6l1q

Crystal structure of AfCbbQ2, a MoxR AAA+-ATPase and CbbQO-type Rubisco activase from Acidithiobacillus ferrooxidans

spinqualitylabelsall models 6l1q, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6l1q is a 3 chain structure with sequence from Acidithiobacillus ferrooxidans ATCC 23270. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: ADP, PO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function B7J5E4_ACIF2 Publication Abstract from PubMed The vast majority of biological carbon dioxide fixation relies on the function of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). In most cases the enzyme exhibits a tendency to become inhibited by its substrate RuBP and other sugar phosphates. The inhibition is counteracted by diverse molecular chaperones known as Rubisco activases (Rcas). In some chemoautotrophic bacteria, the CbbQO-type Rca Q2O2 repairs inhibited active sites of hexameric form II Rubisco. The 2.2-A crystal structure of the MoxR AAA+ protein CbbQ2 from Acidithiobacillus ferrooxidans reveals the helix 2 insert (H2I) that is critical for Rca function and forms the axial pore of the CbbQ hexamer. Negative-stain electron microscopy shows that the essential CbbO adaptor protein binds to the conserved, concave side of the CbbQ2 hexamer. Site-directed mutagenesis supports a model in which adenosine 5'-triphosphate (ATP)-powered movements of the H2I are transmitted to CbbO via the concave residue L85. The basal ATPase activity of Q2O2 Rca is repressed but strongly stimulated by inhibited Rubisco. The characterization of multiple variants where this repression is released indicates that binding of inhibited Rubisco to the C-terminal CbbO VWA domain initiates a signal toward the CbbQ active site that is propagated via elements that include the CbbQ alpha4-beta4 loop, pore loop 1, and the presensor 1-beta hairpin (PS1-betaH). Detailed mechanistic insights into the enzyme repair chaperones of the highly diverse CO2 fixation machinery of Proteobacteria will facilitate their successful implementation in synthetic biology ventures. Insights into the mechanism and regulation of the CbbQO-type Rubisco activase, a MoxR AAA+ ATPase.,Tsai YC, Ye F, Liew L, Liu D, Bhushan S, Gao YG, Mueller-Cajar O Proc Natl Acad Sci U S A. 2019 Dec 17. pii: 1911123117. doi:, 10.1073/pnas.1911123117. PMID:31848241 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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