Protochlorophyllide reductase explained
light-dependent protochlorophyllide reductase |
Ec Number: | 1.3.1.33 |
Cas Number: | 68518-04-7 |
Go Code: | 0016630 |
light-independent protochlorophyllide reductase |
Ec Number: | 1.3.7.7 |
In enzymology, protochlorophyllide reductases (POR)[1] [2] are enzymes that catalyze the conversion from protochlorophyllide to chlorophyllide a. They are oxidoreductases participating in the biosynthetic pathway to chlorophylls.[3] [4]
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,[5] [6] 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.[7] 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%.[8] 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 uses NADPH:
protochlorophyllide + NADPH + H+
chlorophyllide
a +
NADP+While the light-independent or dark-operative version uses ATP and ferredoxin:[9] [10] [11]
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.[12] 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. 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 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).[13] 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.[14]
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
3,8-divinylchlorophyllide
a + oxidized ferredoxin + 2 ADP + 2 phosphate
This enzyme is present in photosynthetic bacteria, cyanobacteria, green algae and gymnosperms.[15]
See also
Notes and References
- Griffiths WT . 1978 . Reconstitution of chlorophyllide formation by isolated etioplast membranes . Biochem. J. . 174 . 681 - 92 . 31865 . 3 . 10.1042/bj1740681 . 1185970 .
- 10.1111/j.1432-1033.1980.tb06100.x . Apel K, Santel HJ, Redlinger TE, Falk H . 1980 . The protochlorophyllide holochrome of barley (Hordeum vulgare L.) Isolation and characterization of the NADPH:protochlorophyllide oxidoreductase . Eur. J. Biochem. . 111 . 251 - 8 . 7439188 . 1 . free .
- Biosynthesis of chlorophylls from protoporphyrin IX . Willows . Robert D. . Natural Product Reports . 2003 . 20 . 6 . 327–341 . 10.1039/B110549N . 12828371.
- 10.1007/s11120-006-9076-6 . Recent advances in chlorophyll biosynthesis . 2007 . Bollivar . David W. . Photosynthesis Research . 90 . 2 . 173–194 . 17370354 . 23808539 .
- 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 . Scientific Reports . en . 4 . 1 . 5455 . 10.1038/srep05455 . 2045-2322 . 4071322 . 24965831.
- 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 . Proceedings of the National Academy of Sciences . en . 117 . 15 . 8455–8461 . 10.1073/pnas.1920244117 . 0027-8424 . 7165480 . 32234783. free .
- 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. https://www.jbc.org/article/S0021-9258(19)66014-X/fulltext
- 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 http://cat.inist.fr/?aModele=afficheN&cpsidt=18274807
- Fujita Y, Matsumoto H, Takahashi Y, Matsubara H . 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 . 8199775 .
- Nomata J, Ogawa T, Kitashima M, Inoue K, Fujita Y . 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 . 18358835 . 10.1016/j.febslet.2008.03.018 . free .
- Muraki N, Nomata J, Ebata K, Mizoguchi T, Shiba T, Tamiaki H, Kurisu G, Fujita Y . 6 . X-ray crystal structure of the light-independent protochlorophyllide reductase . Nature . 465 . 7294 . 110–4 . May 2010 . 20400946 . 10.1038/nature08950 . 2010Natur.465..110M . 4427639 .
- Zhang . Shaowei . Heyes . Derren J. . Feng . Lingling . Sun . Wenli . Johannissen . Linus O. . Liu . Huanting . Levy . Colin W. . Li . Xuemei . Yang . Ji . Yu . Xiaolan . Lin . Min . 2019-10-31 . Structural basis for enzymatic photocatalysis in chlorophyll biosynthesis . Nature . en . 574 . 7780 . 722–725 . 10.1038/s41586-019-1685-2 . 31645759 . 2019Natur.574..722Z . 204849396 . 0028-0836.
- 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 . Proceedings of the National Academy of Sciences . en . 110 . 6 . 2094–2098 . 10.1073/pnas.1218303110 . 0027-8424 . 3568340 . 23341615. 2013PNAS..110.2094M . free .
- Corless . Elliot I. . Saad Imran . Syed Muhammad . Watkins . Maxwell B. . Bacik . John-Paul . Mattice . Jenna R. . Patterson . Angela . Danyal . Karamatullah . Soffe . Mark . Kitelinger . Robert . Seefeldt . Lance C. . Origanti . Sofia . January 2021 . The flexible N-terminus of BchL autoinhibits activity through interaction with its [4Fe-4S] cluster and released upon ATP binding . Journal of Biological Chemistry . en . 296 . 100107 . 10.1074/jbc.RA120.016278 . 7948495 . 33219127. free .
- Bollivar DW . Recent advances in chlorophyll biosynthesis . Photosynthesis Research . 90 . 2 . 173–94 . November 2006 . 17370354 . 10.1007/s11120-006-9076-6 . 23808539 .