Biology:Protochlorophyllide reductase

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The reduction of ring D of protochlorophyllide completes the biosynthesis of chlorophyllide a
light-dependent protochlorophyllide reductase
Identifiers
EC number1.3.1.33
CAS number68518-04-7
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BRENDABRENDA entry
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MetaCycmetabolic pathway
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PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
light-independent protochlorophyllide reductase
Dpor.png
Crystallographic structure of heterooctamer of a dark-operative protochlorophyllide oxidoreductase from Prochlorococcus marinus.[1]
Identifiers
EC number1.3.7.7
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum

In enzymology, protochlorophyllide reductases (POR)[2][3] are enzymes that catalyze the conversion from protochlorophyllide to chlorophyllide a. They are oxidoreductases participating in the biosynthetic pathway to chlorophylls.[4][5]

There are two structurally unrelated proteins with this sort of activity, referred to as light-dependent (LPOR) and dark-operative (DPOR). The light- and NADPH-dependent reductase is part of the short-chain dehydrogenase/reductase (SDR) superfamily and is found in plants and oxygenic photosynthetic bacteria,[6][7] while the ATP-dependent dark-operative version is a completely different protein, consisting of three subunits that exhibit significant sequence and quaternary structure similarity to the three subunits of nitrogenase.[8] This enzyme may be evolutionary older; due to its bound iron-sulfur clusters is highly sensitive to free oxygen and does not function if the atmospheric oxygen concentration exceeds about 3%.[9] It is possible that evolutionary pressure associated with the great oxidation event resulted in the development of the light-dependent system.

The light-dependent version (EC 1.3.1.33) uses NADPH:

protochlorophyllide + NADPH + H+ [math]\displaystyle{ \rightleftharpoons }[/math] chlorophyllide a + NADP+

While the light-independent or dark-operative version (EC 1.3.7.7) uses ATP and ferredoxin:[10][11][12]

protochlorophyllide a + reduced ferredoxin + 2 ATP + 2 H2O = chlorophyllide a + oxidized ferredoxin + 2 ADP + 2 phosphate

Light-dependent

The light-dependent version has the accepted name protochlorophyllide reductase. The systematic name is chlorophyllide-a :NADP+ 7,8-oxidoreductase. Other names in common use include NADPH2-protochlorophyllide oxidoreductase, NADPH-protochlorophyllide oxidoreductase, NADPH-protochlorophyllide reductase, protochlorophyllide oxidoreductase, and protochlorophyllide photooxidoreductase.

LPOR is one of only three known light-dependent enzymes. The enzyme enables light-dependent protochlorophyllide reduction via direct local hydride transfer from NADPH and a longer-range proton transfer along a defined structural pathway.[13] LPOR is a ~40kDa monomeric enzyme, for which the structure has been solved by X-ray crystallography. It is part of the SDR superfamily, which includes alcohol dehydrogenase, and consists of a Rossman-fold NADPH-binding site and a substrate-specific C-terminal segment region. The protochlorophyllide substrate is thought to bind to a cavity near the nicotinamide end of the bound NADPH.[7][13] LPOR is primarily found in plants and oxygenic photosynthetic bacteria, as well as in some algae.

Light-independent

The light-independent version has the accepted name of ferredoxin:protochlorophyllide reductase (ATP-dependent). Systematically it is known as ATP-dependent ferredoxin:protochlorophyllide-a 7,8-oxidoreductase. Other names in common use include light-independent protochlorophyllide reductase and dark-operative protochlorophyllide reductase (DPOR).

DPOR is a nitrogenase homologue[8] and adopts an almost identical overall architecture arrangement to both nitrogenase as well as the downstream chlorophyllide a reductase (COR). The enzyme consists of a catalytic heterotetramer and two transiently-bound ATPase dimers (right).[14] Similar to nitrogenase, the reduction mechanism relies on an electron transfer from the iron-sulfur cluster of the ATPase domain, through a secondary cluster on the catalytic heterotetramer and finally to the protochlorophyllide-bound active site (which, distinct from nitrogenase, does not contain FeMoco). The reduction requires significantly less input than the nitrogenase reaction, requiring only a 2-electron reduction and 4 ATP equivalents, and as such may require an auto-inhibitory mechanism to avoid over-activity.[15]

DPOR can alternatively take as its substrate the compound with a second vinyl group (instead of an ethyl group) in the structure, in which case the reaction is

3,8-divinylprotochlorophyllide + reduced ferredoxin + 2 ATP + 2 H2O [math]\displaystyle{ \rightleftharpoons }[/math] 3,8-divinylchlorophyllide a + oxidized ferredoxin + 2 ADP + 2 phosphate

This enzyme is present in photosynthetic bacteria, cyanobacteria, green algae and gymnosperms.[4][16]

