Thioredoxin Selectivity for Thiol-based Redox Regulation of Target Proteins in Chloroplasts

Yoshida, Keisuke; Hara, Satoshi; Hisabori, Toru

doi:10.1074/jbc.m115.647545

Cited by 95 publications

(121 citation statements)

References 53 publications

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“…FBPase, SBPase, and NADP-MDH were reduced by Trx-f1 and Trx-m2 with different efficiencies (Fig. 3C, lanes 2-4), in agreement with our previous report (24). By contrast, NTRC failed to reduce these proteins (Fig.…”

Section: Ntrc and Five Trx Subtypes Transfer Reducing Power To Targetsupporting

confidence: 82%

“…S8D). In accordance with our previous results (24,29), each protein showed distinct redox shift patterns upon illumination; in the wild-type plants, the ATP synthase CF 1 -γ subunit was fully reduced even under low-light conditions, whereas FBPase and SBPase were gradually reduced concomitantly with increasing light intensity. Redox states of the antioxidant enzymes PrxQ and 2-Cys Prx were essentially stably maintained irrespective of the light conditions.…”

Section: Ntr and Trx Domains Are Both Necessary For Ntrc-dependent Redoxsupporting

confidence: 75%

“…These values are comparable to the midpoint redox potential of Trx-z (-276 mV) and less negative than those of other Trxs (Fig. 4D) (24). The surface electrostatic potentials in the 3D protein structure model indicate that Trx-z has more negative surface charge than any other Trxs (27).…”

Section: Ntrc and Five Trx Subtypes Transfer Reducing Power To Targetsupporting

confidence: 55%

“…8). To simplify the model, we omitted depicting the functional diversity within the Trx family, which was clarified in part by previous studies (24,38,39). In this regard, we further found a previously undescribed Trx selectivity in redox regulation: Trx-y is the most efficient reducer of CHLI (Fig.…”

Section: Ntrc and Five Trx Subtypes Differentially Recognize Target Pmentioning

confidence: 84%

“…Therefore, systematic determination of Trx-z target proteins is an attractive research subject. Besides FLNs, several antioxidant enzymes are known to be the target of Trx-z so far (24,47), which is, however, unlikely to account for the trxz phenotype. In addition to the present finding of the NADPH/NTRC/Trx-z redox cascade, future identification of its downstream targets will further expand the chloroplast redox network beyond current expectations.…”

Section: Ntrc and Five Trx Subtypes Differentially Recognize Target Pmentioning

confidence: 99%

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Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability

Yoshida

Hisabori

2016

Proc. Natl. Acad. Sci. U.S.A.

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The thiol-based redox regulation system is believed to adjust chloroplast functions in response to changes in light environments. A redox cascade via the ferredoxin-thioredoxin reductase (FTR)/thioredoxin (Trx) pathway has been traditionally considered to serve as a transmitter of light signals to target enzymes. However, emerging data indicate that chloroplasts have a complex redox network composed of diverse redox-mediator proteins and target enzymes. Despite extensive research addressing this system, two fundamental questions are still unresolved: How are redox pathways orchestrated within chloroplasts, and why are chloroplasts endowed with a complicated redox network? In this report, we show that NADPH-Trx reductase C (NTRC) is a key redox-mediator protein responsible for regulatory functions distinct from those of the classically known FTR/Trx system. Target screening and subsequent biochemical assays indicated that NTRC and the Trx family differentially recognize their target proteins. In addition, we found that NTRC is an electron donor to Trx-z, which is a key regulator of gene expression in chloroplasts. We further demonstrate that cooperative control of chloroplast functions via the FTR/Trx and NTRC pathways is essential for plant viability. Arabidopsis double mutants impaired in FTR and NTRC expression displayed lethal phenotypes under autotrophic growth conditions. This severe growth phenotype was related to a drastic loss of photosynthetic performance. These combined results provide an expanded map of the chloroplast redox network and its biological functions.T o preserve the integrity and efficiency of photosynthesis and other metabolic reactions, chloroplast enzymes need to be flexibly and appropriately controlled in response to changes in light environments. The photosynthetic electron transport chain in the chloroplast thylakoid membrane converts light energy into chemical energy, which is captured and stored in ATP and NADPH. These molecules are primarily consumed by the Calvin-Benson cycle in the stroma, but part of the reducing power is used for other metabolic reactions in chloroplasts (e.g., nitrogen and sulfur metabolism). One pathway for the reducing power is the redox cascade, mediated by ferredoxin-thioredoxin reductase (FTR) and thioredoxin (Trx). In this system, FTR receives reducing power from the light-driven photosynthetic electron transport chain via ferredoxin and then donates the reducing power to Trx. A reduced form of Trx subsequently transfers reducing power to target proteins through a dithiol-disulfide exchange reaction, allowing the targets to modulate the enzymatic activities. The redox cascade via the FTR/Trx pathway provides the basis for thiol-based redox regulation in chloroplasts and ensures light-responsive control of chloroplast functions (1, 2).The FTR/Trx pathway has been considered the only pathway regulating redox reactions in chloroplasts. Information about its target proteins has also been limited to a specific set of lightactivated enzymes, such as some enzy...

