Literature summary for 1.3.7.3 extracted from

Aras, M.; Hartmann, V.; Hartmann, J.; Nowaczyk, M.M.; Frankenberg-Dinkel, N.
Proximity channeling during cyanobacterial phycoerythrobilin synthesis (2020), FEBS J., 287, 284-294 .

Search for more literature for 1.3.7.3

Cloned(Commentary)

Cloned (Comment)	Organism
gene pebB, in Synechococcus sp. WH8020, the genes encoding for pebA and pebB share an overlapping region. The pebA stop codon TGA is part of the pebB start codon ATG, recombinant expression of a translational fusion between pebA and pebB, N-terminally Strep-tagged and C-terminally His-tagged PebAgB, recombinant expression of GST-tagged or His-tagged PebB in Escherichia coli BL21(DE3)	Synechococcus sp. WH 8020

Protein Variants

Protein Variants	Comment	Organism
additional information	analysis wether addition of PebB to the immobilized PebA-DHBV complex will result in the interaction of PebA and PebB and, therefore, cause retention of PebB on the column. Retention of PebB on the immobilized PebA column is not observed, but a transfer of almost all PebA-bound DHBV to PebB is seen, DHBV is washed off the column with regular washing buffer. in Synechococcus sp. WH8020, the genes encoding for pebA and pebB share an overlapping region. The pebA stop codon TGA is part of the pebB start codon ATG. In order to generate a translational fusion between pebA and pebB, a guanine base is inserted into the start-stop region of the pebAB-operon generating an artificial fusion of both enzymes, termed PebAgB. The newly generated codon GTG encodes for a valine residue, which now serves as a diminutive linker between PebA and PebB. This fusion protein is significantly different to the phage encoded PebS (EC 1.3.7.6), which is a homologue to PebA. But the fusion protein PebAgB shows PebS-like activity. Comparison of the PebAgB-catalyzed conversion of BV with an assay containing both PebA and PebB reveals no significant changes in velocity	Synechococcus sp. WH 8020

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
thylakoid membrane	-	Synechococcus sp. WH 8020	42651	-

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Fe2+	in cofactor ferredoxin	Synechococcus sp. WH 8020

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
15,16-dihydrobiliverdin + reduced ferredoxin	Synechococcus sp. WH 8020	-	(3Z)-phycoerythrobilin + oxidized ferredoxin	-	?
additional information	Synechococcus sp. WH 8020	the enzyme performs substrate channeling with the 15,16-dihydrobiliverdin:ferredoxin oxidoreductase catalyzing the former catalytic step. Both enzymes transiently interact and that transfer of the intermediate is facilitated by a significantly higher binding affinity of DHBV toward phycoerythrobilin:ferredoxin oxidoreductase	?	-	-

Organism

Organism	UniProt	Comment	Textmining
Synechococcus sp. WH 8020	Q02190	-	-

Purification (Commentary)

Purification (Comment)	Organism
recombinant GST-tagged or His-tagged PebB from Escherichia coli BL21(DE3) by glutathione or nickel affinity chromatography, gel filtration, and ultrafiltration, recombinant tagged PebAgB by affinity chromatography	Synechococcus sp. WH 8020

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
15,16-dihydrobiliverdin + reduced ferredoxin	-	Synechococcus sp. WH 8020	(3Z)-phycoerythrobilin + oxidized ferredoxin	-	?
additional information	the enzyme performs substrate channeling with the 15,16-dihydrobiliverdin:ferredoxin oxidoreductase catalyzing the former catalytic step. Both enzymes transiently interact and that transfer of the intermediate is facilitated by a significantly higher binding affinity of DHBV toward phycoerythrobilin:ferredoxin oxidoreductase	Synechococcus sp. WH 8020	?	-	-
additional information	development of an on-column assay with substrate channeling for FDBRs, transient interaction of both PebA and PebB during the conversion of biliverdin IXa (BV) to phycoerythrobilin (PEB) via 15,16-dihydrobiliverdin (DHBV)	Synechococcus sp. WH 8020	?	-	-

Synonyms

Synonyms	Comment	Organism
PebB	-	Synechococcus sp. WH 8020

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
37	-	assay at	Synechococcus sp. WH 8020

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7.5	-	assay at	Synechococcus sp. WH 8020

Cofactor

Cofactor	Comment	Organism	Structure
Ferredoxin	-	Synechococcus sp. WH 8020

General Information

General Information	Comment	Organism
metabolism	during the biosynthesis of light-harvesting phycobilins in cyanobacteria, two members of the ferredoxin-dependent bilin reductases are involved in the reduction of the open-chain tetrapyrrole biliverdin IXa to the pink pigment phycoerythrobilin. The first reaction is catalyzed by 15,16-dihydrobiliverdin:ferredoxin oxidoreductase (PebA, EC 1.3.7.2) and produces the unstable intermediate 15,16-dihydrobiliverdin (DHBV). This intermediate is subsequently channeled to and converted by phycoerythrobilin:ferredoxin oxidoreductase to the final product phycoerythrobilin. An on-column assay employing immobilized enzyme in combination with UV-Vis and fluorescence spectroscopy reveals that both enzymes transiently interact and that transfer of the intermediate is facilitated by a significantly higher binding affinity of DHBV toward phycoerythrobilin:ferredoxin oxidoreductase (PebB). The intermediate DHBV is transferred via proximity channeling	Synechococcus sp. WH 8020
physiological function	phycobilisomes are composed of a core of allophycocyanin (APC) and radiating rods of phycocyanin (PC) and, depending on the species, phycoerythrin (PE) and phycoerythrocyanin (PEC), respectively. The individual phycobiliproteins are constituted of alpha- and beta-subunits building heterodimers and ultimately heterohexamers. Each subunit has between one and three covalently linked phycobilins bound. The two most abundant phycobilins in cyanobacteria are phycocyanobilin (PCB) and phycoerythrobilin (PEB) which are attached via conserved cysteine residues. During the biosynthesis of light-harvesting phycobilins in cyanobacteria, two members of the ferredoxin-dependent bilin reductases are involved in the reduction of the open-chain tetrapyrrole biliverdin IXa to the pink pigment phycoerythrobilin. The first reaction is catalyzed by 15,16-dihydrobiliverdin:ferredoxin oxidoreductase (PebA, UniProt ID Q02189) and produces the unstable intermediate 15,16-dihydrobiliverdin (DHBV). This intermediate is subsequently converted by phycoerythrobilin:ferredoxin oxidoreductase (PebB) to the final product phycoerythrobilin	Synechococcus sp. WH 8020

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Release 2023.1 (January 2023)