Uroporphyrinogen
Decarboxylase (UROD)
Catie Hattan
Secondary & Quaternary Structure
Secondary Structure
• Human vs. Bacillus subtilis
• Human UROD
 51% helical (21 helices; 188
residues)
 10% beta sheet (10 strands; 40
residues)
• Bacillus subtilis
 50% helical (21 helices; 182
residues)
 8% beta sheet (11 strands; 29
residues)
Quaternary Structure
• Human vs. Bacillus subtilis
• Human UROD
 Homodimer
 1 Monomer 367 residues
• Bacillus subtilis
 Homodimer
 1 Monomer 359 residues
UROD “Clockwise” Decarboxylation
Major Isomers =7d, 6da, 5dab
Isomers=7a, 7b, 7c
Isomers=6ab, 6ac, 6bc, 6bd,
6cd
Isomers=5abc, 5acd,
5bc
P=CH2CH2CO2H
Residues Important to Enzyme Activity
BACTERIA1
BACTERIA2
BARLEY
TOBACCO
BACTERIA3
YEAST
RAT
HUMAN
ORANGUTAN
FROG
SALMON
BACTERIA1
BACTERIA2
BARLEY
TOBACCO
BACTERIA3
YEAST
RAT
HUMAN
ORANGUTAN
FROG
SALMON
Human UROD Monomer
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Alpha Helices=White PDB ID: 1R3Y
Beta Sheets=Blue
Arg 37=Purple
Asp 86=Yellow
Copro III Product=Green
PDB ID: 1R3Y
Active Site of
Enzyme
Bacillus subtilis Homodimer
PDB ID: 2INF
Human UROD Monomer in Comparison to Bacillus Subtilis
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Arg 37=Green
Arg 41=Red
Asp 86=Blue
Tyr 164=Purple
His 339=Pink
Ile 87=Magenta
Phe 154=Orange
Phe 217=Yellow
Copro III product=Gold
PDB ID: 13RY
Bacillus subtilis Monomer UROD in comparison to Human UROD
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Arg 29=Green
Arg 33=Red
Asp 78=Blue
Tyr 154=Purple
His 322=Pink
Ile 79=Magenta
Phe 144=Orange
Phe 207=Yellow
PDB ID: 2INF
Homodimer of Wild Type Human UROD superimposed with 3 Mutations of F-PCT
Yellow Mutation=D306Y
Blue Mutation=G318R
Green Mutation=K297N
Overlay Dimer=G318R Gray
Overlay Dimer=K297N Lime
Effects of Mutation in Patients with F-PCT
Medical Significance
Porphyrias
Porphyria Cutanea Tarda
• Most common type of
porphyria.
• It can be acquired and it
also can be inherited
(autosomal dominant).
Symptoms & Causes of PCT
• When exposed to the sun
the skin particularly on the
face and hands can be
damaged.
• PCT is caused by an
increased concentration of
porphyrins in the liver.
• PCT can be initiated by iron,
alcohol, HCV, HIV, and
estrogens.
Medical Significance Cont.
How is it diagnosed?
• PCT is diagnosed by
determining the amount of
porphyrins in the plasma.
• Also it can be diagnosed by
determining the presence
of hepta-carboxylate
intermediate in urine.
• In feces, isocoproporphyrin,
can be isolated to diagnose
PCT.
How is it treated?
• Routine blood draws equal
to ~1-2 pints of blood every
1-2 weeks. This is done to
reduce the amount of iron
in the liver. Target level of
ferritin is ~20ng/mL.
• And the use of drugs such
as chloroquine and
hydroxychloroquine help to
treat PCT.
Questions?
PCT Symptoms
•
Blistering occurs when
exposed to light.
•
Areas most effected by sun
exposure are the hands and
face.
References
1
2
Lash, T. D.; Mani, U. K.; Lyons, E. A.; Thientanavanich, P.; Jones, M. Normal and Abnormal Heme
Biosynthesis. 2. Synthesis and Metabolism of Type-III Pentacarboxylic Porphyrinogens: Further
Experimental Evidence for the Enzymatic Clockwise Decarboxylation of Uroporphyrinogen-III. J. Org.
Chem. 1999, 64, 478-487.
Jackson, A. H.; Sancovich, H. A.; Ferramola, A. M.; Evans, N.; Games, D. E.; Matlin, S. A.; Elder, G. H.;
Smith, S. G. Macrocyclic Intermediates in the
Biosynthesis of Porphyrins. Phil. Trans. R. Soc.
Lond. B 1976, 273, 191-206.
3
Lewis, Jr., C. A., and Wolfenden, R. (2008) Uroporphyrinogen Decarboxylation
as a Benchmark
for the catalytic proficiency of enzymes. Proc. Natl. Acad. Sci. U. S. A. 105, 17328-17333.
4
Pathway of Heme Biosynthesis. http://themedicalbiochemistrypage.org/heme(accessed Oct 30, 2014).
5
Jones, R. M., and Jordan, P. M. (1993) Purification and properties of the uroporphyrinogen
decarboxylase from Rhodobacter sphaeroides. Biochem. J. 293, 703-712.
6
Warby, C. A., and et. al. (2009) Structural and Kinetic Characterization of Mutant Human
Uroporphyrinogen Decarboxylases. Cell. Mol. Biol. 55, 40-45.
7
Porphyria Cutanea Tarda. http://www.porphyriafoundation.com/about-porphyria/types-ofporphyria/PCT (accessed Nov 18, 2014).
8
Porphyria Cutanea Tarda. http://www.onlinedermclinic.com/archive/porphyria-cutaneatarda#!prettyPhoto (accessed Nov 20, 2014).
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