1.3.7.6: phycoerythrobilin synthase
This is an abbreviated version!
For detailed information about phycoerythrobilin synthase, go to the full flat file.
Word Map on EC 1.3.7.6
-
1.3.7.6
-
tetrapyrrole
-
cyanobacteria
-
light-harvesting
-
cyanophage
-
phycobiliproteins
-
heme
-
oceanic
-
phycobilisome
-
chromophore
-
fdbrs
-
ferredoxin-dependent
-
open-chain
-
synechococcus
-
myovirus
-
phycobilin
-
antenna
-
metagenomes
-
phycocyanobilin:ferredoxin
-
oxygenase
-
peba
-
prochlorococcus
-
reductases
-
phycocyanobilin
-
algae
- 1.3.7.6
- tetrapyrrole
- cyanobacteria
-
light-harvesting
-
cyanophage
-
phycobiliproteins
- heme
-
oceanic
-
phycobilisome
- chromophore
-
fdbrs
-
ferredoxin-dependent
-
open-chain
- synechococcus
-
myovirus
-
phycobilin
-
antenna
- metagenomes
-
phycocyanobilin:ferredoxin
- oxygenase
-
peba
- prochlorococcus
- reductases
- phycocyanobilin
- algae
Reaction
Synonyms
EBK42635, FDBR, ferredoxin-dependent bilin reductase, PcyX, PEB synthase, PebA, PebB, PebS, PhiPcyX, phycoerythrobilin synthase
ECTree
1.3.7.6 phycoerythrobilin synthaseAdvanced search results
results (
results (General Information
General Information on EC 1.3.7.6 - phycoerythrobilin synthase
Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
top
GENERAL INFORMATION 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
evolution
metabolism
physiological function
the enzyme is involved in the biosynthesis of phycoerythrobilin
additional information
evolution
-
synthesis of linear tetrapyrrole chromophores in cyanobacteria, algae, and plants, ooverview
evolution
-
the enzyme belongs to the ferredoxin-dependent bilin reductase family
evolution
-
ferredoxin-dependent bilin reductases (FDBRs) are a class of enzymes reducing the heme metabolite biliverdin IXa (BV) to form open-chain tetrapyrroles used for light-perception and light-harvesting in photosynthetic organisms. Evolution and molecular mechanism of four-electron reducing ferredoxin-dependent bilin reductases from oceanic phages, overview. PcyX is originally identified from metagenomics data derived from phage. PcyA (EC 1.3.7.2) is the closest relative catalysing the reduction of biliverdin (BV) to phycocyanobilin (PEB). But PcyX converts the same substrate to phycoerythrobilin, resembling the reaction catalysed by cyanophage PebS
evolution
-
ferredoxin-dependent bilin reductases (FDBRs) are a class of enzymes reducing the heme metabolite biliverdin IXa (BV) to form open-chain tetrapyrroles used for light-perception and light-harvesting in photosynthetic organisms. Evolution and molecular mechanism of four-electron reducing ferredoxin-dependent bilin reductases from oceanic phages, overview. PcyX is originally identified from metagenomics data derived from phage. PcyA (EC 1.3.7.2) is the closest relative catalysing the reduction of biliverdin (BV) to phycocyanobilin (PEB). But PcyX converts the same substrate to phycoerythrobilin, resembling the reaction catalysed by cyanophage PebS. The change in regiospecificity from PcyA to PcyX is not only caused by individual catalytic amino acid residues. Rather the combination of the architecture of the active site with the positioning of the substrate triggers specific proton transfer yielding the individual phycobilin products. Phylogenetic analysis and tree suggest PcyX sequences forming a distinct clade
evolution
-
synthesis of linear tetrapyrrole chromophores in cyanobacteria, algae, and plants, ooverview
-
metabolism
-
a two-step reaction via intermediate 15,16-dihydrobiliverdin, the single steps form the reactions of EC 1.3.7.2 and 1.3.7.3, overview
metabolism
phycoerythrobilin (PEB) is an open-chain tetrapyrrole that is derived from heme. The biosynthesis of PEB is, outgoing from heme, mediated by two classes of enzymes: heme oxygenases (HOs) and ferredoxin-dependent bilin reductases (FDBRs). In the first step, HOs (EC: 1.14.99.3) catalyze the ring-opening reaction of the cyclic tetrapyrrole heme at the alpha-mesocarbon bridge, yielding the open-chain tetrapyrrole biliverdin IXalpha (BV), CO and free iron. The sequential reductive cleavage of heme to BV consumes three molecules of O2 and seven electrons. HOs are involved in iron acquisition, oxidative-stress response and pigment biosynthesis. In plants and prokaryotes reduced ferredoxin and ascorbate are able to provide the electrons for the reaction. In the second step, BV is further reduced to PEB by a class of enzymes called ferredoxin-dependent bilin reductases (FDBRs)
additional information
-
aspartate residues Asp105 and Asp206 are both involved in interactions with the pyrrole nitrogens upon substrate binding. Both are essential for the complete reduction of biliverdin IXalpha to (3Z)-phycoerythrobilin by PebS and are highly conserved throughout the family of ferredoxin-dependent bilin reductases
additional information
-
PebS-catalysed PEB synthesis proceeds via a radical mechanism and both aspartate residues involved, Asp105 and Asp206, are important for stereospecific substrate protonation and conversion. Both Asp residues are highly conserved throughout the family of ferredoxin-dependent bilin reductases, bilin radical intermediates during PebS reaction, and superposition of the active site of the wild-type enzyme, the D105N and D206N mutant with bound substrate biliverdin
additional information
-
a conserved aspartate-histidine pair is critical for activity of PcyX. Strutcure comparisons of FDBRs, PcyA and PcyX, overview. Ile86 in PcyA is replaced by Met67, whereas Val90 is substituted by Cys71 in PcyX. Both are strictly conserved in all PcyX sequences, but small hydrophobic residues in all other FDBR. Due to the disorder on the distal side of the binding pocket, residues corresponding to Asn219 in PcyA or to Asp206 in PebS are not visible in our PcyX structure. Modelling of the substrate into the active site. His69 and Asp86 are catalytic important residues, the Asp86/His69 pair of PcyX is critical for catalysis. Also Met67 is crucial for the activity of PcyX, Asn198 is essential for the correct binding of the substrate
additional information
-
the X-ray structure of PhiPcyX (EBK42635) shows the typical alpha/beta/alpha-sandwich fold, with a central antiparallel beta-sheet, flanked by alpha-helices, as described before for other FDBRs. Analysis of the substrate binding pocket structure of PcyX, structure comparisons, overview
