A family of highly conserved glycosomal 2-hydroxyacid dehydrogenases from Phytomonas sp.

Citation
Ad. Uttaro et al., A family of highly conserved glycosomal 2-hydroxyacid dehydrogenases from Phytomonas sp., J BIOL CHEM, 275(41), 2000, pp. 31833-31837
Citations number
30
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
00219258 → ACNP
Volume
275
Issue
41
Year of publication
2000
Pages
31833 - 31837
Database
ISI
SICI code
0021-9258(20001013)275:41<31833:AFOHCG>2.0.ZU;2-W
Abstract
Phytomonas sp. contains two malate dehydrogenase isoforms, a mitochondrial isoenzyme with a high specificity for oxaloacetate and a glycosomal isozyme that acts on a broad range of substrates (Uttaro, A. D., and Opperdoes, F. R, (1997) Mol. Biochem. Parasitol. 89, 51-59). Here, we show that the low s pecificity of the latter isoenzyme is the result of a number of recent gene duplications that gave rise to a family of glycosomal 2-hydroxyacid dehydr ogenase genes. Two of these genes were cloned, sequenced, and overexpressed in Escherichia coli. Although both gene products have 322 amino acids, sha re 90.4% identical residues, and have a similar hydrophobicity profile and net charge, their kinetic properties were strikingly different. One isoform behaved as a real malate dehydrogenase with a high specificity for oxaloac etate, whereas the other showed no activity with oxaloacetate but was able to reduce other oxoacids, such as phenyl pyruvate, 2-oxoisocaproate, 2-oxov alerate, 2-oxobutyrate, 2-oxo-4-methiolbutyrate, and pyruvate.