Biosynthesis of chlorophylls from protoporphyrin IX

Willows, Robert D.

doi:10.1039/b110549n

Cited by 125 publications

(46 citation statements)

References 214 publications

(283 reference statements)

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“…VWA proteins have been well studied in eukaryotes, where they are involved in a range of processes, including cell adhesion, transport, the complement system, proteolysis, transcription, DNA repair, and ribosome biogenesis. Bacterial and archaeal VWA proteins are not as well characterized, although limited work has identified members involved in surface adhesion, serum opacity, fibrinogen binding, and metal insertion into protoporphyrin IX (21)(22)(23). Thus, to carry out their varied remodeling functions, many MoxR AAAϩ proteins probably work in conjunction with VWA domain-containing proteins.…”

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confidence: 99%

Formation of a Distinctive Complex between the Inducible Bacterial Lysine Decarboxylase and a Novel AAA+ ATPase

Snider

Gutsche

Lin

et al. 2006

Journal of Biological Chemistry

118

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confidence: 99%

Formation of a Distinctive Complex between the Inducible Bacterial Lysine Decarboxylase and a Novel AAA+ ATPase

Snider

Gutsche

Lin

et al. 2006

Journal of Biological Chemistry

118

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“…(B)Chl biosynthesis in green bacteria depends on approximately 10 enzymatic steps and begins with the insertion of magnesium into protoporphyrin IX (P IX ), the intermediate common to both the heme and (B)Chl biosynthetic pathways (10,11). Metal insertion is followed by methylation of the propionic acid group of ring C of MgP IX to form magnesium protoporphyrin IX monomethylester (MgP IX ME) (12)(13)(14)(15).…”

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confidence: 99%

Characterization of Three Homologs of the Large Subunit of the Magnesium Chelatase from Chlorobaculum tepidum and Interaction with the Magnesium Protoporphyrin IX Methyltransferase

Johnson

Schmidt‐Dannert

2008

Journal of Biological Chemistry

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Green bacteria synthesize several types of (bacterio)chlorophylls for the assembly of functional photosynthetic reaction centers and antenna complexes. A distinctive feature of green bacteria compared with other photosynthetic microbes is that their genomes contain multiple homologs of the large subunit (BchH) of the magnesium chelatase which is a three-subunit enzyme complex (BchH, BchD, and BchI) that inserts magnesium into protoporphyrin IX as the first committed step of (bacterio)chlorophyll biosynthesis. There is speculation that the additional BchH homologs may regulate the biosynthesis of each type of chlorophyll, although the biochemical properties of the different magnesium chelatase complexes from a single species of green bacteria have not yet been compared. In this study, we investigated the activities of all three chelatase complexes from the green sulfur bacterium Chlorobaculum tepidum and interactions with the next enzyme in the pathway, magnesium protoporphyrin IX methyltransferase (BchM). Although all three chelatase complexes insert magnesium into protoporphyrin IX, the activities range by a factor of 10 5 . Further, there are differences in the interactions between the BchH homologs and BchM; two of the subunits increase the methyltransferase activity by 30 -60%, and the third decreases it by 30%. Expression of the chelatase complexes alone and together with BchM in Escherichia coli overproducing protoporphyrin IX suggests that the chelatase is the rate-limiting enzyme. We observed that BchM uses protoporphyrin IX without bound metal as a substrate. Our results conflict with expectations generated by previous gene inactivation studies and suggest a complex regulation of chlorophyll biosynthesis in green bacteria.Chlorobaculum tepidum (formerly Chlorobium tepidum) is a green sulfur bacterium isolated from anoxygenic mats found near acidic high sulfide hot springs in New Zealand (1). Because it is naturally transformable and has a fully sequenced genome, C. tepidum has become a model system for understanding the physiology of green sulfur bacteria and specifically for understanding chlorophyll (Chl) 2 and bacteriochlorophyll biosynthesis (2-5).C. tepidum produces three types of Chls/Bcls: bacteriochlorophyll c, bacteriochlorophyll a, and Chl a. Bacteriochlorophyll c, the most abundant (B)Chl, is the primary pigment of the chlorosome, a light-harvesting antenna structure, whereas bacteriochlorophyll a and Chl a are the pigments involved in the primary electron transfer reactions in the photosynthetic reaction center complexes (3, 6, 7). Bacteriochlorophyll c is characterized by a C-3 1 hydroxyl group and the absence of the methoxycarbonyl of ring E. Both characteristics lead to selfassembling properties of bacteriochlorophyll c that extend the absorption properties of the supramolecular complex to longer wavelengths (8, 9).(B)Chl biosynthesis in green bacteria depends on approximately 10 enzymatic steps and begins with the insertion of magnesium into protoporphyrin IX (P IX ), the intermediate co...

