Abstract
4-Amino-5-hydroxymethyl-2-methylpyrimidine phosphate (HMP-P) synthase catalyzes a complex rearrangement of 5-aminoimidazole ribonucleotide (AIR) to form HMP-P, the pyrimidine moiety of thiamine phosphate. We determined the three-dimensional structures of HMP-P synthase and its complexes with the product HMP-P and a substrate analog imidazole ribotide. The structure of HMP-P synthase reveals a homodimer in which each protomer comprises three domains: an N-terminal domain with a novel fold, a central (βα)8 barrel and a disordered C-terminal domain that contains a conserved CX 2CX4C motif, which is suggestive of a [4Fe-4S] cluster. Biochemical studies have confirmed that HMP-P synthase is iron sulfur cluster-dependent, that it is a new member of the radical SAM superfamily and that HMP-P and 5′-deoxyadenosine are products of the reaction. Mössbauer and EPR spectroscopy confirm the presence of one [4Fe-4S] cluster. Structural comparisons reveal that HMP-P synthase is homologous to a group of adenosylcobalamin radical enzymes. This similarity supports an evolutionary relationship between these two superfamilies.
Original language | English (US) |
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Pages (from-to) | 758-765 |
Number of pages | 8 |
Journal | Nature Chemical Biology |
Volume | 4 |
Issue number | 12 |
DOIs | |
State | Published - Dec 2008 |
Externally published | Yes |
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology