| Structural highlights
Disease
[HEMH_HUMAN] Defects in FECH are the cause of erythropoietic protoporphyria (EPP) [MIM:177000]. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. EPP is a form of porphyria marked by excessive protoporphyrin in erythrocytes, plasma, liver and feces, and by widely varying photosensitive skin changes ranging from a burning or pruritic sensation to erythema, edema and wheals.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Function
[HEMH_HUMAN] Catalyzes the ferrous insertion into protoporphyrin IX.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Ferrochelatase catalyzes the terminal step in heme biosynthesis, the insertion of ferrous iron into protoporphyrin to form protoheme IX. The crystal structures of human ferrochelatase both with and without the protoporphyrin substrate bound have been determined previously. The substrate-free enzyme has an open active site pocket, while in the substrate-bound enzyme, the active site pocket is closed around the porphyrin macrocycle and a number of active site residues have reoriented side chains. To understand how and why these structural changes occur, we have substituted three amino acid residues (H263, H341, and F337) whose side chains occupy different spatial positions in the substrate-free versus substrate-bound ferrochelatases. The catalytic and structural properties of ferrochelatases containing the amino acid substitutions H263C, H341C, and F337A were examined. It was found that in the H263C and H341C variants, but not the F337A variant enzymes, the side chains of N75, M76, R164, H263, F337, H341, and E343 are oriented in a fashion similar to what is found in ferrochelatase with the bound porphyrin substrate. However, all of the variant forms possess open active site pockets which are found in the structure of porphyrin-free ferrochelatase. Thus, while the interior walls of the active site pocket are remodeled in these variants, the exterior lips remain unaltered in position. One possible explanation for this collective reorganization of active site side chains is the presence of a hydrogen bond network among H263, H341, and E343. This network is disrupted in the variants by alteration of H263C or H341C. In the substrate-bound enzyme, the formation of a hydrogen bond between H263 and a pyrrole nitrogen results in disruption of the network. The possible role of this network in catalysis is discussed.
Altered orientation of active site residues in variants of human ferrochelatase. Evidence for a hydrogen bond network involved in catalysis.,Dailey HA, Wu CK, Horanyi P, Medlock AE, Najahi-Missaoui W, Burden AE, Dailey TA, Rose J Biochemistry. 2007 Jul 10;46(27):7973-9. Epub 2007 Jun 14. PMID:17567154[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lamoril J, Boulechfar S, de Verneuil H, Grandchamp B, Nordmann Y, Deybach JC. Human erythropoietic protoporphyria: two point mutations in the ferrochelatase gene. Biochem Biophys Res Commun. 1991 Dec 16;181(2):594-9. PMID:1755842
- ↑ Brenner DA, Didier JM, Frasier F, Christensen SR, Evans GA, Dailey HA. A molecular defect in human protoporphyria. Am J Hum Genet. 1992 Jun;50(6):1203-10. PMID:1376018
- ↑ Sarkany RP, Alexander GJ, Cox TM. Recessive inheritance of erythropoietic protoporphyria with liver failure. Lancet. 1994 Jun 4;343(8910):1394-6. PMID:7910885
- ↑ Imoto S, Tanizawa Y, Sato Y, Kaku K, Oka Y. A novel mutation in the ferrochelatase gene associated with erythropoietic protoporphyria. Br J Haematol. 1996 Jul;94(1):191-7. PMID:8757534
- ↑ Rufenacht UB, Gouya L, Schneider-Yin X, Puy H, Schafer BW, Aquaron R, Nordmann Y, Minder EI, Deybach JC. Systematic analysis of molecular defects in the ferrochelatase gene from patients with erythropoietic protoporphyria. Am J Hum Genet. 1998 Jun;62(6):1341-52. PMID:9585598 doi:S0002-9297(07)62775-X
- ↑ Gouya L, Schneider-Yin X, Rufenacht U, Herrero C, Lecha M, Mascaro JM, Puy H, Deybach JC, Minder EI. Mutations in the ferrochelatase gene of four Spanish patients with erythropoietic protoporphyria. J Invest Dermatol. 1998 Sep;111(3):406-9. PMID:9740232 doi:10.1046/j.1523-1747.1998.00327.x
- ↑ Schneider-Yin X, Gouya L, Dorsey M, Rufenacht U, Deybach JC, Ferreira GC. Mutations in the iron-sulfur cluster ligands of the human ferrochelatase lead to erythropoietic protoporphyria. Blood. 2000 Aug 15;96(4):1545-9. PMID:10942404
- ↑ Rufenacht UB, Gregor A, Gouya L, Tarczynska-Nosal S, Schneider-Yin X, Deybach JC. New missense mutation in the human ferrochelatase gene in a family with erythropoietic protoporphyria: functional studies and correlation of genotype and phenotype. Clin Chem. 2001 Jun;47(6):1112-3. PMID:11375302
- ↑ Poh-Fitzpatrick MB, Wang X, Anderson KE, Bloomer JR, Bolwell B, Lichtin AE. Erythropoietic protoporphyria: altered phenotype after bone marrow transplantation for myelogenous leukemia in a patient heteroallelic for ferrochelatase gene mutations. J Am Acad Dermatol. 2002 Jun;46(6):861-6. PMID:12063482
- ↑ Wiman A, Floderus Y, Harper P. Novel mutations and phenotypic effect of the splice site modulator IVS3-48C in nine Swedish families with erythropoietic protoporphyria. J Hum Genet. 2003;48(2):70-6. PMID:12601550 doi:10.1007/s100380300009
- ↑ Whatley SD, Mason NG, Khan M, Zamiri M, Badminton MN, Missaoui WN, Dailey TA, Dailey HA, Douglas WS, Wainwright NJ, Elder GH. Autosomal recessive erythropoietic protoporphyria in the United Kingdom: prevalence and relationship to liver disease. J Med Genet. 2004 Aug;41(8):e105. PMID:15286165 doi:10.1136/jmg.2003.016121
- ↑ Aurizi C, Schneider-Yin X, Sorge F, Macri A, Minder EI, Biolcati G. Heterogeneity of mutations in the ferrochelatase gene in Italian patients with erythropoietic protoporphyria. Mol Genet Metab. 2007 Apr;90(4):402-7. Epub 2006 Dec 29. PMID:17196862 doi:S1096-7192(06)00355-6
- ↑ Dailey HA, Wu CK, Horanyi P, Medlock AE, Najahi-Missaoui W, Burden AE, Dailey TA, Rose J. Altered orientation of active site residues in variants of human ferrochelatase. Evidence for a hydrogen bond network involved in catalysis. Biochemistry. 2007 Jul 10;46(27):7973-9. Epub 2007 Jun 14. PMID:17567154 doi:10.1021/bi700151f
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