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Characterization of an oxaloacetate decarboxylase that belongs to the malic enzyme family
Author(s) -
Sender Pablo D,
Martı́n Mauricio G,
Peirú Salvador,
Magni Christian
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2004.06.038
Subject(s) - citrate synthase , decarboxylation , biochemistry , enzyme , chemistry , carboxy lyases , escherichia coli , biology , gene , catalysis
The citM gene from Lactococcus lactis CRL264 was 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 demonstrated by biochemical and genetic studies. The highest oxaloacetate decarboxylation activity was found at low pH in the presence of manganese, and the K m 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.