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Identification of domains involved in the allosteric regulation of cytosolic Arabidopsis thaliana NADP-malic enzymes.
- Source :
-
The FEBS journal [FEBS J] 2009 Oct; Vol. 276 (19), pp. 5665-77. Date of Electronic Publication: 2009 Sep 02. - Publication Year :
- 2009
-
Abstract
- The Arabidopsis thaliana genome contains four genes encoding NADP-malic enzymes (NADP-ME1-4). Two isoenzymes, NADP-ME2 and NADP-ME3, which are shown to be located in the cytosol, share a remarkably high degree of identity (90%). However, they display different expression patterns and show distinct kinetic properties, especially with regard to their regulation by effectors, in both the forward (malate oxidative decarboxylation) and reverse (pyruvate reductive carboxylation) reactions. In order to identify the domains in the primary structure that could be responsible for the regulatory differences, four chimeras between these isoenzymes were constructed and analysed. All chimeric versions exhibited the same native structures as the parental proteins. Analysis of the chimeras constructed indicated that the region from amino acid residue 303 to the C-terminal end of NADP-ME2 is critical for fumarate activation. However, the region flanked by amino acid residues 303 and 500 of NADP-ME3 is involved in the pH-dependent inhibition by high malate concentration. Furthermore, the N-terminal region of NADP-ME2 is necessary for the activation by succinate of the reverse reaction. Overall, the results show that NADP-ME2 and NADP-ME3 are able to distinguish and interact differently with similar C(4) acids as a result of minimal structural differences. Therefore, although the active sites of NADP-ME2 and NADP-ME3 are highly conserved, both isoenzymes acquire different allosteric sites, leading to the creation of proteins with unique regulatory mechanisms, probably best suited to the specific organ and developmental pattern of expression of each isoenzyme.
- Subjects :
- Allosteric Regulation
Allosteric Site genetics
Amino Acid Sequence
Arabidopsis genetics
Arabidopsis Proteins genetics
Base Sequence
Catalytic Domain genetics
Coenzyme A pharmacology
Cytosol enzymology
DNA Primers genetics
Enzyme Activation drug effects
Fumarates pharmacology
Genes, Plant
Green Fluorescent Proteins chemistry
Green Fluorescent Proteins genetics
Green Fluorescent Proteins metabolism
Hydrogen-Ion Concentration
Isoenzymes chemistry
Isoenzymes genetics
Isoenzymes metabolism
Kinetics
Malate Dehydrogenase
Malate Dehydrogenase (NADP+) genetics
Molecular Sequence Data
Protein Structure, Tertiary
Recombinant Fusion Proteins chemistry
Recombinant Fusion Proteins genetics
Recombinant Fusion Proteins metabolism
Sequence Homology, Amino Acid
Arabidopsis enzymology
Arabidopsis Proteins chemistry
Arabidopsis Proteins metabolism
Malate Dehydrogenase (NADP+) chemistry
Malate Dehydrogenase (NADP+) metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1742-4658
- Volume :
- 276
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- The FEBS journal
- Publication Type :
- Academic Journal
- Accession number :
- 19725876
- Full Text :
- https://doi.org/10.1111/j.1742-4658.2009.07258.x