Crystal structure of alanine:glyoxylate aminotransferase and the relationship between genotype and enzymatic phenotype in primary hyperoxaluria type 1.
A deficiency of the liver-specific enzyme alanine:glyoxylate aminotransferase (AGT) is responsible for the potentially lethal hereditary kidney stone disease primary hyperoxaluria type 1 (PH1). Many of the mutations in the gene encoding AGT are associated with specific enzymatic phenotypes such as accelerated proteolysis (Ser205Pro), intra-peroxisomal aggregation (Gly41Arg), inhibition of pyridoxal phosphate binding and loss of catalytic activity (Gly82Glu), and peroxisome-to-mitochondrion mistargeting (Gly170Arg). Several mutations, including that responsible for AGT mistargeting, co-segregate and interact synergistically with a Pro11Leu polymorphism found at high frequency in the normal population. In order to gain further insights into the mechanistic link between genotype and enzymatic phenotype in PH1, we have determined the crystal structure of normal human AGT complexed to the competitive inhibitor amino-oxyacetic acid to 2.5A. Analysis of this structure allows the effects of these mutations and polymorphism to be rationalised in terms of AGT tertiary and quaternary conformation, and in particular it provides a possible explanation for the Pro11Leu-Gly170Arg synergism that leads to AGT mistargeting.
Zhang
Xiaoxuan
X
Department of Biology, University College London, Gower Street, London WC1E 6BT, UK.
Roe
S Mark
SM
Hou
Yanwen
Y
Bartlam
Mark
M
Rao
Zihe
Z
Pearl
Laurence H
LH
Danpure
Christopher J
CJ
D000483:Alleles; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D005838:Genotype; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D006959:Hyperoxaluria / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D010641:Phenotype; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D021381:Protein Transport; D011732:Pyridoxal Phosphate / Q000378:metabolism; D000637:Transaminases / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism
D011732:Pyridoxal Phosphate; D000637:Transaminases; C019635:Alanine-glyoxylate transaminase; D005990:Glycerol