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“…Reductions of ring D as well as of the vinyl group on ring B result in chlorophyllide a, which is converted to Chl a by an esterification of phytol. All of the intermediate products up to the step of chlorophyllide are common in the synthesis of all (bacterio-) chlorophylls (7,8). However, the enzymes carrying out most of the oxidation and reduction reactions are different in anaerobic and aerobic environments because they either are oxygen-sensitive or require different chemistry to catalyze the oxidations in the absence of oxygen (8,9).…”

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“…Metal-free protoporphyrin IX is formed after a number of decarboxylation and oxidation reactions. Protochlorophyllide is synthesized from protoporphyrin IX through magnesium insertion, methylation, and oxidative cyclization reactions forming a fifth ring (8). Reductions of ring D as well as of the vinyl group on ring B result in chlorophyllide a, which is converted to Chl a by an esterification of phytol.…”

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confidence: 99%

“…All of the intermediate products up to the step of chlorophyllide are common in the synthesis of all (bacterio-) chlorophylls (7,8). However, the enzymes carrying out most of the oxidation and reduction reactions are different in anaerobic and aerobic environments because they either are oxygen-sensitive or require different chemistry to catalyze the oxidations in the absence of oxygen (8,9). Genes homologous to the cyanobacterial genes encoding enzymes for each of the reaction steps up to Chl a are present in the genome of Acaryochloris (10).…”

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confidence: 99%

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18O Labeling of Chlorophyll d in Acaryochloris marina Reveals That Chlorophyll a and Molecular Oxygen Are Precursors

Schliep

Crossett

Willows

et al. 2010

Journal of Biological Chemistry

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Until recently, all oxygenic photosynthetic organisms had been found to contain chlorophyll (Chl) 3 a as their major photopigment (1). However, a novel cyanobacterium, Acaryochloris marina (Acaryochloris) that contains Chl d (Ͻ 95%) as its major photopigment (2), challenged the Chl a-centralized requirement in oxygenic photosynthesis. Chlorophyll d only differs from Chl a through one substitution at the C3 1 position: the vinyl group of Chl a is replaced by a formyl group in Chl d (Fig. 1). This substitution results in the following unique characteristics of Chl d: 1) its Q y absorption peaks (in vivo) lie between 690 and 740 nm (Fig. 1) where other oxygenic Chls (i.e.Chl a, b, or c) do not absorb (3) and 2) it is the only Chl found so far that can substitute for Chl a in charge separation in the reaction centers of oxygenic photosynthetic organisms (4 -6). However, the biosynthetic mechanism responsible for the formation of the C3 1 -formyl group of Chl d has not been determined.The known Chl biosynthetic pathway contains at least 17 enzymatic steps from the precursor ␦-aminolevulinic acid to Chl a. Eight molecules of ␦-aminolevulinic acid are condensed together to form four monopyrroles that condense to a linear tetrapyrrole, which in turn is cyclized to uropor-phyrinogen III (7). Metal-free protoporphyrin IX is formed after a number of decarboxylation and oxidation reactions. Protochlorophyllide is synthesized from protoporphyrin IX through magnesium insertion, methylation, and oxidative cyclization reactions forming a fifth ring (8). Reductions of ring D as well as of the vinyl group on ring B result in chlorophyllide a, which is converted to Chl a by an esterification of phytol. All of the intermediate products up to the step of chlorophyllide are common in the synthesis of all (bacterio-) chlorophylls (7,8). However, the enzymes carrying out most of the oxidation and reduction reactions are different in anaerobic and aerobic environments because they either are oxygen-sensitive or require different chemistry to catalyze the oxidations in the absence of oxygen (8,9). Genes homologous to the cyanobacterial genes encoding enzymes for each of the reaction steps up to Chl a are present in the genome of Acaryochloris (10).Radioisotopes and stable isotopes were widely applied in the elucidation of the biosynthetic pathway of Chls, the magnesium branch of tetrapyrrole biosynthesis (11-13). The oxygen atoms of Chl and BChl molecules have their origins in either molecular oxygen or water and thus are incorporated by an oxygenase or a hydratase reaction mechanism, respectively (9, 14). All four oxygen atoms of the C13 3 -and C17 3 -carboxyl groups arise from the precursor ␦-aminolevulinic acid and thus originate from water during ␦-aminolevulinic acid synthesis, which was confirmed by Porra et al. in 1995 and 1996 (15, 16). The fifth oxygen atom of the C13 1 -oxo group is derived from molecular oxygen in most aerobic photosynthetic organisms and is thus an oxygenase-type reaction (9,11,(15)(16)(17). Whereas this oxyg...

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Biosynthesis of chlorophylls from protoporphyrin IX

Cited by 125 publications

References 214 publications

Formation of a Distinctive Complex between the Inducible Bacterial Lysine Decarboxylase and a Novel AAA+ ATPase

Formation of a Distinctive Complex between the Inducible Bacterial Lysine Decarboxylase and a Novel AAA+ ATPase

Characterization of Three Homologs of the Large Subunit of the Magnesium Chelatase from Chlorobaculum tepidum and Interaction with the Magnesium Protoporphyrin IX Methyltransferase

18O Labeling of Chlorophyll d in Acaryochloris marina Reveals That Chlorophyll a and Molecular Oxygen Are Precursors

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