Structure of the RuBisCO chaperone RbcX from the thermophilic cyanobacterium<i>Thermosynechococcus elongatus</i>

Tarnawski, Mirosław; Krzywda, Szymon; Białek, Wojciech; Jaskólski, Mariusz; Szczepaniak, Andrzej

doi:10.1107/s1744309111018860

Cited by 9 publications

(6 citation statements)

References 32 publications

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“…of Cα positions of 0.267 to 0.577 Å). The subunits form arch-shaped, two-fold symmetric dimers with a hydrophobic cleft in the center ( Fig 4A ), similar to other known RbcX structures [ 12 , 17 , 18 ]. In each subunit helices α1-α4 form a four-helix bundle, which associates with helix α5 of the opposing subunit in the dimer ( Fig 4A ).…”

Section: Resultssupporting

confidence: 80%

Structural Analysis of the Rubisco-Assembly Chaperone RbcX-II from Chlamydomonas reinhardtii

et al. 2015

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The most prevalent form of the Rubisco enzyme is a complex of eight catalytic large subunits (RbcL) and eight regulatory small subunits (RbcS). Rubisco biogenesis depends on the assistance by specific molecular chaperones. The assembly chaperone RbcX stabilizes the RbcL subunits after folding by chaperonin and mediates their assembly to the RbcL8 core complex, from which RbcX is displaced by RbcS to form active holoenzyme. Two isoforms of RbcX are found in eukaryotes, RbcX-I, which is more closely related to cyanobacterial RbcX, and the more distant RbcX-II. The green algae Chlamydomonas reinhardtii contains only RbcX-II isoforms, CrRbcX-IIa and CrRbcX-IIb. Here we solved the crystal structure of CrRbcX-IIa and show that it forms an arc-shaped dimer with a central hydrophobic cleft for binding the C-terminal sequence of RbcL. Like other RbcX proteins, CrRbcX-IIa supports the assembly of cyanobacterial Rubisco in vitro, albeit with reduced activity relative to cyanobacterial RbcX-I. Structural analysis of a fusion protein of CrRbcX-IIa and the C-terminal peptide of RbcL suggests that the peptide binding mode of RbcX-II may differ from that of cyanobacterial RbcX. RbcX homologs appear to have adapted to their cognate Rubisco clients as a result of co-evolution.

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Section: Resultssupporting

confidence: 80%

Structural Analysis of the Rubisco-Assembly Chaperone RbcX-II from Chlamydomonas reinhardtii

et al. 2015

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“…The second most common application is to examine how normal modes might be used to describe the conformational changes that are observed or that might occur during substrate binding, product release, or catalytic activation [150,151,152,153,154,155,156,157,158,159,160,161,162,163]. This is probably one of the oldest uses of NMA and was applied at an early date to lysozyme [38,39,164].…”

Section: Applicationsmentioning

confidence: 99%

Normal Mode Analysis as a Routine Part of a Structural Investigation

2019

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Normal mode analysis (NMA) is a technique that can be used to describe the flexible states accessible to a protein about an equilibrium position. These states have been shown repeatedly to have functional significance. NMA is probably the least computationally expensive method for studying the dynamics of macromolecules, and advances in computer technology and algorithms for calculating normal modes over the last 20 years have made it nearly trivial for all but the largest systems. Despite this, it is still uncommon for NMA to be used as a component of the analysis of a structural study. In this review, we will describe NMA, outline its advantages and limitations, explain what can and cannot be learned from it, and address some criticisms and concerns that have been voiced about it. We will then review the most commonly used techniques for reducing the computational cost of this method and identify the web services making use of these methods. We will illustrate several of their possible uses with recent examples from the literature. We conclude by recommending that NMA become one of the standard tools employed in any structural study.

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“…Finally, replacement of RbcX by RbcS results in holoenzyme formation (Saschenbrecker et al, 2007 ; Liu et al, 2010 ). Highly homologous RbcX proteins exist in Thermosynechococcus elongates and Arabidopsis thaliana as revealed by their structures, implying this may be a conserved mechanism for Rubisco assembly across species (Tarnawski et al, 2011 ; Kolesinski et al, 2013 ).…”

Section: Chloroplast Chaperonin Assisted Rubisco Folding and Assemblymentioning

confidence: 99%

Chloroplast Chaperonin: An Intricate Protein Folding Machine for Photosynthesis

Zhao

Liu

2018

Front. Mol. Biosci.

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Group I chaperonins are large cylindrical-shaped nano-machines that function as a central hub in the protein quality control system in the bacterial cytosol, mitochondria and chloroplasts. In chloroplasts, proteins newly synthesized by chloroplast ribosomes, unfolded by diverse stresses, or translocated from the cytosol run the risk of aberrant folding and aggregation. The chloroplast chaperonin system assists these proteins in folding into their native states. A widely known protein folded by chloroplast chaperonin is the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), an enzyme responsible for the fixation of inorganic CO2 into organic carbohydrates during photosynthesis. Chloroplast chaperonin was initially identified as a Rubisco-binding protein. All photosynthetic eucaryotes genomes encode multiple chaperonin genes which can be divided into α and β subtypes. Unlike the homo-oligomeric chaperonins from bacteria and mitochondria, chloroplast chaperonins are more complex and exists as intricate hetero-oligomers containing both subtypes. The Group I chaperonin requires proper interaction with a detachable lid-like co-chaperonin in the presence of ATP and Mg2+ for substrate encapsulation and conformational transition. Besides the typical Cpn10-like co-chaperonin, a unique co-chaperonin consisting of two tandem Cpn10-like domains joined head-to-tail exists in chloroplasts. Since chloroplasts were proposed as sensors to various environmental stresses, this diversified chloroplast chaperonin system has the potential to adapt to complex conditions by accommodating specific substrates or through regulation at both the transcriptional and post-translational levels. In this review, we discuss recent progress on the unique structure and function of the chloroplast chaperonin system based on model organisms Chlamydomonas reinhardtii and Arabidopsis thaliana. Knowledge of the chloroplast chaperonin system may ultimately lead to successful reconstitution of eukaryotic Rubisco in vitro.

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Structure of the RuBisCO chaperone RbcX from the thermophilic cyanobacteriumThermosynechococcus elongatus

Cited by 9 publications

References 32 publications

Structural Analysis of the Rubisco-Assembly Chaperone RbcX-II from Chlamydomonas reinhardtii

Structural Analysis of the Rubisco-Assembly Chaperone RbcX-II from Chlamydomonas reinhardtii

Normal Mode Analysis as a Routine Part of a Structural Investigation

Chloroplast Chaperonin: An Intricate Protein Folding Machine for Photosynthesis

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