2PEN

Crystal structure of RbcX, crystal form I

Summary for 2PEN

• Entry DOI: 10.2210/pdb2pen/pdb
• Related: 2PEI 2PEJ 2PEK 2PEM 2PEO 2PEQ
• Descriptor: ORF134 (2 entities in total)
• Functional Keywords: helix bundle, protein complex assembly, chaperone
• Biological source: Synechococcus sp.
• Total number of polymer chains: 6
• Total formula weight: 91704.50

Authors

Saschenbrecker, S.,Bracher, A.,Vasudeva Rao, K.,Vasudeva Rao, B.,Hartl, F.U.,Hayer-Hartl, M. (deposition date: 2007-04-03, release date: 2007-07-10, Last modification date: 2024-02-21)

Primary citation

Saschenbrecker, S.,Bracher, A.,Rao, K.V.,Rao, B.V.,Hartl, F.U.,Hayer-Hartl, M.
Structure and Function of RbcX, an Assembly Chaperone for Hexadecameric Rubisco.
Cell(Cambridge,Mass.), 129:1189-1200, 2007

PubMed Abstract: After folding, many proteins must assemble into oligomeric complexes to become biologically active. Here we describe the role of RbcX as an assembly chaperone of ribulose-bisphosphate carboxylase/oxygenase (Rubisco), the enzyme responsible for the fixation of atmospheric carbon dioxide. In cyanobacteria and plants, Rubisco is an approximately 520 kDa complex composed of eight large subunits (RbcL) and eight small subunits (RbcS). We found that cyanobacterial RbcX functions downstream of chaperonin-mediated RbcL folding in promoting the formation of RbcL(8) core complexes. Structural analysis revealed that the 15 kDa RbcX forms a homodimer with two cooperating RbcL-binding regions. A central cleft specifically binds the exposed C-terminal peptide of RbcL subunits, enabling a peripheral surface of RbcX to mediate RbcL(8) assembly. Due to the dynamic nature of these interactions, RbcX is readily displaced from RbcL(8) complexes by RbcS, producing the active enzyme. The strategies employed by RbcX in achieving substrate specificity and efficient product release may be generally relevant in assisted assembly reactions.

PubMed: 17574029
DOI: 10.1016/j.cell.2007.04.025

Experimental method

X-RAY DIFFRACTION (2.8 Å)