Glutamine amidotransferases are """"""""complex"""""""" enzymes with two different catalytic domains, each contributing to the catalysis of a single biochemical reaction. The family of sixteen enzymes catalyzes the transfer of amide nitrogen from glutamine (glutamine catalytic domain) to a variety of acceptor substrates (acceptor catalytic domain). Crystal structures have been determined for two amidotransferases of de novo purine biosynthesis. The structures of glutamine PRPP amidotransferase (GPATase) and GMP synthetase are prototypes for the two homologous families of glutamine catalytic domains, the Ntn and Triad families, respectively. The acceptor domains of both enzymes also represent homologous enzymes families, the phosphoribosyltransferases and the N-type ATP pyrophosphatases. Results from these first structures of amidotransferases have changed thinking about the enzyme family and led to new direction for future experiments. The most important new discovery of this work has been the means by which Ntn amidotransferases couple catalysis between glutamine and acceptor domains. The enzyme creates a channel for NH/3 between glutamine and acceptor active sites. Signal transduction between catalytic sites is triggered by substrate binding in the acceptor domain and involves formation of the NH/3 channel and activation of the glutamine domain. The proposed studies will investigate control and operation of the NH3 channel in GPATase and determine whether Triad amidotransferases also channel NH/3 between active sites. The product of GPATase is extremely unstable, and there is indirect evidence for channeling to GAP synthetase, the next enzyme of the purine biosynthetic pathway. This possibility will be investigated by structural studies of GAP synthetase and by mutagenesis experiments. The significant observations of the first two amidotransferases will be extended to other members of the enzyme family.
| Dodge, Greg J; Maloney, Finn P; Smith, Janet L (2018) Protein-protein interactions in ""cis-AT"" polyketide synthases. Nat Prod Rep 35:1082-1096 |
| Dodge, Greg J; Ronnow, Danialle; Taylor, Richard E et al. (2018) Molecular Basis for Olefin Rearrangement in the Gephyronic Acid Polyketide Synthase. ACS Chem Biol 13:2699-2707 |
| Skiba, Meredith A; Sikkema, Andrew P; Moss, Nathan A et al. (2018) Biosynthesis of t-Butyl in Apratoxin A: Functional Analysis and Architecture of a PKS Loading Module. ACS Chem Biol 13:1640-1650 |
| Skiba, Meredith A; Sikkema, Andrew P; Moss, Nathan A et al. (2017) A Mononuclear Iron-Dependent Methyltransferase Catalyzes Initial Steps in Assembly of the Apratoxin A Polyketide Starter Unit. ACS Chem Biol 12:3039-3048 |
| Skiba, Meredith A; Sikkema, Andrew P; Fiers, William D et al. (2016) Domain Organization and Active Site Architecture of a Polyketide Synthase C-methyltransferase. ACS Chem Biol 11:3319-3327 |
| Khare, Dheeraj; Hale, Wendi A; Tripathi, Ashootosh et al. (2015) Structural Basis for Cyclopropanation by a Unique Enoyl-Acyl Carrier Protein Reductase. Structure 23:2213-2223 |
| Smith, Amber Marie; Brown, William Clay; Harms, Etti et al. (2015) Crystal structures capture three states in the catalytic cycle of a pyridoxal phosphate (PLP) synthase. J Biol Chem 290:5226-39 |
| Bernard, Steffen M; Akey, David L; Tripathi, Ashootosh et al. (2015) Structural basis of substrate specificity and regiochemistry in the MycF/TylF family of sugar O-methyltransferases. ACS Chem Biol 10:1340-51 |
| Smith, Janet L; Skiniotis, Georgios; Sherman, David H (2015) Architecture of the polyketide synthase module: surprises from electron cryo-microscopy. Curr Opin Struct Biol 31:9-19 |
| Dutta, Somnath; Whicher, Jonathan R; Hansen, Douglas A et al. (2014) Structure of a modular polyketide synthase. Nature 510:512-7 |
Showing the most recent 10 out of 57 publications
