85-61-0Relevant articles and documents
Reconstitution of the pyridoxal 5′-phosphate (PLP) dependent enzyme serine palmitoyltransferase (SPT) with pyridoxal reveals a crucial role for the phosphate during catalysis
Beattie, Ashley E.,Clarke, David J.,Wadsworth, John M.,Lowther, Jonathan,Sin, Ho-Lam,Campopiano, Dominic J.
, p. 7058 - 7060 (2013)
The pyridoxal 5′-phosphate (PLP)-dependent enzyme serine palmitoyltransferase (SPT) is required for de novo sphingolipid biosynthesis. A previous study revealed a novel and unexpected interaction between the hydroxyl group of the l-serine substrate and the 5′-phosphate group of PLP. By using pyridoxal (PL), the dephosphorylated analogue of vitamin B6, we show here that this interaction is important for substrate specificity and optimal catalytic efficiency.
Structural basis for the activity and substrate specificity of fluoroacetyl-CoA thioesterase FIK
Dias, Marcio V. B.,Huang, Fanglu,Chirgadze, Dimitri Y.,Tosin, Manuela,Spiteller, Dieter,Dry, Emily F. V.,Leadlay, Peter F.,Spencer, Jonathan B.,Blundell, Tom L.
, p. 22495 - 22504 (2010)
The thioesterase FlK from the fluoroacetate-producing Streptomyces cattleya catalyzes the hydrolysis of fluoroacetyl-coenzyme A. This provides an effective self-defense mechanism, preventing any fluoroacetyl-coenzyme A formed from being further metabolized to 4-hydroxy-trans-aconitate, a lethal inhibitor of the tricarboxylic acid cycle. Remarkably, FlK does not accept acetyl-coenzyme A as a substrate. Crystal structure analysis shows that FlK forms a dimer, in which each subunit adopts a hot dog fold as observed for type II thioesterases. Unlike other type II thioesterases, which invariably utilize either an aspartate or a glutamate as catalytic base, we show by site-directed mutagenesis and crystallography that FlK employs a catalytic triad composed of Thr42, His76, and a water molecule, analogous to the Ser/Cys-His-acid triad of type I thioesterases. Structural comparison of FlK complexed with various substrate analogues suggests that the interaction between the fluorine of the substrate and the side chain of Arg120 located opposite to the catalytic triad is essential for correct coordination of the substrate at the active site and therefore accounts for the substrate specificity.
An evolutionarily conserved alternate metal ligand is important for activity in α-isopropylmalate synthase from Mycobacterium tuberculosis
Frantom, Patrick A.,Birman, Yuliya,Hays, Brittani N.,Casey, Ashley K.
, p. 1784 - 1789 (2014)
Members of the DRE-TIM metallolyase superfamily rely on an active-site divalent cation to catalyze various reactions involving the making and breaking of carbon-carbon bonds. While the identity of the metal varies, the binding site is well-conserved at the superfamily level with an aspartic acid and two histidine residues acting as ligands to the metal. Previous structural and bioinformatics results indicate that the metal can adopt an alternate architecture through the addition of an asparagine residue as a fourth ligand. This asparagine residue is strictly conserved in all members of the DRE-TIM metallolyase superfamily except fungal homocitrate synthase (HCS-lys) where it is replaced with isoleucine. The role of this additional metal ligand in α-isopropylmalate synthase from Mycobacterium tuberculosis (MtIPMS) has been investigated using site-directed mutagenesis. Substitution of the asparagine ligand with alanine or isoleucine results in inactive enzymes with respect to α-isopropylmalate formation. Control experiments suggest that the substitutions have not drastically affected the enzyme's structure indicating that the asparagine residue is essential for catalysis. Interestingly, all enzyme variants retained acetyl CoA hydrolysis activity in the absence of α-ketoisovalerate, similar to the wild-type enzyme. In contrast to the requirement of magnesium for α-isopropylmalate formation, hydrolytic activity could be inhibited by the addition of magnesium chloride in wild-type, D81E, and N321A MtIPMS, but not in the other variants studied. Attempts to rescue loss of activity in N321I MtIPMS by mimicking the fungal HCS active site through the D81E/N321I double variant were unsuccessful. This suggests epistatic constraints in evolution of function in IPMS and HCS-lys enzymes.
In Situ Assembly of Choline Acetyltransferase Ligands by a Hydrothiolation Reaction Reveals Key Determinants for Inhibitor Design
Wiktelius, Daniel,Allgardsson, Anders,Bergstr?m, Tomas,Hoster, Norman,Akfur, Christine,Forsgren, Nina,Lejon, Christian,Hedenstr?m, Mattias,Linusson, Anna,Ekstr?m, Fredrik
supporting information, p. 813 - 819 (2020/12/09)
The potential drug target choline acetyltransferase (ChAT) catalyses the production of the neurotransmitter acetylcholine in cholinergic neurons, T-cells, and B-cells. Herein, we show that arylvinylpyridiniums (AVPs), the most widely studied class of ChAT inhibitors, act as substrate in an unusual coenzyme A-dependent hydrothiolation reaction. This in situ synthesis yields an adduct that is the actual enzyme inhibitor. The adduct is deeply buried in the active site tunnel of ChAT and interactions with a hydrophobic pocket near the choline binding site have major implications for the molecular recognition of inhibitors. Our findings clarify the inhibition mechanism of AVPs, establish a drug modality that exploits a target-catalysed reaction between exogenous and endogenous precursors, and provide new directions for the development of ChAT inhibitors with improved potency and bioactivity.
Structural insights into the inhibition mechanism of human sterol O-acyltransferase 1 by a competitive inhibitor
Chang, Catherine C. Y.,Chang, Ta-Yuan,Chen, Lei,Chen, Si-Cong,Guan, Chengcheng,Kang, Yunlu,Luo, Tuoping,Nishi, Koji,Niu, Yange,Wu, Jing-Xiang
, (2020/05/27)
Sterol O-acyltransferase 1 (SOAT1) is an endoplasmic reticulum (ER) resident, multi-transmembrane enzyme that belongs to the membrane-bound O-acyltransferase (MBOAT) family. It catalyzes the esterification of cholesterol to generate cholesteryl esters for cholesterol storage. SOAT1 is a target to treat several human diseases. However, its structure and mechanism remain elusive since its discovery. Here, we report the structure of human SOAT1 (hSOAT1) determined by cryo-EM. hSOAT1 is a tetramer consisted of a dimer of dimer. The structure of hSOAT1 dimer at 3.5 ? resolution reveals that a small molecule inhibitor CI-976 binds inside the catalytic chamber and blocks the accessibility of the active site residues H460, N421 and W420. Our results pave the way for future mechanistic study and rational drug design targeting hSOAT1 and other mammalian MBOAT family members.
An Efficient Chemoenzymatic Synthesis of Coenzyme A and Its Disulfide
Mouterde, Louis M. M.,Stewart, Jon D.
, p. 954 - 959 (2016/06/13)
We have developed a chemoenzymatic route to coenzyme A (CoASH) and its disulfide that is amenable to gram-scale synthesis using standard laboratory equipment. By synthesizing the symmetrical disulfide of pantetheine (pantethine), we avoided the need to mask the reactive sulfhydryl and also prevented sulfur oxidation byproducts. No chromatography is required in our synthetic route to pantethine, which facilitates scale-up. Furthermore, we discovered that all three enzymes of the CoASH salvage pathway (pantetheine kinase, phosphopantetheine adenyltransferase, and dephospho-coenzyme A kinase) accept the disulfide of the natural substrates and functionalize both ends of the molecules. This yields CoA disulfide as the product of the enzymatic cascade, a much more stable form of the cofactor. Free CoASH can be prepared by in situ S-S reduction.
