crystal structure of uroporphyrinogen iii synthase from an extremely thermophilic bacterium thermus thermophilus hb8 (wild type, native, form-2 crystal)
Uroporphyrinogen III synthase (EC4.2.1.75) is an enzyme involved in the metabolism of the cyclic tetrapyrrole compound porphyrin. It is involved in the conversion of hydroxymethyl bilane into uroporphyrinogen III. This enzyme catalyses the inversion of the final pyrrole unit (ring D) of the linear tetrapyrrole molecule, linking it to the first pyrrole unit (ring A), thereby generating a large macrocyclic structure, uroporphyrinogen III.[1] The enzyme folds into two alpha/beta domains connected by a beta-ladder, the active site being located between the two domains.[2]
Heme synthesis—note that some reactions occur in the cytoplasm and some in the mitochondrion (yellow)
A deficiency is associated with Gunther's disease, also known as congenital erythropoietic porphyria (CEP). This is an autosomal recessive inborn error of metabolism that results from the markedly deficient activity of uroporphyrinogen III synthase.[3]
^To-Figueras J, Badenas C, Mascaro JM, Madrigal I, Merino A, Bastida P, Lecha M, Herrero C (2007). "Study of the genotype-phenotype relationship in four cases of congenital erythropoietic porphyria". Blood Cells Mol. Dis. 38 (3): 242–6. doi:10.1016/j.bcmd.2006.12.001. PMID17270473.
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