See also

References

  1. ↑ PDB: 2ynm​; "Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex.". Proc Natl Acad Sci U S A 110 (6): 2094–2098. 2013. doi:10.1073/pnas.1218303110. PMID 23341615. Bibcode: 2013PNAS..110.2094M. 
  2. ↑ Griffiths WT (1978). "Reconstitution of chlorophyllide formation by isolated etioplast membranes". Biochem. J. 174 (3): 681–92. doi:10.1042/bj1740681. PMID 31865. 
  3. ↑ "The protochlorophyllide holochrome of barley (Hordeum vulgare L.) Isolation and characterization of the NADPH:protochlorophyllide oxidoreductase". Eur. J. Biochem. 111 (1): 251–8. 1980. doi:10.1111/j.1432-1033.1980.tb06100.x. PMID 7439188. 
  4. ↑ 4.0 4.1 Willows, Robert D. (2003). "Biosynthesis of chlorophylls from protoporphyrin IX". Natural Product Reports 20 (6): 327–341. doi:10.1039/B110549N. PMID 12828371. 
  5. ↑ Bollivar, David W. (2007). "Recent advances in chlorophyll biosynthesis". Photosynthesis Research 90 (2): 173–194. doi:10.1007/s11120-006-9076-6. PMID 17370354. 
  6. ↑ Nomata, Jiro; Kondo, Toru; Mizoguchi, Tadashi; Tamiaki, Hitoshi; Itoh, Shigeru; Fujita, Yuichi (May 2015). "Dark-operative protochlorophyllide oxidoreductase generates substrate radicals by an iron-sulphur cluster in bacteriochlorophyll biosynthesis" (in en). Scientific Reports 4 (1): 5455. doi:10.1038/srep05455. ISSN 2045-2322. PMID 24965831. 
  7. ↑ 7.0 7.1 Dong, Chen-Song; Zhang, Wei-Lun; Wang, Qiao; Li, Yu-Shuai; Wang, Xiao; Zhang, Min; Liu, Lin (2020-04-14). "Crystal structures of cyanobacterial light-dependent protochlorophyllide oxidoreductase" (in en). Proceedings of the National Academy of Sciences 117 (15): 8455–8461. doi:10.1073/pnas.1920244117. ISSN 0027-8424. PMID 32234783. 
  8. ↑ 8.0 8.1 Yuichi Fujita and Carl E. Bauer (2000). Reconstitution of Light-independent Protochlorophyllide Reductase from Purified Bchl and BchN-BchB Subunits. J. Biol. Chem., Vol. 275, Issue 31, 23583-23588. [1]
  9. ↑ S.Yamazaki, J.Nomata, Y.Fujita (2006) Differential operation of dual protochlorophyllide reductases for chlorophyll biosynthesis in response to environmental oxygen levels in the cyanobacterium Leptolyngbya boryana. Plant Physiology, 2006, 142, 911-922 [2]
  10. ↑ "Identification of a nifDK-like gene (ORF467) involved in the biosynthesis of chlorophyll in the cyanobacterium Plectonema boryanum". Plant & Cell Physiology 34 (2): 305–14. March 1993. PMID 8199775. 
  11. ↑ "NB-protein (BchN-BchB) of dark-operative protochlorophyllide reductase is the catalytic component containing oxygen-tolerant Fe-S clusters". FEBS Letters 582 (9): 1346–50. April 2008. doi:10.1016/j.febslet.2008.03.018. PMID 18358835. 
  12. ↑ "X-ray crystal structure of the light-independent protochlorophyllide reductase". Nature 465 (7294): 110–4. May 2010. doi:10.1038/nature08950. PMID 20400946. Bibcode: 2010Natur.465..110M. 
  13. ↑ 13.0 13.1 Zhang, Shaowei; Heyes, Derren J.; Feng, Lingling; Sun, Wenli; Johannissen, Linus O.; Liu, Huanting; Levy, Colin W.; Li, Xuemei et al. (2019-10-31). "Structural basis for enzymatic photocatalysis in chlorophyll biosynthesis" (in en). Nature 574 (7780): 722–725. doi:10.1038/s41586-019-1685-2. ISSN 0028-0836. PMID 31645759. Bibcode: 2019Natur.574..722Z. http://www.nature.com/articles/s41586-019-1685-2. 
  14. ↑ Moser, Jürgen; Lange, Christiane; Krausze, Joern; Rebelein, Johannes; Schubert, Wolf-Dieter; Ribbe, Markus W.; Heinz, Dirk W.; Jahn, Dieter (2013-02-05). "Structure of ADP-aluminium fluoride-stabilized protochlorophyllide oxidoreductase complex" (in en). Proceedings of the National Academy of Sciences 110 (6): 2094–2098. doi:10.1073/pnas.1218303110. ISSN 0027-8424. PMID 23341615. Bibcode: 2013PNAS..110.2094M. 
  15. ↑ Corless, Elliot I.; Saad Imran, Syed Muhammad; Watkins, Maxwell B.; Bacik, John-Paul; Mattice, Jenna R.; Patterson, Angela; Danyal, Karamatullah; Soffe, Mark et al. (January 2021). "The flexible N-terminus of BchL autoinhibits activity through interaction with its [4Fe-4S cluster and released upon ATP binding"] (in en). Journal of Biological Chemistry 296: 100107. doi:10.1074/jbc.RA120.016278. PMID 33219127. 
  16. ↑ "Recent advances in chlorophyll biosynthesis". Photosynthesis Research 90 (2): 173–94. November 2006. doi:10.1007/s11120-006-9076-6. PMID 17370354. 

Ferredoxin:protochlorophyllide+reductase+(ATP-dependent) at the US National Library of Medicine Medical Subject Headings (MeSH)



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