Modification of a thiol at the active site of the Ascaris suum NAD-malic enzyme results in changes in the rate-determining steps for oxidative decarboxylation of L-malate

Biochemistry ◽  
1991 ◽  
Vol 30 (23) ◽  
pp. 5764-5769 ◽  
Author(s):  
Sandhya R. Gavva ◽  
Ben G. Harris ◽  
Paul M. Weiss ◽  
Paul F. Cook
Keyword(s):  
Active Site ◽  
Malic Enzyme ◽  
Ascaris Suum ◽  
Oxidative Decarboxylation ◽  
Rate Determining Steps

Kinetic mechanism in the direction of oxidative decarboxylation for NAD-malic enzyme from Ascaris suum

Biochemistry ◽  
1984 ◽  
Vol 23 (23) ◽  
pp. 5446-5453 ◽  
Author(s):  
Sang Hoon Park ◽  
Dennis M. Kiick ◽  
Ben G. Harris ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Ascaris Suum ◽  
Kinetic Mechanism ◽  
Oxidative Decarboxylation

scholarly journals Unidirectional inhibition and activation of ‘malic’ enzyme of Solanum tuberosum by meso-tartrate

1975 ◽  
Vol 149 (2) ◽  
pp. 349-355 ◽  
Author(s):  
K H Do Nascimento ◽  
D D Davies ◽  
K D Patil
Keyword(s):  
Solanum Tuberosum ◽  
Organic Acids ◽  
Malic Acid ◽  
Active Site ◽  
Malic Enzyme ◽  
Control Site ◽  
Oxidative Decarboxylation ◽  
Reductive Carboxylation ◽  
Similar Explanation ◽  
Stimulation Of

A kinetic study of ‘malic’ enzyme (EC 1.1.1.40) from potato suggests that the mechanism is Ordered Bi Ter with NADP+ binding before malate, and NADPH binding before pyruvate and HCO3-. The analysis is complicated by the non-linearity that occurs in some of the plots. meso-Tartrate is shown to inhibit the oxidative decarboxylation of malate but to activate the reductive carboxylation of pyruvate. To explain these unidirectional effects it is suggested that the control site of ‘malic’ enzyme binds organic acids (including meso-tartrate) which activate the enzyme. meso-Tartrate, however, competes with malate for the active site and thus inhibits the oxidative decarboxylation of malate. Because meso-tartrate does not compete effectively with pyruvate for enzyme-NADPH, its binding at the control site leads to a stimulation of the carboxylation of pyruvate. A similar explanation is advanced for the observation that malic acid stimulates its own synthesis.

The crystal structure of the malic enzyme fromCandidatusPhytoplasma reveals the minimal structural determinants for a malic enzyme

2018 ◽  
Vol 74 (4) ◽  
pp. 332-340 ◽  
Author(s):  
C. E. Alvarez ◽  
F. Trajtenberg ◽  
N. Larrieux ◽  
M. Saigo ◽  
A. Golic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Malic Enzyme ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
Structure Design ◽  
Oxidative Decarboxylation ◽  
Functional Domain ◽  
High Concentration ◽  
Starting Point

Phytoplasmas are wall-less phytopathogenic bacteria that produce devastating effects in a wide variety of plants. Reductive evolution has shaped their genome, with the loss of many genes, limiting their metabolic capacities. Owing to the high concentration of C4compounds in plants, and the presence of malic enzyme (ME) in all phytoplasma genomes so far sequenced, the oxidative decarboxylation of L-malate might represent an adaptation to generate energy. Aster yellows witches'-broom (CandidatusPhytoplasma) ME (AYWB-ME) is one of the smallest of all characterized MEs, yet retains full enzymatic activity. Here, the crystal structure of AYWB-ME is reported, revealing a unique fold that differs from those of `canonical' MEs. AYWB-ME is organized as a dimeric species formed by intertwining of the N-terminal domains of the protomers. As a consequence of such structural differences, key catalytic residues such as Tyr36 are positioned in the active site of each protomer but are provided by the other protomer of the dimer. A Tyr36Ala mutation abolishes the catalytic activity, indicating the key importance of this residue in the catalytic process but not in the dimeric assembly. Phylogenetic analyses suggest that larger MEs (large-subunit or chimeric MEs) might have evolved from this type of smaller scaffold by gaining small sequence cassettes or an entire functional domain. TheCandidatusPhytoplasma AYWB-ME structure showcases a novel minimal structure design comprising a fully functional active site, making this enzyme an attractive starting point for rational genetic design.

scholarly journals Crystal structures of non-oxidative decarboxylases reveal a new mechanism of action with a catalytic dyad and structural twists

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Zeug ◽  
Nebojsa Markovic ◽  
Cristina V. Iancu ◽  
Joanna Tripp ◽  
Mislav Oreb ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Active Site ◽  
Enzyme Engineering ◽  
Base Catalysis ◽  
Oxidative Decarboxylation ◽  
Transition State Stabilization ◽  
Major Bottleneck ◽  
Hydroxybenzoic Acids ◽  
Potassium Binding ◽  
Β Sheet

