MetaCyc Enzyme: ribulose bisphosphate carboxylase

Species: Synechocystis sp. PCC 6803

Subunit composition of ribulose bisphosphate carboxylase = [CbbS]8[(CbbL)2]4
         Cbbl dimer = (CbbL)2 (summary available)

General Background

There are four types of enzymes in the ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) superfamily.

All higher plants, cyanobacteria and most eukaryotic algae possess type I enzymes, hexadecamers of eight large and eight small subunits (see ribulose bisphosphate carboxylase from Synechocystis sp. PCC 6803 for an example).

Type II enzymes are generally found as dimers of large subunits, and are found in some photosynthetic proteobacteria, chemoautotrophic bacteria and some dinoflagellate algae (see ribulose bisphosphate carboxylase from Rhodospirillum rubrum for an example). Both types I and type II enzymes catalyze the capture of CO2 into an organic carbon form as part of the Calvin-Benson-Bassham (CBB) cycle.

Type III enzymes are found in Archaea, and are capable of carbon fixation, even though these organisms do not have a CBB cycle. They are dimeric (see ribulose bisphosphate carboxylase from Thermococcus kodakarensis for an example).

Type IV enzymes are missing some crucial residues, and are not able to catalyze carbon fixation. They are also dimeric, and have been shown to participate in methionine salvage (see 2,3-diketo-5-methylthiopentyl-1-phosphate enolase from Bacillus subtilis and 5-methylthioribulose-1-phosphate isomerase from Rhodospirillum rubrum for examples).

About This Enzyme

ribulose bisphosphate carboxylase from Synechocystis sp. PCC 6803 catalyzes the first reaction in the Calvin-Benson-Bassham cycle (CBB cycle). It consists of two types of subunits, known as CbbL and CbbS. In the Rubisco large subunit, as in other proteins containing an αβ barrel, the active site is found on one side of the barrel at the carboxy end of the β-strands. Residues from the N-terminal domain of one subunit and the C-terminal domain from the second subunit build up one active site, so a large subunit dimer is required. In the type I enzymes the large subunits form dimers, and the active RubisCO complex consists of four such dimers in a "head-to-tail" conformation, linked by disulfide links, and eight small subunits.

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Revised 09-Nov-2006 by Caspi R , SRI International

Enzymatic reaction of: ribulose bisphosphate carboxylase

Synonyms: RuBisCO, ribulose bisphosphate carboxylase/oxygenase, 3-phospho-D-glycerate carboxy-lyase (dimerizing)

EC Number:

2 3-phospho-D-glycerate + 2 H+ <=> D-ribulose-1,5-bisphosphate + CO2 + H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

EC Number:

2-phosphoglycolate + 3-phospho-D-glycerate + 2 H+ <=> D-ribulose-1,5-bisphosphate + oxygen

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

In Pathways: ethylene biosynthesis V (engineered) , photosynthetic 3-hydroxybutyrate biosynthesis (engineered) , oxygenic photosynthesis , Calvin-Benson-Bassham cycle

The carboxylation of ribulose 1,5-bisphosphate by CO2 is the primary event in the photosynthetic fixation of CO2. RuBisCO can also catalyze the oxygenolysis of ribulose 1,5-bisphosphate yielding phosphoglycerate and phosphoglycolate. The photorespiratory and photosynthetic reactions occur simultaneously and in competition at the same active site [Bowien].

Activators (Allosteric): Mg2+

Subunit of ribulose bisphosphate carboxylase: CbbS

Synonyms: RbcS, CbbS

Gene: cbbS Accession Number: G-527 (MetaCyc)

Molecular Weight: 13.239 kD (from nucleotide sequence)

Unification Links: Protein Model Portal:P54206 , SMR:P54206 , String:1148.slr0012 , UniProt:P54206

Relationship Links: InterPro:IN-FAMILY:IPR000894 , Pfam:IN-FAMILY:PF00101 , Smart:IN-FAMILY:SM00961

Subunit of ribulose bisphosphate carboxylase: Cbbl dimer

Synonyms: rbcL

Gene: cbbL Accession Number: G-526 (MetaCyc)

Subunit composition of Cbbl dimer = [CbbL]2

Molecular Weight of Polypeptide: 52.491 kD (from nucleotide sequence)

Unification Links: Pride:P54205 , Protein Model Portal:P54205 , SMR:P54205 , String:1148.slr0009 , UniProt:P54205

Relationship Links: InterPro:IN-FAMILY:IPR000685 , InterPro:IN-FAMILY:IPR017443 , InterPro:IN-FAMILY:IPR017444 , InterPro:IN-FAMILY:IPR020878 , InterPro:IN-FAMILY:IPR020888 , Pfam:IN-FAMILY:PF00016 , Pfam:IN-FAMILY:PF02788 , Prosite:IN-FAMILY:PS00157

Two large subunits of RubisCO form a dimer.

Gene Citations: [Amichay93]


Amichay93: Amichay D, Levitz R, Gurevitz M (1993). "Construction of a Synechocystis PCC6803 mutant suitable for the study of variant hexadecameric ribulose bisphosphate carboxylase/oxygenase enzymes." Plant Mol Biol 23(3);465-76. PMID: 8219082

Bowien: Bowien B, editor, Schlegel HG, editor "Autotrophic Bacteria." Science Tech Publishers Madison, WI.

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Sun Mar 29, 2015, biocyc13.