The Mechanism of N10-Formyltetrahydrofolate Synthetase. Use of Human Thymidylate Synthase Variants to Characterize Asymmetric Ligand Binding and to Identify Novel Allosteric Inhibitors.
type: CreativeWork
description: Part I: N 10 -Formyltetrahydrofolate Synthetase (FTHFS), one of several folate enzymes, catalyzes the conversion of tetrahydrofolate (THF) to N 10 -formyltetrahydrofolate (fTHF) in an ATP dependent manner. In some organisms it is essential for C1 carbon fixation processes for cellular biosynthesis and has an increased concentration in bacteria that perform both acetogenesis, from the Wood-Ljungdahl pathway of autotrophic CO2 fixation, and purinolysis, through the glycine synthase/reductase pathway. The formation of fTHF occurs via a two-step process, which involves the formation of a formylphosphate (XPO) intermediate. The XPO intermediate has been proposed based on kinetic and spectroscopic experiments and confirmed through structure determination, which provided insight into the mechanism that FTHFS employs. Structures of FTHFS from the thermophilic homoacetogen, Moorella thermoacetica, with two sets of intermediates: ADP/XPO and ATPγS, as well as with two inhibitory substrate analogues, folate and ZD9331/XPO were determined to 2.5 Å, 2.84 Å, 3.0 Å, and 2.67 Å resolution respectively. Additionally, the native structure, originally determined at 2.5 Å resolution, was redetermined at 2.2 Å resolution. The enzyme is a tetramer, or a dimer of dimers, composed of four identical subunits. The bound nucleosides are observed within each of the subunits, totaling four per tetramer. Folate or the folate analogue, ZD9331, occupies the same space within the active site as the nucleosides. The presence and position of substrate, substrate analog, and intermediate within the active site supports the catalytic mechanism hypothesis that FTHFS works via a random bi uni uni bi ping-pong ter ter mechanism. Part II: Human thymidylate synthase (hTS) is a well-validated target in the chemotherapy of colorectal cancer and some other neoplasms. It catalyzes the transfer of a methyl group from methylenetetrahydrofolate (mTHF) to deoxyuridine monophosphate (dUMP) to form deoxythymidine mon…
abstract: Part I: N 10 -Formyltetrahydrofolate Synthetase (FTHFS), one of several folate enzymes, catalyzes the conversion of tetrahydrofolate (THF) to N 10 -formyltetrahydrofolate (fTHF) in an ATP dependent manner. In some organisms it is essential for C1 carbon fixation processes for cellular biosynthesis and has an increased concentration in bacteria that perform both acetogenesis, from the Wood-Ljungdahl pathway of autotrophic CO2 fixation, and purinolysis, through the glycine synthase/reductase pathway. The formation of fTHF occurs via a two-step process, which involves the formation of a formylphosphate (XPO) intermediate. The XPO intermediate has been proposed based on kinetic and spectroscopic experiments and confirmed through structure determination, which provided insight into the mechanism that FTHFS employs. Structures of FTHFS from the thermophilic homoacetogen, Moorella thermoacetica, with two sets of intermediates: ADP/XPO and ATPγS, as well as with two inhibitory substrate analogues, folate and ZD9331/XPO were determined to 2.5 Å, 2.84 Å, 3.0 Å, and 2.67 Å resolution respectively. Additionally, the native structure, originally determined at 2.5 Å resolution, was redetermined at 2.2 Å resolution. The enzyme is a tetramer, or a dimer of dimers, composed of four identical subunits. The bound nucleosides are observed within each of the subunits, totaling four per tetramer. Folate or the folate analogue, ZD9331, occupies the same space within the active site as the nucleosides. The presence and position of substrate, substrate analog, and intermediate within the active site supports the catalytic mechanism hypothesis that FTHFS works via a random bi uni uni bi ping-pong ter ter mechanism. Part II: Human thymidylate synthase (hTS) is a well-validated target in the chemotherapy of colorectal cancer and some other neoplasms. It catalyzes the transfer of a methyl group from methylenetetrahydrofolate (mTHF) to deoxyuridine monophosphate (dUMP) to form deoxythymidine mon…
author: Celeste, Lesa Rachel
keywords: Chemistry, Physical Sciences and Mathematics, Protein Crystallography
date published: 2012-01-01T08:00:00Z
date modified: 2026-07-24T04:38:23Z
provider: University of South Carolina
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of South Carolina