AbstractHydroxybenzoic acids, like gallic acid and protocatechuic acid, are highly abundant natural compounds. In biotechnology, they serve as critical precursors for various molecules in heterologous production pathways, but a major bottleneck is these acids’ non-oxidative decarboxylation to hydroxybenzenes. Optimizing this step by pathway and enzyme engineering is tedious, partly because of the complicating cofactor dependencies of the commonly used prFMN-dependent decarboxylases. Here, we report the crystal structures (1.5–1.9 Å) of two homologous fungal decarboxylases, AGDC1 from Arxula adenivorans, and PPP2 from Madurella mycetomatis. Remarkably, both decarboxylases are cofactor independent and are superior to prFMN-dependent decarboxylases when heterologously expressed in Saccharomyces cerevisiae. The organization of their active site, together with mutational studies, suggests a novel decarboxylation mechanism that combines acid–base catalysis and transition state stabilization. Both enzymes are trimers, with a central potassium binding site. In each monomer, potassium introduces a local twist in a β-sheet close to the active site, which primes the critical H86-D40 dyad for catalysis. A conserved pair of tryptophans, W35 and W61, acts like a clamp that destabilizes the substrate by twisting its carboxyl group relative to the phenol moiety. These findings reveal AGDC1 and PPP2 as founding members of a so far overlooked group of cofactor independent decarboxylases and suggest strategies to engineer their unique chemistry for a wide variety of biotechnological applications.

Alternative Substrates for Malic Enzyme:  Oxidative Decarboxylation ofl-Aspartate†

Biochemistry ◽  
2002 ◽  
Vol 41 (40) ◽  
pp. 12200-12203 ◽  
Author(s):  
Dali Liu ◽  
Chi-Ching Hwang ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Oxidative Decarboxylation ◽  
Alternative Substrates

Tyrosyl Residue at or Near the Active Site of Maize NADP-malic Enzyme

1999 ◽  
Vol 36 (1-2) ◽  
pp. 225-231 ◽  
Author(s):  
S.R. Rao ◽  
B.G. Kamath ◽  
A.S. Bhagwat
Keyword(s):  
Active Site ◽  
Malic Enzyme

scholarly journals Identification and Characterization ofMAE1, the Saccharomyces cerevisiae Structural Gene Encoding Mitochondrial Malic Enzyme

1998 ◽  
Vol 180 (11) ◽  
pp. 2875-2882 ◽  
Author(s):  
Eckhard Boles ◽  
Patricia de Jong-Gubbels ◽  
Jack T. Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
Malic Enzyme ◽  
Fold Increase ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Oxidative Decarboxylation ◽  
Mrna Levels ◽  
Malic Enzyme Activity

ABSTRACT Pyruvate, a precursor for several amino acids, can be synthesized from phosphoenolpyruvate by pyruvate kinase. Nevertheless, pyk1 pyk2 mutants of Saccharomyces cerevisiae devoid of pyruvate kinase activity grew normally on ethanol in defined media, indicating the presence of an alternative route for pyruvate synthesis. A candidate for this role is malic enzyme, which catalyzes the oxidative decarboxylation of malate to pyruvate. Disruption of open reading frame YKL029c, which is homologous to malic enzyme genes from other organisms, abolished malic enzyme activity in extracts of glucose-grown cells. Conversely, overexpression ofYKL029c/MAE1 from the MET25 promoter resulted in an up to 33-fold increase of malic enzyme activity. Growth studies with mutants demonstrated that presence of either Pyk1p or Mae1p is required for growth on ethanol. Mutants lacking both enzymes could be rescued by addition of alanine or pyruvate to ethanol cultures. Disruption of MAE1 alone did not result in a clear phenotype. Regulation of MAE1 was studied by determining enzyme activities and MAE1 mRNA levels in wild-type cultures and by measuring β-galactosidase activities in a strain carrying a MAE1::lacZ fusion. Both in shake flask cultures and in carbon-limited chemostat cultures,MAE1 was constitutively expressed. A three- to fourfold induction was observed during anaerobic growth on glucose. Subcellular fractionation experiments indicated that malic enzyme in S. cerevisiae is a mitochondrial enzyme. Its regulation and localization suggest a role in the provision of intramitochondrial NADPH or pyruvate under anaerobic growth conditions. However, since null mutants could still grow anaerobically, this function is apparently not essential.

Metal Ion Activator on Intrinsic Isotope Effects of Hydride Transfer and Decarboxylation in the Reaction Catalyzed by the NAD-Malic Enzyme from Ascaris suum

Biochemistry ◽  
1995 ◽  
Vol 34 (10) ◽  
pp. 3253-3260 ◽  
Author(s):  
William E. Karsten ◽  
Sandya R. Gavva ◽  
Sang-Hoon Park ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Metal Ion ◽  
Ascaris Suum ◽  
Isotope Effects ◽  
Hydride Transfer
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