Structural insight into the cooperation of chloroplast chaperonin subunits

Zhang, Shijia; Zhou, Huan; Yu, Feng; Bai, Chen; Zhao, Qian; He, Jianhua; Liu, Cuimin

doi:10.1186/s12915-016-0251-8

Cited by 20 publications

(23 citation statements)

References 62 publications

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“…The major protein folding system in plant chloroplasts consists of Group I chaperonin GroEL (Cpn60), which forms 14 subunit double-ring complexes that require functional association with GroES (Cpn10/20) oligomers Zhang et al, 2016). Chloroplast chaperonin is composed of different Cpn60a and Cpn60b isoforms that form the oligomeric cage that binds to unfolded substrates (Tr€ osch et al, 2015).…”

Section: Further Studies Into the Complementarity Of Groel With Rubismentioning

confidence: 99%

Engineering chloroplasts to improve Rubisco catalysis: prospects for translating improvements into food and fiber crops

2016

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494I.495II.496III.496IV.499V.499VI.501VII.501VIII.502IX.505X.506507References507 Summary The uncertainty of future climate change is placing pressure on cropping systems to continue to provide stable increases in productive yields. To mitigate future climates and the increasing threats against global food security, new solutions to manipulate photosynthesis are required. This review explores the current efforts available to improve carbon assimilation within plant chloroplasts by engineering Rubisco, which catalyzes the rate‐limiting step of CO2 fixation. Fixation of CO2 and subsequent cycling of 3‐phosphoglycerate through the Calvin cycle provides the necessary carbohydrate building blocks for maintaining plant growth and yield, but has to compete with Rubisco oxygenation, which results in photorespiration that is energetically wasteful for plants. Engineering improvements in Rubisco is a complex challenge and requires an understanding of chloroplast gene regulatory pathways, and the intricate nature of Rubisco catalysis and biogenesis, to transplant more efficient forms of Rubisco into crops. In recent times, major advances in Rubisco engineering have been achieved through improvement of our knowledge of Rubisco synthesis and assembly, and identifying amino acid catalytic switches in the L‐subunit responsible for improvements in catalysis. Improving the capacity of CO2 fixation in crops such as rice will require further advances in chloroplast bioengineering and Rubisco biogenesis.

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Section: Further Studies Into the Complementarity Of Groel With Rubismentioning

confidence: 99%

Engineering chloroplasts to improve Rubisco catalysis: prospects for translating improvements into food and fiber crops

2016

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“…As seven is the smallest number required to form one ring, it is impossible that the chaperonin consists of a homo-oligomeric CPN60a ring. Moreover, we have shown that CPN60b1 oligomers are not fully functional and that there is cooperation between Cpn60a and Cpn60b during its allosteric movement (Zhang et al, 2016a). The two rings need to be hetero-oligomeric to ensure that both rings are fully functional.…”

Section: Discussionmentioning

confidence: 99%

“…A structure of the human homo-oligomeric mitochondrial chaperonin has also been determined by X-ray crystallography and revealed a symmetrical football shape (Nisemblat et al, 2015). Recently, we have reported the crystal structure of the homo-oligomeric CPN60b1 chloroplast chaperonin from Chlamydomonas, which shares a similar topology with GroEL (Zhang et al, 2016a). The structure of the authentic heterooligomeric chloroplast chaperonin is still elusive, however, even after many years of effort, presumably because of the labile nature of the recombinant hetero-oligomeric complex.…”

Section: Discussionmentioning

confidence: 99%

“…We previously reported the crystal structure of the Chlamydomonas CPN60b1 homo-oligomer, which shares a similar structural topology with group-I chaperonins (Zhang et al, 2016a). Compared with homo-oligomeric GroEL and Hsp60, however, the hetero-oligomeric chloroplast chaperonin system suggests an asymmetric structural organization that might be related to its unique function.…”

Section: The Stoichiometry Of Cpn60 Subunits In Native Cpn60ab1b2 Commentioning

confidence: 99%

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Hetero‐oligomeric CPN60 resembles highly symmetric group‐I chaperonin structure revealed by Cryo‐EM

et al. 2019

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Summary The chloroplast chaperonin system is indispensable for the biogenesis of Rubisco, the key enzyme in photosynthesis. Using Chlamydomonas reinhardtii as a model system, we found that in vivo the chloroplast chaperonin consists of CPN60α, CPN60β1 and CPN60β2 and the co‐chaperonin of the three subunits CPN20, CPN11 and CPN23. In Escherichia coli, CPN20 homo‐oligomers and all possible other chloroplast co‐chaperonin hetero‐oligomers are functional, but only that consisting of CPN11/20/23‐CPN60αβ1β2 can fully replace GroES/GroEL under stringent stress conditions. Endogenous CPN60 was purified and its stoichiometry was determined to be 6:2:6 for CPN60α:CPN60β1:CPN60β2. The cryo‐EM structures of endogenous CPN60αβ1β2/ADP and CPN60αβ1β2/co‐chaperonin/ADP were solved at resolutions of 4.06 and 3.82 Å, respectively. In both hetero‐oligomeric complexes the chaperonin subunits within each ring are highly symmetric. Through hetero‐oligomerization, the chloroplast co‐chaperonin CPN11/20/23 forms seven GroES‐like domains, which symmetrically interact with CPN60αβ1β2. Our structure also reveals an uneven distribution of roof‐forming domains in the dome‐shaped CPN11/20/23 co‐chaperonin and potentially diversified surface properties in the folding cavity of the CPN60αβ1β2 chaperonin that might enable the chloroplast chaperonin system to assist in the folding of specific substrates.

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“…We previously reported the crystal structure of the Chlamydomonas CPN60β1 homo-oligomer, which shares a similar structural topology with group I chaperonins (Zhang et al, 2016a). However, compared to the homo-oligomeric GroEL and Hsp60, the hetero-oligomeric chloroplast chaperonin system suggests an asymmetric structural organization which might be related to its unique function.…”

Section: Cryo-em Structure Of Ecpn60αβ1β2 and Ecpn60αβ1β2-cpn11/20/23mentioning

confidence: 99%

Hetero-oligomeric CPN60 resembles highly symmetric group I chaperonin structure revealed by Cryo-EM

Liu

Zhao

Zhang³

et al. 2018

Preprint

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The chloroplast chaperonin system is indispensable for the biogenesis of Rubisco, the key enzyme in photosynthesis. Using Chlamydomonas reinhardtii as the model system, we revealed that chloroplast chaperonin is consisted of CPN60α, CPN60β1, and CPN60β2, and co-chaperonin is composed of three subunits CPN20, CPN11 and CPN23 in vivo. CPN20 homo-oligomers and all possible other chloroplast co-chaperonin hetero-oligomers are functional, but only CPN11/20/23-CPN60αβ1β2 pair can fully replace GroES/GroEL in E. coli at stringent growth condition. Endogenous CPN60 was purified and its stoichiometry was determined to be 6:2:6 for CPN60α:CPN60β1:CPN60β2. The cryo-EM structures of endogenous CPN60αβ1β2/ADP and CPN60αβ1β2/co-chaperonin/ADP were solved at resolutions of 4.06 Å and 3.82Å, respectively. In both hetero-oligomeric complexes the chaperonin subunits within each ring are highly symmetric. The chloroplast co-chaperonin CPN11/20/23 formed seven GroES-like domains through hetero-oligomerization which symmetrically interact with CPN60αβ1β2. Our structures also reveal an uneven distribution of roof-like structures in the dome-shaped CPN11/20/23 and potentially diversified surface properties in the folding cavity of CPN60αβ1β2 that might enable the chloroplast chaperonin system to assist in the folding of specific substrates.

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Structural insight into the cooperation of chloroplast chaperonin subunits

Cited by 20 publications

References 62 publications

Engineering chloroplasts to improve Rubisco catalysis: prospects for translating improvements into food and fiber crops

Engineering chloroplasts to improve Rubisco catalysis: prospects for translating improvements into food and fiber crops

Hetero‐oligomeric CPN60 resembles highly symmetric group‐I chaperonin structure revealed by Cryo‐EM

Hetero-oligomeric CPN60 resembles highly symmetric group I chaperonin structure revealed by Cryo-EM

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