Database accession: MF7000853
Name: RbcX (Anabaena sp.)
PDB ID: 3hyb
Experimental method: X-ray (2.30 Å)
Assembly: Homodimer
Source organism: Anabaena sp
Primary publication of the structure:
Liu C, Young AL, Starling-Windhof A, Bracher A, Saschenbrecker S, Rao BV, Rao KV, Berninghausen O, Mielke T, Hartl FU, Beckmann R, Hayer-Hartl M
Coupled chaperone action in folding and assembly of hexadecameric Rubisco.
(2010) Nature 463: 197-202
PMID: 20075914
Abstract:
Form I Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase), a complex of eight large (RbcL) and eight small (RbcS) subunits, catalyses the fixation of atmospheric CO(2) in photosynthesis. The limited catalytic efficiency of Rubisco has sparked extensive efforts to re-engineer the enzyme with the goal of enhancing agricultural productivity. To facilitate such efforts we analysed the formation of cyanobacterial form I Rubisco by in vitro reconstitution and cryo-electron microscopy. We show that RbcL subunit folding by the GroEL/GroES chaperonin is tightly coupled with assembly mediated by the chaperone RbcX(2). RbcL monomers remain partially unstable and retain high affinity for GroEL until captured by RbcX(2). As revealed by the structure of a RbcL(8)-(RbcX(2))(8) assembly intermediate, RbcX(2) acts as a molecular staple in stabilizing the RbcL subunits as dimers and facilitates RbcL(8) core assembly. Finally, addition of RbcS results in RbcX(2) release and holoenzyme formation. Specific assembly chaperones may be required more generally in the formation of complex oligomeric structures when folding is closely coupled to assembly.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
protein folding chaperone protein folding chaperone
protein homodimerization activity protein homodimerization activity
Biological process:
carbon fixation carbon fixation
photosynthesis photosynthesis
ribulose bisphosphate carboxylase complex assembly ribulose bisphosphate carboxylase complex assembly
Cellular component:
carboxysome carboxysome
cytoplasm cytoplasm
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: RuBisCO chaperone RbcX
Source organism: Anabaena sp
Length: 135 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMNLKQIAKDTAKTLQSYLTYQALRTVLAQLGETNPPLALWLHNFSAGKVQDGEKYIEELFLEKPDLALRIMTVREHIAEEIAEFLPEMVVTGIQQANMEKRRQHLERMTQVSLSHPSPESEQQQFSDPDWDNLAS
UniProtKB AC: Q44212 (positions: 1-105)
Coverage: 77%
Name: RuBisCO chaperone RbcX
Source organism: Anabaena sp
Length: 135 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMNLKQIAKDTAKTLQSYLTYQALRTVLAQLGETNPPLALWLHNFSAGKVQDGEKYIEELFLEKPDLALRIMTVREHIAEEIAEFLPEMVVTGIQQANMEKRRQHLERMTQVSLSHPSPESEQQQFSDPDWDNLAS
UniProtKB AC: Q44212 (positions: 1-105)
Coverage: 77%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: Chaperonin-like RbcX
Evidence level: Indirect evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
There is no information on the stability/disoder of the monomeric forms. However, RbcX is a dimer in solution (PMID:17574029) and its biologically relevant form is the homodimer (a monomeric form with this fold is not known PMID:23295968, PMID:21821880). The structure is highly intertwined with the interface being extended and hydrophobic between the two four-helix-bundle cores and by the exchange of the C-terminal parts of the long a4 helices between the two subunits (PMID:21821880).
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
Download this entry's XML file (.xml)
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