Chaperonin Cofactors, Cpn10 and Cpn20, of Green Algae and Plants Function as Hetero-oligomeric Ring Complexes

Tsai, Yi-Chin Candace; Mueller‐Cajar, Oliver; Saschenbrecker, Sandra; Hartl, F. Ulrich; Hayer‐Hartl, Manajit

doi:10.1074/jbc.m112.365411

Cited by 50 publications

(88 citation statements)

References 60 publications

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“…The authors demonstrated that for the singlecelled alga Chlamydomonas (Chlamydomonas reinhardtii), the only functional co-chaperonin form was a mixed oligomer composed of a specific combination of Cpn10 and Cpn20 subtypes. The report showed that this phenomenon was not specific to algae, because Cpn10 and Cpn20 from Arabidopsis were also capable of forming mixed oligomers in vitro, in addition to the previously characterized homooligomers [29]. This finding offered a potential solution to the puzzle of how the homo-oligomeric eight-domained Cpn20, with fourfold symmetry, interacts with the heptameric ring of a Cpn60 oligomer.…”

Section: Box 1 Arabidopsis Chaperonin Familymentioning

confidence: 84%

“…Moreover, in spinach (Spinacia oleracea), specific antibodies to either the Cpn60a or the Cpn60b subunit type were able to coprecipitate both types together [15]. In vitro, Cpn60ab hetero-oligomers have been reconstituted from purified Cpn60a and Cpn60b monomers of pea (Pisum sativum) [19], and a recent study has shown that Arabidopsis (Arabidopsis thaliana) chaperonins expressed in and purified from E. coli form hetero-oligomers composed of seven Cpn60a and seven Cpn60b subunits [29].…”

Section: Composition Of Functional Chloroplast Chaperonin Oligomersmentioning

confidence: 97%

“…This implies that Cpn20 in this species must necessarily function as a homo-oligomer, and again this raises the symmetry dilemma. As an alternative solution, it has been proposed that the eighth Cpn10 domain of Cpn20 remains excluded and does not interact with Cpn60 [29]. Figure 1 depicts the multifarious nature of the chloroplast chaperonin system.…”

Section: Box 1 Arabidopsis Chaperonin Familymentioning

confidence: 97%

“…The second chloroplast co-chaperonin gene is unique to this organelle and consists of two Cpn10-like sequences joined head-to-tail [25]. The purified protein, with a subunit molecular weight of approximately 20 kDa (Cpn20), forms tetrameric, ring-like structures that are fully functional at refolding denatured proteins in vitro with GroEL and chloroplast Cpn60 [11,[25][26][27][28][29][30].…”

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confidence: 99%

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The complexity of chloroplast chaperonins

Gruber

Nisemblat

Azem

et al. 2013

Trends in Plant Science

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Section: Box 1 Arabidopsis Chaperonin Familymentioning

confidence: 84%

Section: Composition Of Functional Chloroplast Chaperonin Oligomersmentioning

confidence: 97%

Section: Box 1 Arabidopsis Chaperonin Familymentioning

confidence: 97%

mentioning

confidence: 99%

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The complexity of chloroplast chaperonins

Gruber

Nisemblat

Azem

et al. 2013

Trends in Plant Science

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“…The latter gene consists of two linked homologous cpn10 sequences. It is still not completely clear how these subunits oligomerize at the protein level [18], however, it has been reported that the cpn20 subunits may assemble into tetrameric species in vitro [19], or form hetero-oligomers with cpn10 subunits [20]. Until recently, the cpn20 protein was known to exist only in chloroplasts of algae and plants.…”

Section: Introductionmentioning

confidence: 99%

P. falciparum cpn20 Is a Bona Fide Co-Chaperonin That Can Replace GroES in E. coli

et al. 2013

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Human malaria is among the most ubiquitous and destructive tropical, parasitic diseases in the world today. The causative agent, Plasmodium falciparum, contains an unusual, essential organelle known as the apicoplast. Inhibition of this degenerate chloroplast results in second generation death of the parasite and is the mechanism by which antibiotics function in treating malaria. In order to better understand the biochemistry of this organelle, we have cloned a putative, 20 kDa, co-chaperonin protein, Pf-cpn20, which localizes to the apicoplast. Although this protein is homologous to the cpn20 that is found in plant chloroplasts, its ability to function as a co-chaperonin was questioned in the past. In the present study, we carried out a structural analysis of Pf-cpn20 using circular dichroism and analytical ultracentrifugation and then used two different approaches to investigate the ability of this protein to function as a co-chaperonin. In the first approach, we purified recombinant Pf-cpn20 and tested its ability to act as a co-chaperonin for GroEL in vitro, while in the second, we examined the ability of Pf-cpn20 to complement an E. coli depletion of the essential bacterial co-chaperonin GroES. Our results demonstrate that Pf-cpn20 is fully functional as a co-chaperonin in vitro. Moreover, the parasitic co-chaperonin is able to replace GroES in E. coli at both normal and heat-shock temperatures. Thus, Pf-cpn20 functions as a co-chaperonin in chaperonin-mediated protein folding. The ability of the malarial protein to function in E. coli suggests that this simple system can be used as a tool for further analyses of Pf-cpn20 and perhaps other chaperone proteins from P. falciparum.

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Red algal Rubisco fails to accumulate in transplastomic tobacco expressing Griffithsia monilis RbcL and RbcS genes

Lin

Hanson

2018

Plant Direct

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In C 3 plants, the carbon fixation step catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) represents a major rate-limiting step due to the competing oxygenation reaction, which leads to the energy-intensive photorespiration and lowers the overall photosynthetic efficiency. Hence, there is great biotechnological interest in replacing the Rubisco in C 3 crops with a more efficient enzyme. The Rubisco enzymes from red algae are among the most attractive choices due to their remarkable preference for carboxylation over oxygenation reaction. However, the biogenesis of Rubisco is extremely complex. The Rubisco enzymes in plants, algae, and cyanobacteria are made up of eight large and eight small subunits. The folding of the large subunits and the assembly of the large subunits with the small subunits to form a functional holoenzyme require specific chaperonin complexes and assembly factors. As a result, previous success in expressing foreign Rubisco in plants has been limited to Rubisco large subunits from closely related plant species and simpler bacterial enzymes. In our previous work, we successfully replaced the Rubisco in tobacco with a cyanobacterial enzyme, which was able to support the phototrophic growth of the transgenic plants. In this work, we used the same approach to express the Rubisco subunits from the red alga Griffithsia monilis in tobacco chloroplasts in the absence of the tobacco Rubisco large subunit.Although the red algal Rubisco genes are being transcribed in tobacco chloroplasts, the transgenic plants lack functional Rubisco and can only grow in a medium containing sucrose. Our results suggest that co-expression of compatible chaperones will be necessary for successful assembly of red algal Rubisco in plants. K E Y W O R D Schloroplast transformation, Griffithsia monilis, photosynthesis, Rubisco

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Chaperonin Cofactors, Cpn10 and Cpn20, of Green Algae and Plants Function as Hetero-oligomeric Ring Complexes

Cited by 50 publications

References 60 publications

The complexity of chloroplast chaperonins

The complexity of chloroplast chaperonins

P. falciparum cpn20 Is a Bona Fide Co-Chaperonin That Can Replace GroES in E. coli

Red algal Rubisco fails to accumulate in transplastomic tobacco expressing Griffithsia monilis RbcL and RbcS genes

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