Crystal Structure and Function of 5-Formaminoimidazole-4-carboxamide Ribonucleotide Synthetase from Methanocaldococcus jannaschii
| Autor: | Robert H. White, Steven E. Ealick, Yang Zhang |
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| Rok vydání: | 2007 |
| Předmět: |
Models
Molecular Inosine monophosphate Binding Sites Ribonucleotide biology ATP synthase Archaeal Proteins IMP cyclohydrolase Methanocaldococcus jannaschii Cyclohydrolase activity Methanococcaceae Ribonucleotides Crystallography X-Ray biology.organism_classification Biochemistry Phosphoribosylaminoimidazolecarboxamide Formyltransferase Protein Structure Secondary Article Protein Structure Tertiary biology.protein Pyrococcus furiosus Purine metabolism Phylogeny |
| Zdroj: | Biochemistry. 47:205-217 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi701406g |
| Popis: | Purine biosynthesis requires ten enzymatic steps in higher organisms while prokaryotes require an additional enzyme for step six. In most organisms steps nine and ten are catalyzed by the purH gene product, a bifunctional enzyme with both 5-formaminoimidazole-4-carboxamide-5′-monophosphate ribonucleotide (FAICAR) synthase and inosine monophosphate (IMP) cyclohydrolase activity. Recently it was discovered that Archaea utilize different enzymes to catalyze steps nine and ten. An ATP dependent FAICAR synthetase is encoded by the purP gene and IMP cyclohydrolase is encoded by the purO gene. We have determined the X-ray crystal structures of FAICAR synthetase from Methanocaldococcus jannaschii complexed with various ligands, including the tertiary substrate complex and product complex. The enzyme belongs to the ATP grasp superfamily and is predicted to use a formylphosphate intermediate formed by an ATP-dependent phosphorylation. In addition, we have determined the structures of a PurP ortholog from Pyrococcus furiosus, which is functionally unclassified, in three crystal forms. With approximately 50% sequence identity, P. furiosus PurP is structurally homologous to M. jannaschii PurP. A phylogenetic analysis was performed to explore the possible role of this functionally unclassified PurP. |
| Databáze: | OpenAIRE |
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