1. Molybdenum in Action Naomi Bryner

2. Overview • General molybdenum importance • Enzymes that use Moco • 3 families • Biosynthetic pathway • Genes involved • Deficiency • Current Literature

3. Molybdenum • Nitrogenase • Fix N2(g) • In bacteria • Molybdopterin • Cofactor for Mo • Can beW instead • Same group

4. Enzyme families that use Moco • Sulfite oxidase • DMSO reductase • Xanthine oxidase • Catalyzes oxygen atom transfer • Square pyramidal coordination • Eukarya • Rat liver • Sulfite oxidase, nitrate reductase

5. Enzyme families that use Moco • Sulfite oxidase • DMSO reductase • Xanthine oxidase • Catalyzes oxygen atom transfer • Distorted trigonal prismatic coordination • Bacteria, Archaea • Rhodobactersphaeroides • DMSO reductase, biotin-S-oxide reductase, trimethylamine-N-oxide reductase, nitrate reductase, formate dehydrogenase, polysulfide reductase, arsenite oxidase, formylmethanofuran dehydrogenase

6. Enzyme families that use Moco • Sulfite oxidase • DMSO reductase • Xanthine oxidase • Catalyzes oxidative hydroxylation • Distorted square-pyramidal coordination • All domains • Desulfovibriogigas • Xanthine oxidase, xanthine dehydrogenase, aldehyde oxidase, aldehyde oxidoreductase, formate dehydrogenase, CO dehydrogenase, quinolone-2-oxidoreductase, isoquinoline 1-oxidoreductase, quinoline-4-carboxylate-2-oxidoreductase, quinaldine-4-oxidoreductase, quinaldic acid 4-oxidoreductase, nicotinic acid hydroxylase, 6-hydroxynicotinate hydroxylase, (2R)-hydroxycarboxylateoxidoreductase

7. Biosynthetic Pathway • MOCS1 • On c-some 6 • MOCS1A • MOCS1AB/MOCS1B • Separated by 15 nt cPMP = ‘precursor Z’ • MOCS2 • On c-some 5 • MOCS2A • MOCS2B

8. Biosynthetic Pathway • MOCS3 • On c-some 20 • Mutations = OK MPT  no Mo! • Gephyrin (GPHN) • On c-some 16 • 3’ side first • 5’ side second

9. Moco Deficiency • Lost activity • Sulfite oxidase • Aldehyde oxidase • Xanthine oxidoreductase • Disease causing mutations • MOCS1, MOCS2, GPHN • Autosomal recessive • Type A • First step in pathway blocked (no cPMP) • Type B • Second step in pathway blocked (no MPT) • Result • Sulfite accumulation • Can cross BBB

10. Current Lit - Medicinal • 2013 Journal of Medicinal Chemistry - Synthesis of cyclic pyranopterin monophosphate, a biosynthetic intermediate in the molybdenum cofactor pathway • Synthesis of cPMP for general Moco production • In vitro comparison with bacterial cPMP • Equally effective • 2009 Nucleosides, Nucleotides, and Nucleic Acids – A Turkish case with molybdenum cofactor deficiency • Sequenced patient’s Moco coding regions • Sequenced family (mother, father, siblings) • Family heterozygous, patient homozygous

11. Current Lit - Computational • 2012 Inorganic Chemistry - Substrate and metal control of barrier heights for oxo transfer to Mo and W bis-dithioline sites • DMSO reductase kinetics with altered ligands • Studying Me-oxo transfers will help find rate-determining step • Transition step 2 is limiting, depends on substrate and metal • 2008 Journal of Inorganic Biochemistry – Synthesis, electrochemistry, geometric and electronic structure of oxo-molybdenum compounds involved in an oxygen atom transferring system • Sulfite oxidase electronic structure with OPMe3 ligand • Redox potential was separated [375 mV from Mo(V)Mo(IV)] • This ligand could allow for atom transfer reaction investigation

12. References • Santamaria-Araujo, J.; Wray, V.; Schwarz, G. Structure and stability of the molybdenum cofactor intermediate cyclic pyranopterin monophosphate. Journal of Biological Inorganic Chemistry, 2012, 17, 113-122. • Clinch, K.; Watt, D.; Dixon, R.; Baars, S.; Gainsford, G.; Tiwari, A.; Schwarz, G.; Saotome, Y.; Storek, M.; Belaidi, A.; Santamaria-Araujo, J. Synthesis of cyclic pyranopterin monophosphate, a biosynthetic intermediate in the molybdenum cofactor pathway. Journal of Medicinal Chemistry, 2013, 56, 1730-1738. • Hille, R. The mononuclear molybdenum enzymes. Chemical Reviews, 1996, 96, 2757-2816. • Tenderholt, A.; Hodgson, K.; Hedman, B.; Holm, R.; Solomon, E. Substrate and metal control of barrier heights for oxo transfer to Mo and W bis-dithioline sites. Inorganic Chemistry, 2012, 51, 3436-3442. • Ichicda, K.; Ibrahim Aydin, H.; Hosoyamada, M.; SerapKalkanoglu, H.; Dursun, A.; Ohno, I.; Coskun, T.; Tokatli, A.; Shibasaki, T.; Hosoya, T. A Turkish case with molybdenum cofactor deficiency. Nucleosides, Nucleotides, and Nucleic Acids, 2006, 25, 1087-1091. • Reiss, J.; Johnson, J. Mutations in the molybdenum cofactor biosynthetic genes MOCS1, MOCS2, MOCS3, and GEPH. Human Mutation, 2003, 21, 569-576. • Reiss, J. Genetics of molybdenum cofactor deficiency. Human Genetics, 2000, 106, 157-163. • Schwarz, G. Molybdenum cofactor biosynthesis and deficiency. Cellular and Molecular Life Sciences, 2005, 62, 2792-2810.9 • Sengar, R.; Nemykin, V.; Basu, P. Synthesis, electrochemistry, geometric and electronic structure of oxo-molybdenum compounds involved in an oxygen atom transferring system. Journal of Inorganic Biochemistry, 2008, 102 (4), 748-756.