Biomaterial Database

Chloroplast intragenic suppression enhances the low CO2/O2 specificity of mutant ribulose-bisphosphate carboxylase/oxygenase. 1989

Z X Chen, and R J Spreitzer

Department of Biochemistry, University of Nebraska, Lincoln 68583-0718.

The competition between CO2 and O2 at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase limits net CO2 fixation in photosynthesis. In the green alga Chlamydomonas reinhardtii, a mutation in the chloroplast large-subunit gene reduces the CO2/O2 specificity of the enzyme by 37% and causes valine-331 to be replaced by alanine. Revertant selection identified an intragenic suppressor mutation that increases the CO2/O2 specificity of the mutant enzyme by 33%. This second-site mutation causes threonine-342 to be replaced by isoleucine. The complementing amino acid substitutions flank a catalytically essential lysyl residue at position 334. It thus appears that a number of amino acid residues can influence the CO2/O2 specificity of this bifunctional enzyme. The well defined chloroplast genetics of C. reinhardtii allows the interactions of these residues to be investigated.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D002696	Chlamydomonas	A genus GREEN ALGAE in the order VOLVOCIDA. It consists of solitary biflagellated organisms common in fresh water and damp soil.	Chlamydomona
D002736	Chloroplasts	Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.	Chloroplast,Etioplasts,Etioplast
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D012273	Ribulose-Bisphosphate Carboxylase	A carboxy-lyase that plays a key role in photosynthetic carbon assimilation in the CALVIN-BENSON CYCLE by catalyzing the formation of 3-phosphoglycerate from ribulose 1,5-biphosphate and CARBON DIOXIDE. It can also utilize OXYGEN as a substrate to catalyze the synthesis of 2-phosphoglycolate and 3-phosphoglycerate in a process referred to as photorespiration.	Carboxydismutase,Ribulose Biphosphate Carboxylase-Oxygenase,Ribulose Diphosphate Carboxylase,Ribulosebiphosphate Carboxylase,Rubisco,1,5-Biphosphate Carboxylase-Oxygenase,Ribulose Biphosphate Carboxylase,Ribulose Bisphosphate Carboxylase,Ribulose-1,5-Biphosphate Carboxylase,Ribulose-1,5-Biphosphate Carboxylase-Oxygenase,Ribulose-1,5-Bisphosphate Carboxylase Small-Subunit,Ribulose-Bisphosphate Carboxylase Large Subunit,Ribulose-Bisphosphate Carboxylase Small Subunit,Rubisco Small Subunit,1,5 Biphosphate Carboxylase Oxygenase,Biphosphate Carboxylase-Oxygenase, Ribulose,Carboxylase Small-Subunit, Ribulose-1,5-Bisphosphate,Carboxylase, Ribulose Bisphosphate,Carboxylase, Ribulose Diphosphate,Carboxylase, Ribulose-1,5-Biphosphate,Carboxylase, Ribulose-Bisphosphate,Carboxylase, Ribulosebiphosphate,Carboxylase-Oxygenase, 1,5-Biphosphate,Carboxylase-Oxygenase, Ribulose Biphosphate,Carboxylase-Oxygenase, Ribulose-1,5-Biphosphate,Diphosphate Carboxylase, Ribulose,Ribulose 1,5 Biphosphate Carboxylase,Ribulose 1,5 Biphosphate Carboxylase Oxygenase,Ribulose 1,5 Bisphosphate Carboxylase Small Subunit,Ribulose Biphosphate Carboxylase Oxygenase,Ribulose Bisphosphate Carboxylase Large Subunit,Ribulose Bisphosphate Carboxylase Small Subunit,Small Subunit, Rubisco,Small-Subunit, Ribulose-1,5-Bisphosphate Carboxylase
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities