Reaction participants Show >> << Hide
- Name help_outline A Identifier CHEBI:13193 Charge Formula R SMILEShelp_outline * 2D coordinates Mol file for the small molecule Search links Involved in 2,783 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline protoporphyrinogen IX Identifier CHEBI:57307 Charge -2 Formula C34H38N4O4 InChIKeyhelp_outline UHSGPDMIQQYNAX-UHFFFAOYSA-L SMILEShelp_outline Cc1c2Cc3[nH]c(Cc4[nH]c(Cc5[nH]c(Cc([nH]2)c1CCC([O-])=O)c(CCC([O-])=O)c5C)c(C=C)c4C)c(C=C)c3C 2D coordinates Mol file for the small molecule Search links Involved in 8 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline AH2 Identifier CHEBI:17499 Charge 0 Formula RH2 SMILEShelp_outline *([H])[H] 2D coordinates Mol file for the small molecule Search links Involved in 2,713 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline protoporphyrin IX Identifier CHEBI:57306 (Beilstein: 3897489,9313467) help_outline Charge -2 Formula C34H32N4O4 InChIKeyhelp_outline KSFOVUSSGSKXFI-UJJXFSCMSA-L SMILEShelp_outline Cc1c(CCC([O-])=O)c2cc3[nH]c(cc4nc(cc5[nH]c(cc1n2)c(C)c5C=C)c(C)c4C=C)c(C)c3CCC([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 9 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:62000 | RHEA:62001 | RHEA:62002 | RHEA:62003 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Related reactions help_outline
Specific form(s) of this reaction
Publications
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The cyanobacterial protoporphyrinogen oxidase HemJ is a new b-type heme protein functionally coupled with coproporphyrinogen III oxidase.
Skotnicova P., Sobotka R., Shepherd M., Hajek J., Hrouzek P., Tichy M.
Protoporphyrinogen IX oxidase (PPO), the last enzyme that is common to both chlorophyll and heme biosynthesis pathways, catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX. PPO has several isoforms, including the oxygen-dependent HemY and an oxygen-independent enzyme, HemG. Howev ... >> More
Protoporphyrinogen IX oxidase (PPO), the last enzyme that is common to both chlorophyll and heme biosynthesis pathways, catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX. PPO has several isoforms, including the oxygen-dependent HemY and an oxygen-independent enzyme, HemG. However, most cyanobacteria encode HemJ, the least characterized PPO form. We have characterized HemJ from the cyanobacterium <i>Synechocystis</i> sp. PCC 6803 (<i>Synechocystis</i> 6803) as a <i>bona fide</i> PPO; HemJ down-regulation resulted in accumulation of tetrapyrrole precursors and in the depletion of chlorophyll precursors. The expression of FLAG-tagged <i>Synechocystis</i> 6803 HemJ protein (HemJ.f) and affinity isolation of HemJ.f under native conditions revealed that it binds heme <i>b</i> The most stable HemJ.f form was a dimer, and higher oligomeric forms were also observed. Using both oxygen and artificial electron acceptors, we detected no enzymatic activity with the purified HemJ.f, consistent with the hypothesis that the enzymatic mechanism for HemJ is distinct from those of other PPO isoforms. The heme absorption spectra and distant HemJ homology to several membrane oxidases indicated that the heme in HemJ is redox-active and involved in electron transfer. HemJ was conditionally complemented by another PPO, HemG from <i>Escherichia coli.</i> If grown photoautotrophically, the complemented strain accumulated tripropionic tetrapyrrole harderoporphyrin, suggesting a defect in enzymatic conversion of coproporphyrinogen III to protoporphyrinogen IX, catalyzed by coproporphyrinogen III oxidase (CPO). This observation supports the hypothesis that HemJ is functionally coupled with CPO and that this coupling is disrupted after replacement of HemJ by HemG. << Less