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Title: Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance

Authors:
 [1];  [1];  [2];  [2];  [1]
  1. Biochemistry & Molecular Biology, Michigan State University, 612 Wilson Road, Rm 106 East Lansing MI 48824 USA, MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Road, Rm 106 East Lansing MI 48824 USA
  2. MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Road, Rm 106 East Lansing MI 48824 USA
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1400765
Grant/Contract Number:
FG02-91ER20021
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
The Plant Journal
Additional Journal Information:
Journal Volume: 87; Journal Issue: 6; Related Information: CHORUS Timestamp: 2017-10-20 15:28:05; Journal ID: ISSN 0960-7412
Publisher:
Wiley-Blackwell
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Carrillo, L. Ruby, Froehlich, John E., Cruz, Jeffrey A., Savage, Linda J., and Kramer, David M. Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance. United Kingdom: N. p., 2016. Web. doi:10.1111/tpj.13226.
Carrillo, L. Ruby, Froehlich, John E., Cruz, Jeffrey A., Savage, Linda J., & Kramer, David M. Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance. United Kingdom. doi:10.1111/tpj.13226.
Carrillo, L. Ruby, Froehlich, John E., Cruz, Jeffrey A., Savage, Linda J., and Kramer, David M. Sat . "Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance". United Kingdom. doi:10.1111/tpj.13226.
@article{osti_1400765,
title = {Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance},
author = {Carrillo, L. Ruby and Froehlich, John E. and Cruz, Jeffrey A. and Savage, Linda J. and Kramer, David M.},
abstractNote = {},
doi = {10.1111/tpj.13226},
journal = {The Plant Journal},
number = 6,
volume = 87,
place = {United Kingdom},
year = {Sat Aug 06 00:00:00 EDT 2016},
month = {Sat Aug 06 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1111/tpj.13226

Citation Metrics:
Cited by: 10works
Citation information provided by
Web of Science

