Biosynthesis of phycobilins

Beale, Samuel I.

doi:10.1021/cr00018a008

Cited by 134 publications

(147 citation statements)

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“…Whereas the regioselectivity of the cleavage is the same in conversions of porphyrins into biliverdin, phytochromobilin, and phycobilins (Beale, 1993;Weller et al, 1996), the methine bridge carbon is lost in these cases. The same selectivity was also found in the red bilin from Chlorella protothecoides (Engel et al, 1991(Engel et al, , 1996, but another mechanism seems to be responsible for breakdown of Chl into the luciferin of the dinoflagellate Pyrocystis lunula, which is oxygenolytically cleaved at the C20/C1 mesoposition (Nakamura et al, 1989).…”

Section: Discussionmentioning

confidence: 98%

Chlorophyll Breakdown in Senescent Chloroplasts (Cleavage of Pheophorbide a in Two Enzymic Steps)

et al. 1997

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Section: Discussionmentioning

confidence: 98%

Chlorophyll Breakdown in Senescent Chloroplasts (Cleavage of Pheophorbide a in Two Enzymic Steps)

et al. 1997

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“…6 (step 1), we envisage that bilin reduction occurs by binding of reduced Fd to the PcyA-BV complex, followed by electron transfer to the bound bilin and proton transfer from a protein residue labeled D 1 -H to generate a neutral radical shown in step 2. The benzylic position would help to stabilize this radical by resonance within the extended tetrapyrrole -system, until a second electron and proton transfer, shown in steps 2 and 3, occurs to produce the intermediate 18 1 ,18 2 -DHBV IX␣. The hypothetical proton donors, D 1 -H and D 2 -H, could either be carboxylic acids (i.e.…”

Section: Pcya Prefers Plant Type [2fe-2s] Ferredoxins-pioneering Work Bymentioning

confidence: 99%

“…Phycocyanobilin (PCB) 1 is a linear tetrapyrrole (bilin) found in cyanobacteria, algae, and cryptomonads that functions as the direct precursor of the chromophores of the light-harvesting phycobiliproteins and cyanobacterial/algal phytochromes (1,2). The PCB biosynthetic pathway shares common intermediates with those of heme and chlorophyll to the level of protoporphyrin IX, whereupon the pathways diverge upon metalation with either iron or magnesium (1).…”

mentioning

confidence: 99%

“…The PCB biosynthetic pathway shares common intermediates with those of heme and chlorophyll to the level of protoporphyrin IX, whereupon the pathways diverge upon metalation with either iron or magnesium (1). All phycobilins share the common intermediacy of biliverdin IX␣ (BV IX␣), which is derived from heme (1,3). BV IX␣ is the product of heme oxygenase-mediated cleavage of the heme macrocycle, which yields equimolar quantities of BV IX␣, CO, and iron.…”

mentioning

confidence: 99%

“…1). Neither of the two likely dihydrobiliverdin (DHBV) intermediates, (3Z)-P⌽B or 18 1 ,18 2 -DHBV IX␣, have yet been detected (4). Since (3Z)-P⌽B is an intermediate in the biosynthesis of PCB, the precursor of the phytochrome chromophore in the green alga Mesotaenium caldariorum (5), its intermediacy in the PcyA-mediated biosynthesis of PCB in cyanobacteria is therefore a reasonable possibility.…”

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confidence: 99%

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Phycocyanobilin:Ferredoxin Oxidoreductase ofAnabaena sp. PCC 7120

