Crystal Structure and Biochemical Characterization of Chlamydomonas FDX2 Reveal Two Residues that, When Mutated, Partially Confer FDX2 the Redox Potential and Catalytic Properties of FDX1
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
The green alga Chlamydomonas reinhardtii contains six plastidic [2Fe2S]-cluster ferredoxins (FDXs), with FDX1 as the predominant isoform under photoautotrophic growth. FDX2 is highly similar to FDX1 and has been shown to interact with specific enzymes (such as nitrite reductase), as well as to share interactors with FDX1, such as the hydrogenases (HYDA), ferredoxin:NAD(P) reductase I (FNR1), and pyruvate:ferredoxin oxidoreductase (PFR1), albeit performing at low catalytic rates. Here we report the FDX2 crystal structure solved at 1.18 Å resolution. Based on differences between the Chlorella fusca FDX1 and C. reinhardtii FDX2 structures, we generated and purified point-mutated versions of the FDX2 protein and assayed them in vitro for their ability to catalyze hydrogen and NADPH photo-production. The data show that structural differences at two amino acid positions contribute to functional differences between FDX1 and FDX2, suggesting that FDX2 might have evolved from FDX1 toward a different physiological role in the cell. Moreover, we demonstrate that the mutations affect both the midpoint potentials of the FDX and kinetics of the FNR reaction, possibly due to altered binding between FDX and FNR. An effect on H2 photo-production rates was also observed, although the kinetics of the reaction were not further characterized.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1242885
- Report Number(s):
- NREL/JA-2700-62499
- Journal Information:
- Photosynthesis Research, Vol. 128, Issue 1; Related Information: Photosynthesis Research; ISSN 0166-8595
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Evolution of Chlamydomonas reinhardtii ferredoxins and their interactions with [FeFe]-hydrogenases
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journal | June 2017 |
Characterization of photosynthetic ferredoxin from the Antarctic alga Chlamydomonas sp. UWO241 reveals novel features of cold adaptation
|
journal | May 2018 |
Association of Ferredoxin:NADP+ oxidoreductase with the photosynthetic apparatus modulates electron transfer in Chlamydomonas reinhardtii
|
journal | June 2017 |
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