Characterization of an oxaloacetate decarboxylase that belongs to the malic enzyme family

PABLO D SENDER; MAURICIO G MARTIN; SALVADOR PEIRÚ; CHRISTIAN MAGNI

FEBS LETTERS

ELSEVIER SCIENCE BV

Año: 2004 vol. 570 p. 217 - 222

0014-5793

demonstrated to encode for an oxaloacetate decarboxylase. The enzyme exhibits high levels of similarity to malic enzymes (MEs) from other organisms. CitM was expressed in Escherichia coli, purified and its oxaloacetate decarboxylase activity was demon- strated by biochemical and genetic studies. The highest oxalo- acetate decarboxylation activity was found at low pH in the presence of manganese, and the Km value for oxaloacetate was 0.52 % 0.03 mM. However, no malic activity was found for this enzyme. Our studies clearly show a new group of oxaloacetate decarboxylases associated with the citrate fermentation pathway in gram-positive bacteria. Furthermore, the essential catalytic residues were found to be conserved in all members of the ME family, suggesting a common mechanism for oxaloacetate decarboxylation.