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Structure-function studies of ribulose-1,5-bisphosphate carboxylase/oxygenase: activation, thermostability, and CO2/O2 specificity

Karkehabadi, Saeid (2005). Structure-function studies of ribulose-1,5-bisphosphate carboxylase/oxygenase: activation, thermostability, and CO2/O2 specificity. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2005:28
ISBN 91-576-7027-7
[Doctoral thesis]

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Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase) catalyses the CO2 fixation of photosynthesis. Despite its central role for life, Rubisco is inefficient and is subject to competitive inhibition by O2. This makes Rubisco a target for mechanistic studies and engineering, requiring a detailed knowledge of the molecular basis for its catalysis and specificity. Rubisco from higher plants consists of eight large, and eight small subunits. This thesis investigates the role of structural elements of Rubisco, spanning from the active site on the large subunit to the small subunit and the subunit interfaces. The structure of Rubisco with a calcium ion in place of the native magnesium activator ion illustrates how the catalytic properties depend on the nature of the metal ion. The larger radius of the calcium ion and its reduced Lewis-acid character causes increases in certain metal-ligand distances, and could explain why calcium does not support catalysis. The mutation C172S in the active site was shown to simultaneously improve specificity and influence the redox-stability of Rubisco. Analysis of mutations (V331A, T342I) in a mobile loop (Loop 6) of the large subunit illustrates the importance of a precise geometry of the loop for catalytic efficiency and specificity. The substitution D473E at the C-terminus is shown to disrupt a network of hydrogen bonds relayed to Loop 6 and to cause disorder of the C-terminus. This may explain the reduced specificity of this mutant. Mutations at the interface of the large and small subunits also influence the stability and catalytic efficiency. Analysis of temperature factors in the structures of L290F and L290F/A222T pinpoints the regions of instability and suggests how the effect is reversed by one single mutation. The influence of interactions at the subunit interface on catalysis was analysed by replacement of the small-subunit βA-βB loop of Chlamydomonas Rubisco with the corresponding loops of Synechococcus (ABAN) and spinach (ABSO) Rubisco. The structures show a significant interaction area of the βA-βB loop in ABAN is lost, leading to reduced catalytic efficiency and specificity, whereas the total loop-interaction area in ABSO is similar to that in the spinach or wild-type enzymes.

Authors/Creators:Karkehabadi, Saeid
Title:Structure-function studies of ribulose-1,5-bisphosphate carboxylase/oxygenase: activation, thermostability, and CO2/O2 specificity
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2005
Number of Pages:44
ALLI. Karkehabadi, S., Taylor, T.C & Andersson, I. (2003). Calcium supports loop closure but not catalysis in Rubisco. J. Mol. Biol. 334, 65-73. II. Karkehabadi, S., Taylor, T.C., Spreitzer, R.J. & Andersson, I. (2005). Altered intersubunit interactions in crystal structures of catalytically compromised ribulosebisphosphate carboxylase/oxygenase. Biochemistry, 44, 113-120 III. Karkehabadi, S., Peddi, S.R., Anwaruzzaman, Md., Cederlund, A., Andersson, I. & Spreitzer, R.J. Chimeric Small Subunits Influence Catalysis Without Causing Global Conformational Changes in the Crystal Structure of Ribulose-1,5-Bisphosphate Carboxylase/OxygenaseManuscript. IV. Garcia, M. J., Karkehabadi, S., Spreitzer, R.J., Andersson, I. & Moreno, J. Structural and functional consequences of the substitution of vicinal residues Cys172 and Cys192 in the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase from Chlamydomonas reinhardtii. Manuscript. V. Karkehabadi, S., Taylor, T.C., Spreitzer, R.J. & Andersson, I. Structural analysis of altered large-subunit carboxy-terminus/loop-6 interactions that influence catalytic efficiency and CO2/O2 specificity of ribulose 1,5-bisphosphate carboxylase/oxygenase. Manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-7027-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X30 Life sciences
Subjects:Not in use, please see Agris categories
Agrovoc terms:rubisco, catalytic activity, chemical reactions, molecular biology, photosynthesis
Keywords:Rubisco, thermal stability, CO2/O2 specificity, site-directed mutagenesis, crystal structures, Chlamydomonas reinhardtii.
Permanent URL:
ID Code:792
Department:(NL, NJ) > Dept. of Molecular Biology (until 131231)
Deposited By: Saeid Karkehabadi
Deposited On:23 Mar 2005 00:00
Metadata Last Modified:02 Dec 2014 10:07

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