2V6A

Crystal structure of Chlamydomonas reinhardtii Rubisco with large- subunit mutations V331A, G344S

Summary for 2V6A

• Entry DOI: 10.2210/pdb2v6a/pdb
• Related: 1GK8 1IR2 1UW9 1UWA 1UZD 1UZH 2V63 2V67 2V68 2V69
• Descriptor: RIBULOSE BISPHOSPHATE CARBOXYLASE LARGE CHAIN, RIBULOSE BISPHOSPHATE CARBOXYLASE SMALL CHAIN 1, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: large subunit loop 6 mutation, co2/o2 specificity, carbon dioxide fixation, photosynthesis, transit peptide, photorespiration, metal-binding, hydroxylation, oxidoreductase, methylation, chloroplast, calvin cycle, monooxygenase, lyase, rubisco, plastid, magnesium, acetylation
• Biological source: CHLAMYDOMONAS REINHARDTII; More
• Cellular location: Plastid, chloroplast: P00877 P00873
• Total number of polymer chains: 16
• Total formula weight: 558566.35

Authors

Karkehabadi, S.,Satagopan, S.,Taylor, T.C.,Spreitzer, R.J.,Andersson, I. (deposition date: 2007-07-14, release date: 2007-07-31, Last modification date: 2023-12-13)

Primary citation

Karkehabadi, S.,Satagopan, S.,Taylor, T.C.,Spreitzer, R.J.,Andersson, I.
Structural Analysis of Altered Large-Subunit Loop-6-Carboxy-Terminus Interactions that Influence Catalytic Efficiency and Co2-O2 Specificity of Ribulose-1,5-Bisphosphate Carboxylase Oxygenase
Biochemistry, 46:11080-, 2007

PubMed Abstract: The loop between alpha-helix 6 and beta-strand 6 in the alpha/beta-barrel of ribulose-1,5-bisphosphate carboxylase/oxygenase plays a key role in discriminating between CO2 and O2. Genetic screening in Chlamydomonas reinhardtii previously identified a loop-6 V331A substitution that decreases carboxylation and CO2/O2 specificity. Revertant selection identified T342I and G344S substitutions that restore photosynthetic growth by increasing carboxylation and specificity of the V331A enzyme. In numerous X-ray crystal structures, loop 6 is closed or open depending on the activation state of the enzyme and the presence or absence of ligands. The carboxy terminus folds over loop 6 in the closed state. To study the molecular basis for catalysis, directed mutagenesis and chloroplast transformation were used to create T342I and G344S substitutions alone. X-ray crystal structures were then solved for the V331A, V331A/T342I, T342I, and V331A/G344S enzymes, as well as for a D473E enzyme created to assess the role of the carboxy terminus in loop-6 closure. V331A disturbs a hydrophobic pocket, abolishing several van der Waals interactions. These changes are complemented by T342I and G344S, both of which alone cause decreases in CO2/O2 specificity. In the V331A/T342I revertant enzyme, Arg339 main-chain atoms are displaced. In V331A/G344S, alpha-helix 6 is shifted. D473E causes disorder of the carboxy terminus, but loop 6 remains closed. Interactions between a transition-state analogue and several residues are altered in the mutant enzymes. However, active-site Lys334 at the apex of loop 6 has a normal conformation. A variety of subtle interactions must be responsible for catalytic efficiency and CO2/O2 specificity.

PubMed: 17824672
DOI: 10.1021/BI701063F

Experimental method

X-RAY DIFFRACTION (1.5 Å)