Frankenberg

Lagarias

2003

Journal of Biological Chemistry

138

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In cyanobacteria, the biosynthesis of the phycobiliprotein and phytochrome chromophore precursor phycocyanobilin is catalyzed by the ferredoxin-dependent enzyme phycocyanobilin:ferredoxin oxidoreductase (PcyA), which mediates an atypical four-electron reduction of biliverdin IX␣. Here we describe the expression, affinity purification, and biochemical characterization of recombinant PcyA from Anabaena sp. PCC 7120. A monomeric protein with a native M r of 30,400 ؎ 5,000, recombinant PcyA forms a tight and stable stoichiometric complex with its substrate biliverdin IX␣. The enzyme exhibits a strong preference for plant type [2Fe-2S] ferredoxins; however, flavodoxin can also serve as an electron donor. HPLC analyses establish that catalysis proceeds via the two electron-reduced intermediate 18 1 ,18 2 -dihydrobiliverdin, indicating that exovinyl reduction precedes A-ring (endovinyl) reduction. Substrate specificity studies indicate that the arrangement of the A-and D-ring substituents alters the positioning of the bilin substrate within the enzyme, profoundly influencing the course of catalysis. Based on these observations and the apparent lack of a metal or small molecule cofactor, a radical mechanism for biliverdin IX␣ reduction by phycocyanobilin:ferredoxin oxidoreductase is envisaged.

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Monomeric and Dimeric Iron(III) Complexes of 5‐Hydroxy‐10,15,20‐triphenylporphyrin: Formation of Cyano and Pyridine Complexes of (5‐Oxo‐10,15,20‐triphenylphlorin)iron

Wojaczyński

Stępień

Latos‐Grażyński

2002

Euro J of Inorganic Chem

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The reaction of [(TrPP)FeII(py)2] (TrPP = dianion of 5,10,15‐triphenylporphyrin) with hydrogen peroxide results in oxygenation of the (porphyrin)iron and the formation of (10,15,20‐triphenyl‐5‐oxophlorin)iron [(5‐O‐TrPP)Fe(py)2]. Coupled oxidation of [(TrPP)FeIIICl] in the presence of ascorbic acid and potassium cyanide in methanol leads to oxidative hydroxylation of the porphyrin ring to form a cyclic dimer [(5‐O‐TrPP)FeIII]2. Three out of four pyrrole 1H NMR resonances of the dimeric complex present the characteristic displacement with respect to the typical position for the high‐spin (tetraphenylporphyrin)iron(III) complexes. The linewidths of the β‐H pyrrole resonances correlate with specific locations of the respective protons within the dimeric structure. Addition of HCl to [(5‐O‐TrPP)FeIII]2 results in cleavage of the dimer producing [(5‐OH‐TrPP)FeIIICl]. [(5‐O‐TrPP)FeIII]2 is also split with acetic anhydride to give (5‐acetoxy‐10,15,20‐triphenylporphyrin)iron(III). In the presence of [D5]pyridine or a large excess of cyanide ion, [(5‐O‐TrPP)FeIII]2 undergoes cleavage to form air‐sensitive [(5‐O‐TrPP)Fe(py)2] or [(5‐O‐TrPP)Fe(CN)2]2−. The pyrrole pattern observed for [(5‐O‐TrPP)Fe(py)2] is similar to that determined on the basis of an analysis carried out for four (oxophlorin)iron regioisomers obtained from hemes. For comparison, the characteristic 1H NMR features of the typical (5‐substituted‐10,15,20‐triphenylporphyrin)iron(III) complexes have been investigated for the series of high‐spin and low‐spin complexes. The spin‐density distribution in the (oxophlorin)iron skeleton is dominated by the radical‐like electronic structure. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Biosynthesis of phycobilins

Cited by 134 publications

References 49 publications

Chlorophyll Breakdown in Senescent Chloroplasts (Cleavage of Pheophorbide a in Two Enzymic Steps)

Chlorophyll Breakdown in Senescent Chloroplasts (Cleavage of Pheophorbide a in Two Enzymic Steps)

Phycocyanobilin:Ferredoxin Oxidoreductase ofAnabaena sp. PCC 7120

Monomeric and Dimeric Iron(III) Complexes of 5‐Hydroxy‐10,15,20‐triphenylporphyrin: Formation of Cyano and Pyridine Complexes of (5‐Oxo‐10,15,20‐triphenylphlorin)iron

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