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  • An NADPH thioredoxin reductase C was co-purified with a 2-Cys peroxiredoxin by the combination of anion exchange chromatography and electroelution from gel slices after native PAGE from a thermophilic cyanobacterium Thermosynechococcus elongatus as an NAD(P)H oxidase complex induced by oxidative stress. The result provided a strong evidence that the NADPH thioredoxin reductase C interacts with the 2-Cys peroxiredoxin in vivo. An in vitro reconstitution assay with purified recombinant proteins revealed that both proteins were essential for an NADPH-dependent reduction of H{sub 2}O{sub 2}. These results suggest that the reductase transfers the reducing power from NADPH to the peroxiredoxin, which reducesmore » peroxides in the cyanobacterium under oxidative stress. In contrast with other NADPH thioredoxin reductases, the NADPH thioredoxin reductase C contains a thioredoxin-like domain in addition to an NADPH thioredoxin reductase domain in the same polypeptide. Each domain contains a conserved CXYC motif. A point mutation at the CXYC motif in the NADPH thioredoxin reductase domain resulted in loss of the NADPH oxidation activity, while a mutation at the CXYC motif in the thioredoxin-like domain did not affect the electron transfer, indicating that this motif is not essential in the electron transport from NADPH to the 2-Cys peroxiredoxin.« less
  • Overexpression of AtNTRC (AtNTRC{sup OE}) in Arabidopsis thaliana led to a freezing and cold stress tolerance, whereas a knockout mutant (atntrc) showed a stress-sensitive phenotype. Biochemical analyses showed that the recombinant AtNTRC proteins exhibited a cryoprotective activity for malate dehydrogenase and lactic dehydrogenase. Furthermore, conclusive evidence of its interaction with nucleic acids in vitro is provided here on the basis of gel shift and electron microscopy analysis. Recombinant AtNTRC efficiently protected RNA and DNA from RNase A and metal catalyzed oxidation damage, respectively. The C-terminal thioredoxin domain is required for the nucleic acid–protein complex formation. From these results, it can bemore » hypothesized that AtNTRC, which is known to be an electron donor of peroxiredoxin, contributes the stability of macromolecules under cold stress. - Highlights: • AtNTRC has a cryoprotective activity in vitro. • Overexpression of AtNTRC increases tolerance to freezing and cold shock stresses. • Thioredoxin domain of AtNTRC protects nucleic acids in vitro. • AtNTRC inhibits protein aggregation under freezing stress in vitro.« less
  • In wild type plants, decreasing CO 2 lowers the activity of the chloroplast ATP synthase, slowing proton efflux from the thylakoid lumen resulting in buildup of thylakoid proton motive force (pmf). The resulting acidification of the lumen regulates both light harvesting, via the qE mechanism, and photosynthetic electron transfer through the cytochrome b 6f complex. Here in this paper, we show that the cfq mutant of Arabidopsis, harboring single point mutation in its γ-subunit of the chloroplast ATP synthase, increases the specific activity of the ATP synthase and disables its down-regulation under low CO 2. The increased thylakoid proton conductivitymore » (g H +) in cfq results in decreased pmf and lumen acidification, preventing full activation of qE and more rapid electron transfer through the b6f complex, particularly under low CO 2 and fluctuating light. These conditions favor the accumulation of electrons on the acceptor side of PSI, and result in severe loss of PSI activity. Comparing the current results with previous work on the pgr5 mutant suggests a general mechanism where increased PSI photodamage in both mutants is caused by loss of pmf, rather than inhibition of CEF per se. Overall, our results support a critical role for ATP synthase regulation in maintaining photosynthetic control of electron transfer to prevent photodamage.« less
  • The chloroplast ATP synthase catalyzes the light-driven synthesis of ATP and is activated in the light and inactivated in the dark by redox-modulation through the thioredoxin system. It has been proposed that this down-regulation is important for preventing wasteful hydrolysis of ATP in the dark. To test this proposal, we compared the effects of extended dark exposure in Arabidopsis lines expressing the wild-type and mutant forms of ATP synthase that are redox regulated or constitutively active. In contrast to the predictions of the model, we observed that plants with wild-type redox regulation lost photosynthetic capacity rapidly in darkness, whereas thosemore » expressing redox-insensitive form were far more stable. To explain these results, we propose that in wild-type plants, down-regulation of ATP synthase inhibits ATP hydrolysis, leading to dissipation of thylakoid proton motive force (pmf) and subsequent inhibition of protein transport across the thylakoid through the twin arginine transporter (Tat)-dependent and Secdependent import pathways, resulting in the selective loss of specific protein complexes. By contrast, in mutants with a redox-insensitive ATP synthase, pmf is maintained by ATP hydrolysis, thus allowing protein transport to maintain photosynthetic activities for extended periods in the dark. Hence, a basal level of Tat-dependent, as well as, Sec-dependent import activity, in the dark helps replenishes certain components of the photosynthetic complexes and thereby aids in maintaining overall complex activity. But, the influence of a dark pmf on thylakoid protein import, by itself, could not explain all the effects we observed in this study. For example, we also observed in wild type plants a large transient buildup of thylakoid pmf and nonphotochemical exciton quenching upon sudden illumination of dark adapted plants. Thus, we conclude that down-regulation of the ATP synthase is probably not related to preventing loss of ATP per se. Instead, ATP synthase redox regulation may be impacting a number of cellular processes such as (1) the accumulation of chloroplast proteins and/or ions or (2) the responses of photosynthesis to rapid changes in light intensity. A model highlighting the complex interplay between ATP synthase regulation and pmf in maintaining various chloroplast functions in the dark is presented.« less
  • Thioredoxin reductases (TrxRs) regulate the intracellular redox environment by using NADPH to provide reducing equivalents for thioredoxins (Trxs). Here we present the cloning and biochemical characterization of a putative TrxR (Ta0984) and a putative Trx (Ta0866) from Thermoplasma acidophilum. Our data identify Ta0866 as a Trx through its capacity to reduce insulin and be reduced by Escherichia coli TrxR in a NADPH-dependent manner. Our data also establish Ta0984 as a TrxR due to its ability to reduce T. acidophilum Trx (taTrx), although not in a NADPH- or NADH-dependent manner. To explore the apparent inability of taTrxR to use NADPH ormore » NADH as a reductant, we carried out a complete electrochemical characterization, which suggests that redox potential is not the source of this nonreactivity [Hamill et al. (2008) Biochemistry 47, 9738-9746]. Turning to crystallographic analysis, a 2.35 {angstrom} resolution structure of taTrxR, also presented here, shows that despite the overall structural similarity to the well-characterized TrxR from E. coli (RMSD 1.30 {angstrom}{sup 2} for chain A), the 'NADPH binding pocket' is not conserved. E. coli TrxR residues implicated in NADPH binding, H175, R176, R177, and R181, have been substituted with E185, Y186, M187, and M191 in the ta protein. Thus, we have identified a Trx and TrxR protein system from T. acidophilum for which the TrxR shares overall structural and redox properties with other TrxRs but lacks the appropriate binding motif to use the standard NADPH reductant. Our discovery of a TrxR that does not use NADPH provides a new twist in redox regulation.« less