RT Journal Article
T1 Caenorhabditis elegans AGXT-1 is a mitochondrial and temperature-adapted ortholog of peroxisomal human AGT1: New insights into between-species divergence in glyoxylate metabolism.
A1 Mesa-Torres, Noel
A1 Calvo, Ana C
A1 Oppici, Elisa
A1 Titelbaum, Nicholas
A1 Montioli, Riccardo
A1 Miranda-Vizuete, Antonio
A1 Cellini, Barbara
A1 Salido, Eduardo
A1 Pey, Angel L
K1 Conformational disease
K1 Enzyme kinetics
K1 Primary hyperoxaluria
K1 Protein stability
K1 Substrate specificity
AB In humans, glyoxylate is an intermediary product of metabolism, whose concentration is finely balanced. Mutations in peroxisomal alanine:glyoxylate aminotransferase (hAGT1) cause primary hyperoxaluria type 1 (PH1), which results in glyoxylate accumulation that is converted to toxic oxalate. In contrast, glyoxylate is used by the nematode Caenorhabditis elegans through a glyoxylate cycle to by-pass the decarboxylation steps of the tricarboxylic acid cycle and thus contributing to energy production and gluconeogenesis from stored lipids. To investigate the differences in glyoxylate metabolism between humans and C. elegans and to determine whether the nematode might be a suitable model for PH1, we have characterized here the predicted nematode ortholog of hAGT1 (AGXT-1) and compared its molecular properties with those of the human enzyme. Both enzymes form active PLP-dependent dimers with high specificity towards alanine and glyoxylate, and display similar three-dimensional structures. Interestingly, AGXT-1 shows 5-fold higher activity towards the alanine/glyoxylate pair than hAGT1. Thermal and chemical stability of AGXT-1 is lower than that of hAGT1, suggesting temperature-adaptation of the nematode enzyme linked to the lower optimal growth temperature of C. elegans. Remarkably, in vivo experiments demonstrate the mitochondrial localization of AGXT-1 in contrast to the peroxisomal compartmentalization of hAGT1. Our results support the view that the different glyoxylate metabolism in the nematode is associated with the divergent molecular properties and subcellular localization of the alanine:glyoxylate aminotransferase activity.
PB Elsevier BV
SN 0006-3002
YR 2016
FD 2016-05-11
LK http://hdl.handle.net/10668/10080
UL http://hdl.handle.net/10668/10080
LA en
NO Mesa-Torres N, Calvo AC, Oppici E, Titelbaum N, Montioli R, Miranda-Vizuete A, et al. Caenorhabditis elegans AGXT-1 is a mitochondrial and temperature-adapted ortholog of peroxisomal human AGT1: New insights into between-species divergence in glyoxylate metabolism. Biochim Biophys Acta. 2016 Sep;1864(9):1195-1205.
DS RISalud
RD Apr 19, 2025