scholarly journals Symmetry-related residues as promising hotspots for the evolution of de novo oligomeric enzymes

2021 ◽  
Author(s):  
Jaeseung Yu ◽  
Jinsol Yang ◽  
Chaok Seok ◽  
Woon Ju Song
Keyword(s):  
Active Site ◽  
De Novo ◽  
Active Site Pocket

Symmetry-related residues located at the rotational axes can be promising hotspots for the evolution of de novo oligomeric enzymes even though they are distantly located from the active site pocket.

scholarly journals An enzymatic activation of formaldehyde for nucleotide methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Bou-Nader ◽  
Frederick W. Stull ◽  
Ludovic Pecqueur ◽  
Philippe Simon ◽  
Vincent Guérineau ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Crystallographic Structure ◽  
De Novo Synthesis ◽  
Active Site Residues ◽  
Enzymatic Activation ◽  
Enzyme Cofactors ◽  
Unique Ability

AbstractFolate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.

scholarly journals Chemical Stability of Ascorbic Acid Integrated into Commercial Products: A Review on Bioactivity and Delivery Technology

Antioxidants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 153
Author(s):  
Xin Yin ◽  
Kaiwen Chen ◽  
Hao Cheng ◽  
Xing Chen ◽  
Shuai Feng ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Active Site ◽  
De Novo ◽  
Food Matrix ◽  
De Novo Synthesis ◽  
Nutritional Characteristics ◽  
Gulonolactone Oxidase ◽  
Key Enzyme ◽  
Commercial Applications ◽  
Delivery Technology

The L-enantiomer of ascorbic acid is commonly known as vitamin C. It is an indispensable nutrient and plays a key role in retaining the physiological process of humans and animals. L-gulonolactone oxidase, the key enzyme for the de novo synthesis of ascorbic acid, is lacking in some mammals including humans. The functionality of ascorbic acid has prompted the development of foods fortified with this vitamin. As a natural antioxidant, it is expected to protect the sensory and nutritional characteristics of the food. It is thus important to know the degradation of ascorbic acid in the food matrix and its interaction with coexisting components. The biggest challenge in the utilization of ascorbic acid is maintaining its stability and improving its delivery to the active site. The review also includes the current strategies for stabilizing ascorbic acid and the commercial applications of ascorbic acid.

scholarly journals Enhancing a De Novo Enzyme Activity by Computationally-Focused, Ultra-Low-Throughput Sequence Screening

2020 ◽  
Author(s):  
Valeria A. Risso ◽  
Adrian Romero-Rivera ◽  
Luis I. Gutierrez-Rus ◽  
Mariano Ortega-Muñoz ◽  
Francisco Santoyo-Gonzalez ◽  
...  
Keyword(s):  
Directed Evolution ◽  
Active Site ◽  
De Novo ◽  
Enzymatic Reaction ◽  
Valence Bond ◽  
Computational Procedure ◽  
Enzyme Design ◽  
Computational Enzyme Design ◽  
Stability Ranking ◽  
Random Library

<div> <div> <div> <p>Directed evolution has revolutionized protein engineering. Still, enzyme optimization by random library screening remains a sluggish process, in large part due to futile probing of mutations that are catalytically neutral and/or impair stability and folding. FuncLib (funclib-weizmann.ac.il) is a novel automated computational procedure which uses phylogenetic analysis and Rosetta design to rank enzyme variants with multiple mutations, on the basis of a stability metric. Here, we use it to target the active site region of a minimalist-designed, de novo Kemp eliminase. The similarity between the Michaelis complex and transition state for the enzymatic reaction makes this a particularly challenging system to optimize. Yet, experimental screening of a very small number of active-site, multi-point variants at the top of the predicted stability ranking leads to catalytic efficiencies and turnover numbers (~2·104 M-1 s-1 and ~102 s-1) that compare well with modern natural enzymes, and that approach the catalysis levels for the best Kemp eliminases derived from extensive screening. This result illustrates the promise of FuncLib as a powerful tool with which to speed up directed evolution, by guiding screening to regions of the sequence space that encode stable and catalytically diverse enzymes. Empirical valence bond calculations reproduce the experimental activation energies for the optimized eliminases to within ~2 kcal·mol-1 and indicate that the improvements in activity are linked to better geometric preorganization of the active site. This raises the possibility of further enhancing the stability-guidance of FuncLib by EVB-based computational predictions of catalytic activity, as a generalized approach for computational enzyme design. </p> </div> </div> </div>

P4-286 The C-terminal PAL motif in presenilins constitutes part of the gamma-secretase active site pocket

2004 ◽  
Vol 25 ◽  
pp. S556-S557
Author(s):  
Jun Wang ◽  
Dirk Beher ◽  
Mark S. Shearman ◽  
Alison Goate
Keyword(s):  
Active Site ◽  
Gamma Secretase ◽  
Active Site Pocket

Site-Directed Mutagenesis of N5-Carboxyaminoimidazole Ribonucleotide Mutase (Class I PurE) in Bacillus anthracis

2011 ◽  
Vol 5 (1) ◽  
Author(s):  
M. Silas ◽  
N. Wolf ◽  
L.W.M. Fung
Keyword(s):  
Bacillus Anthracis ◽  
Active Site ◽  
De Novo ◽  
Structural Information ◽  
Site Directed Mutagenesis ◽  
Class I ◽  
Substrate Molecule ◽  
Antibiotic Development ◽  
Product Molecule ◽  
Future Experimentation

