3ZUH

Negative stain EM Map of the AAA protein CbbX, a red-type Rubisco activase from R. sphaeroides

Summary for 3ZUH

• Entry DOI: 10.2210/pdb3zuh/pdb
• Related: 3SYK 3SYL
• EMDB information: 1932
• Descriptor: PROTEIN CBBX, RIBULOSE-1,5-DIPHOSPHATE, ADENOSINE-5'-DIPHOSPHATE (3 entities in total)
• Functional Keywords: atp binding protein, aaa+ protein
• Biological source: RHODOBACTER SPHAEROIDES
• Total number of polymer chains: 6
• Total formula weight: 200101.52

Authors

Mueller-Cajar, O.,Stotz, M.,Wendler, P.,Hartl, F.U.,Bracher, A.,Hayer-Hartl, M. (deposition date: 2011-07-19, release date: 2011-11-09, Last modification date: 2024-05-08)

Primary citation

Mueller-Cajar, O.,Stotz, M.,Wendler, P.,Hartl, F.U.,Bracher, A.,Hayer-Hartl, M.
Structure and Function of the Aaa+ Protein Cbbx, a Red-Type Rubisco Activase.
Nature, 479:194-, 2011

PubMed Abstract: Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the fixation of atmospheric CO(2) in photosynthesis, but tends to form inactive complexes with its substrate ribulose 1,5-bisphosphate (RuBP). In plants, Rubisco is reactivated by the AAA(+) (ATPases associated with various cellular activities) protein Rubisco activase (Rca), but no such protein is known for the Rubisco of red algae. Here we identify the protein CbbX as an activase of red-type Rubisco. The 3.0-Å crystal structure of unassembled CbbX from Rhodobacter sphaeroides revealed an AAA(+) protein architecture. Electron microscopy and biochemical analysis showed that ATP and RuBP must bind to convert CbbX into functionally active, hexameric rings. The CbbX ATPase is strongly stimulated by RuBP and Rubisco. Mutational analysis suggests that CbbX functions by transiently pulling the carboxy-terminal peptide of the Rubisco large subunit into the hexamer pore, resulting in the release of the inhibitory RuBP. Understanding Rubisco activation may facilitate efforts to improve CO(2) uptake and biomass production by photosynthetic organisms.

PubMed: 22048315
DOI: 10.1038/NATURE10568

Experimental method

ELECTRON MICROSCOPY (21 Å)