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Section: Ntrc and Five Trx Subtypes Transfer Reducing Power To Targetsupporting

confidence: 82%

Section: Ntr and Trx Domains Are Both Necessary For Ntrc-dependent Redoxsupporting

confidence: 75%

Section: Ntrc and Five Trx Subtypes Transfer Reducing Power To Targetsupporting

confidence: 55%

Section: Ntrc and Five Trx Subtypes Differentially Recognize Target Pmentioning

confidence: 84%

Section: Ntrc and Five Trx Subtypes Differentially Recognize Target Pmentioning

confidence: 99%

See 3 more Smart Citations

Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability

Yoshida

Hisabori

2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

123

182

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Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA and RpaB response regulators

et al. 2022

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Cyanobacteria employ two‐component sensor‐response regulator systems to monitor and respond to environmental challenges. The response regulators RpaA, RpaB, Rre1 and RppA are integral to circadian clock function and abiotic stress acclimation in cyanobacteria. RpaA, RpaB and Rre1 are known to interact with ferredoxin or thioredoxin, raising the possibility of their thiol regulation. Here, we report that Synechocystis sp. PCC 6803 Rre1, RpaA and RpaB exist as higher‐order oligomers under oxidising conditions and that reduced thioredoxin A converts them to monomers. We further show that these response regulators contain redox‐responsive cysteine residues with an Em7 around −300 mV. These findings suggest a direct thiol modulation of the activity of these response regulators, independent of their cognate sensor kinases.

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Cysteine residues contribute to the regulation of Arabidopsis state transition 7 kinase

Ibrahim,

Lee,

Weaver

et al. 2024

FEBS Letters

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State transitions are an acclimatory response by which plants, algae, and cyanobacteria counteract photosynthetic inefficiency caused by changes in incident light quality. In plants and green algae, state transition 7 (STN7/STT7) kinase promotes state 2 transition. Conserved cysteine residues are implicated in STN7/STT7 regulation, but the precise nature of their involvement remains unclear. Here, an analysis of the STN7 thiols in vitro and a determination of their midpoint redox potential indicate that the lumenal disulfide linkage is unlikely to be redox regulated while the stromal cysteines form a regulatory intramolecular disulfide. We further show that thioredoxin f1 (Trx‐f1) reduces the STN7 stromal disulfide linkage as consistent with a Trx‐f1‐mediated inhibition of the kinase under high light.

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Thioredoxin Selectivity for Thiol-based Redox Regulation of Target Proteins in Chloroplasts

Cited by 95 publications

References 53 publications

Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability

Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability

Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA and RpaB response regulators

Cysteine residues contribute to the regulation of Arabidopsis state transition 7 kinase

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