Anthrax, the infection caused by the Gram-positive pathogen Bacillus anthracis (B. anthracis), is fatal if untreated, and some strains of B. anthracis have been found to be resistant to currently available antibiotics. The development of broad spectrum antibiotics is needed to treat the resistive strains. In antibiotic development, we have targeted B. anthracis Class I PurE enzyme (Ba PurE) as a unique and necessary enzyme in the de novo purine biosynthesis pathway, since the inactivation of this gene prevents B. anthraci growth in human serum, resulting in decreased bacterial proliferation. To identify inhibitors to $Ba$PurE, structural information on the substrate binding to its active site is needed. However, it is difficult to obtain crystals of Ba PurE with the substrate molecule in its binding site since upon binding to PurE, the substrate molecule is converted to the product molecule. An alternative approach is to create mutants of PurE that exhibit no enzymatic activity and do not convert the substrate to product, but still allow the substrate to bind to the active site. Then, the structure of mutant PurE with bound substrate can be obtained. We have identified a histidine residue at position 70 as the target of mutation to give an inactive enzyme. After successfully preparing the recombinant protein H70N, we have found that it exhibited no enzyme activity. This mutant will be useful in future experimentation to identify inhibitors of Ba PurE.

scholarly journals Mechanism of pyranopterin ring formation in molybdenum cofactor biosynthesis

2015 ◽  
Vol 112 (20) ◽  
pp. 6347-6352 ◽  
Author(s):  
Bradley M. Hover ◽  
Nam K. Tonthat ◽  
Maria A. Schumacher ◽  
Kenichi Yokoyama
Keyword(s):  
Active Site ◽  
Biochemical Characterization ◽  
De Novo ◽  
Specific Binding ◽  
Molybdenum Cofactor ◽  
Enzyme Active Site ◽  
Complex Rearrangement ◽  
Cofactor Biosynthesis ◽  
Molybdenum Cofactor Biosynthesis

The molybdenum cofactor (Moco) is essential for all kingdoms of life, plays central roles in various biological processes, and must be biosynthesized de novo. During Moco biosynthesis, the characteristic pyranopterin ring is constructed by a complex rearrangement of guanosine 5′-triphosphate (GTP) into cyclic pyranopterin (cPMP) through the action of two enzymes, MoaA and MoaC (molybdenum cofactor biosynthesis protein A and C, respectively). Conventionally, MoaA was considered to catalyze the majority of this transformation, with MoaC playing little or no role in the pyranopterin formation. Recently, this view was challenged by the isolation of 3′,8-cyclo-7,8-dihydro-guanosine 5′-triphosphate (3′,8-cH2GTP) as the product of in vitro MoaA reactions. To elucidate the mechanism of formation of Moco pyranopterin backbone, we performed biochemical characterization of 3′,8-cH2GTP and functional and X-ray crystallographic characterizations of MoaC. These studies revealed that 3′,8-cH2GTP is the only product of MoaA that can be converted to cPMP by MoaC. Our structural studies captured the specific binding of 3′,8-cH2GTP in the active site of MoaC. These observations provided strong evidence that the physiological function of MoaA is the conversion of GTP to 3′,8-cH2GTP (GTP 3′,8-cyclase), and that of MoaC is to catalyze the rearrangement of 3′,8-cH2GTP into cPMP (cPMP synthase). Furthermore, our structure-guided studies suggest that MoaC catalysis involves the dynamic motions of enzyme active-site loops as a way to control the timing of interaction between the reaction intermediates and catalytically essential amino acid residues. Thus, these results reveal the previously unidentified mechanism behind Moco biosynthesis and provide mechanistic and structural insights into how enzymes catalyze complex rearrangement reactions.

scholarly journals Structural insights into enzymatic [4+2] aza-cycloaddition in thiopeptide antibiotic biosynthesis

2017 ◽  
Vol 114 (49) ◽  
pp. 12928-12933 ◽  
Author(s):  
Dillon P. Cogan ◽  
Graham A. Hudson ◽  
Zhengan Zhang ◽  
Taras V. Pogorelov ◽  
Wilfred A. van der Donk ◽  
...  
Keyword(s):  
Protein Design ◽  
Active Site ◽  
Active Sites ◽  
De Novo ◽  
Core Protein ◽  
Cycloaddition Reaction ◽  
Structural Similarity ◽  
Antibiotic Biosynthesis ◽  
Binding Studies ◽  
Nitrogenous Heterocycle

The [4+2] cycloaddition reaction is an enabling transformation in modern synthetic organic chemistry, but there are only limited examples of dedicated natural enzymes that can catalyze this transformation. Thiopeptides (or more formally thiazolyl peptides) are a class of thiazole-containing, highly modified, macrocyclic secondary metabolites made from ribosomally synthesized precursor peptides. The characteristic feature of these natural products is a six-membered nitrogenous heterocycle that is assembled via a formal [4+2] cycloaddition between two dehydroalanine (Dha) residues. This heteroannulation is entirely contingent on enzyme activity, although the mechanism of the requisite pyridine/dehydropiperidine synthase remains to be elucidated. The unusual aza-cylic product is distinct from the more common carbocyclic products of synthetic and biosynthetic [4+2] cycloaddition reactions. To elucidate the mechanism of cycloaddition, we have determined atomic resolution structures of the pyridine synthases involved in the biosynthesis of the thiopeptides thiomuracin (TbtD) and GE2270A (PbtD), in complex with substrates and product analogs. Structure-guided biochemical, mutational, computational, and binding studies elucidate active-site features that explain how orthologs can generate rigid macrocyclic scaffolds of different sizes. Notably, the pyridine synthases show structural similarity to the elimination domain of lanthipeptide dehydratases, wherein insertions of secondary structural elements result in the formation of a distinct active site that catalyzes different chemistry. Comparative analysis identifies other catalysts that contain a shared core protein fold but whose active sites are located in entirely different regions, illustrating a principle predicted from efforts in de novo protein design.

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