2v6a: Difference between revisions

Revision as of 19:53, 21 February 2008

CRYSTAL STRUCTURE OF CHLAMYDOMONAS REINHARDTII RUBISCO WITH LARGE-SUBUNIT MUTATIONS V331A, G344S

OverviewOverview

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.

About this StructureAbout this Structure

2V6A is a Protein complex structure of sequences from Chlamydomonas reinhardtii with , and as ligands. Active as Ribulose-bisphosphate carboxylase, with EC number 4.1.1.39 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

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., Karkehabadi S, Satagopan S, Taylor TC, Spreitzer RJ, Andersson I, Biochemistry. 2007 Oct 2;46(39):11080-9. Epub 2007 Sep 8. PMID:17824672

Page seeded by OCA on Thu Feb 21 18:53:28 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

@@ Line 4: / Line 4: @@
 ==Overview==
-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.
+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.
 ==About this Structure==
@@ Line 10: / Line 10: @@
 ==Reference==
-Structural Analysis of Altered Large-Subunit Loop-6/Carboxy-Terminus Interactions That Influence Catalytic Efficiency and CO(2)/O(2) Specificity of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase(,)., Karkehabadi S, Satagopan S, Taylor TC, Spreitzer RJ, Andersson I, Biochemistry. 2007 Oct 2;46(39):11080-9. Epub 2007 Sep 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17824672 17824672]
+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., Karkehabadi S, Satagopan S, Taylor TC, Spreitzer RJ, Andersson I, Biochemistry. 2007 Oct 2;46(39):11080-9. Epub 2007 Sep 8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17824672 17824672]
 [[Category: Chlamydomonas reinhardtii]]
 [[Category: Protein complex]]
@@ Line 17: / Line 17: @@
 [[Category: Karkehabadi, S.]]
 [[Category: Satagopan, S.]]
-[[Category: Spreitzer, R.J.]]
+[[Category: Spreitzer, R J.]]
-[[Category: Taylor, T.C.]]
+[[Category: Taylor, T C.]]
 [[Category: CAP]]
 [[Category: EDO]]
@@ Line 41: / Line 41: @@
 [[Category: transit peptide]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 10:50:04 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:53:28 2008''