone.
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The HemN sister protein HemW is a heme chaperone rather than a coproporphyrinogen dehydrogenase. In the full text, HemN (not HemW) complemented the anaerobic growth defect of an E. coli hemN deletion strain.
"indicate that the radical SAM protein family HemW/RSAD1 is a heme chaperone"
Radical SAM Enzymes Involved in Tetrapyrrole Biosynthesis and Insertion.
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Review: CgdH (formerly HemN) catalyses the oxidative decarboxylation of coproporphyrinogen III; its two SAMs serve as radical source and radical relay; the related HemW is a heme chaperone.
"the second SAM was shown to act as a radical relay"