Mechanisms of Chloroplast Protein Import in Plants

Jarvis, Paul; Kessler, Félix

doi:10.1007/978-1-4939-1136-3_9

Cited by 4 publications

(3 citation statements)

References 232 publications

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“…These proteins are imported into the chloroplast in an unfolded state. 53 Following cleavage of the signal peptide by stromal signal peptidase, molecular chaperones in the stroma assist their folding to the functional state. In the stroma, folding of newly synthesized RbcL subunits by the Cpn60αβ/Cpn20 chaperonin is followed by assembly to RbcL dimers and higher oligomers mediated by Raf1 and RbcX acting in cooperation or in parallel.…”

Section: ■ Insights From Recombinant Expression Of Plant Rubiscomentioning

confidence: 99%

“…The RbcL subunit is chloroplast-encoded and synthesized on ribosomes in the chloroplast stroma, while most chloroplast proteins in plants, including the folding and assembly factors, as well as RbcS, are nuclear-encoded and are synthesized on cytosolic ribosomes with a chloroplast targeting sequence (red). These proteins are imported into the chloroplast in an unfolded state 53. Following cleavage of the signal peptide by stromal signal peptidase, molecular chaperones in the stroma assist their folding to the functional state.…”

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Complex Chaperone Dependence of Rubisco Biogenesis

Wilson

Hayer‐Hartl

2018

Biochemistry

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Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), a ∼530 kDa complex of 8 large (RbcL) and 8 small subunits (RbcS), mediates the fixation of atmospheric CO into usable sugars during photosynthesis. Despite its fundamental role, Rubisco is a remarkably inefficient enzyme and thus is produced by plants in huge amounts. It has long been a key target for bioengineering with the goal to increase crop yields. However, such efforts have been hampered by the complex requirement of Rubisco biogenesis for molecular chaperones. Recent studies have identified an array of auxiliary factors needed for the folding and assembly of the Rubisco subunits. The folding of plant RbcL subunits is mediated by the cylindrical chloroplast chaperonin, Cpn60, and its cofactor Cpn20. Folded RbcL requires a number of additional Rubisco specific assembly chaperones, including RbcX, Rubisco accumulation factors 1 (Raf1) and 2 (Raf2), and the Bundle sheath defective-2 (BSD2), to mediate the assembly of the RbcL intermediate complex. Incorporation of the RbcS and displacement of the assembly factors generates the active holoenzyme. An Escherichia coli strain expressing the chloroplast chaperonin and auxiliary factors now allows the expression of functional plant Rubisco, paving the way for Rubisco engineering by large scale mutagenesis. Here, we review our current understanding on how these chaperones cooperate to produce one of the most important enzymes in nature.

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Section: ■ Insights From Recombinant Expression Of Plant Rubiscomentioning

confidence: 99%

mentioning

confidence: 99%

Complex Chaperone Dependence of Rubisco Biogenesis

Wilson

Hayer‐Hartl

2018

Biochemistry

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“…The Rubisco large subunit, RbcL, is encoded and synthesized in the chloroplast. The small subunit, RbcS, as well as the chaperones are encoded in the nucleus, synthesized on the ribosomes in the cytosol, and transported into the chloroplasts via a Tic/Toc translocation complex (Jarvis and Kessler, 2014). RAF1 and/or RbcX help synthesize the RbcL 2 dimer and will be replaced by BSD2 for a RbcL 8 BSD2 8 .…”

Section: Rubisco Chaperonesmentioning

confidence: 99%

Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C₃ photosynthesis: Prospects on modern crop improvement

Jin

Chen

Yang

et al. 2022

Plant Cell & Environment

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Photosynthesis is a process that uses solar energy to fix CO2 in the air and converts it into sugar, and ultimately powers almost all life activities on the earth. C3 photosynthesis is the most common form of photosynthesis in crops. Current efforts of increasing crop yields in response to growing global food requirement are mostly focused on improving C3 photosynthesis. In this review, we summarized the strategies of C3 photosynthesis improvement in terms of Rubisco properties and photorespiratory limitation. Potential engineered targets include Rubisco subunits and their catalytic sites, Rubisco assembly chaperones, and Rubisco activase. In addition, we reviewed multiple photorespiratory bypasses built by strategies of synthetic biology to reduce the release of CO2 and ammonia and minimize energy consumption by photorespiration. The potential strategies are suggested to enhance C3 photosynthesis and boost crop production.

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Orchestral manoeuvres in the light: crosstalk needed for regulation of the Chlamydomonas carbon concentration mechanism

Santhanagopalan

Wong

Mathur

et al. 2021

Journal of Experimental Botany

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The inducible carbon concentration mechanism (CCM) in Chlamydomonas reinhardtii has been well defined from a molecular and ultrastructural perspective. Inorganic carbon transport proteins, and strategically located carbonic anhydrases deliver CO2 within the chloroplast pyrenoid matrix where Rubisco is packaged. However, there is little understanding of the fundamental signalling and sensing processes leading to CCM induction. While external CO2 limitation has been believed to be the primary cue, the coupling between energetic supply and inorganic carbon demand through regulatory feedback from light harvesting and photorespiration signals could provide the original CCM trigger. Key questions regarding the integration of these processes are addressed in this review. We consider how the chloroplast functions as a crucible for photosynthesis, importing and integrating nuclear-encoded components from the cytoplasm, and sending retrograde signals to the nucleus to regulate CCM induction. We hypothesize that induction of the CCM is associated with retrograde signals associated with photorespiration and/or light stress. We have also examined the significance of common evolutionary pressures for origins of two co-regulated processes, namely the CCM and photorespiration, in addition to identifying genes of interest involved in transcription, protein folding, and regulatory processes which are needed to fully understand the processes leading to CCM induction.

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Mechanisms of Chloroplast Protein Import in Plants

Cited by 4 publications

References 232 publications

Complex Chaperone Dependence of Rubisco Biogenesis

Complex Chaperone Dependence of Rubisco Biogenesis

Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C₃ photosynthesis: Prospects on modern crop improvement

Orchestral manoeuvres in the light: crosstalk needed for regulation of the Chlamydomonas carbon concentration mechanism

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Mechanisms of Chloroplast Protein Import in Plants

Cited by 4 publications

References 232 publications

Complex Chaperone Dependence of Rubisco Biogenesis

Complex Chaperone Dependence of Rubisco Biogenesis

Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C3 photosynthesis: Prospects on modern crop improvement

Orchestral manoeuvres in the light: crosstalk needed for regulation of the Chlamydomonas carbon concentration mechanism

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Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C₃ photosynthesis: Prospects on modern crop improvement