scholarly journals Crystal Structure of Bacterial Cystathionine Γ-Lyase in The Cysteine Biosynthesis Pathway of Staphylococcus aureus

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 656 ◽  
Author(s):  
Dukwon Lee ◽  
Soyeon Jeong ◽  
Jinsook Ahn ◽  
Nam-Chul Ha ◽  
Ae-Ran Kwon
Keyword(s):  
Crystal Structure ◽  
Staphylococcus Aureus ◽  
Active Site ◽  
Structural Changes ◽  
Enzymatic Reactions ◽  
Biosynthesis Pathway ◽  
Active Site Residues ◽  
Structural Comparison ◽  
General Base ◽  
Bond Network

Many enzymes require pyridoxal 5’-phosphate (PLP) as an essential cofactor and share active site residues in mediating diverse enzymatic reactions. Methionine can be converted into cysteine by cystathionine γ-lyases (CGLs) through a transsulfuration reaction dependent on PLP. In bacteria, MccB, also known as YhrB, exhibits CGL activity that cleaves the C–S bond of cystathionine at the γ position. In this study, we determined the crystal structure of MccB from Staphylococcus aureus in its apo- and PLP-bound forms. The structures of MccB exhibited similar molecular arrangements to those of MetC-mediating β-elimination with the same substrate and further illustrated PLP-induced structural changes in MccB. A structural comparison to MetC revealed a longer distance between the N-1 atom of the pyridine ring of PLP and the Oδ atom of the Asp residue, as well as a wider and more flexible active site environment in MccB. We also found a hydrogen bond network in Ser-water-Ser-Glu near the Schiff base nitrogen atom of the PLP molecule and propose the Ser-water-Ser-Glu motif as a general base for the γ-elimination process. Our study suggests the molecular mechanism for how homologous enzymes that use PLP as a cofactor catalyze different reactions with the same active site residues.

scholarly journals Crystal Structure and Desulfurization Mechanism of 2′-Hydroxybiphenyl-2-sulfinic Acid Desulfinase

2006 ◽  
Vol 281 (43) ◽  
pp. 32534-32539 ◽  
Author(s):  
Woo Cheol Lee ◽  
Takashi Ohshiro ◽  
Toshiyuki Matsubara ◽  
Yoshikazu Izumi ◽  
Masaru Tanokura
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Structural Changes ◽  
Hydrophobic Interactions ◽  
Rhodococcus Erythropolis ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Active Site Residues ◽  
Sulfinic Acid ◽  
New Family

The desulfurization of dibenzothiophene in Rhodococcus erythropolis is catalyzed by two monooxygenases, DszA and DszC, and a desulfinase, DszB. In the last step of this pathway, DszB hydrolyzes 2′-hydroxybiphenyl-2-sulfinic acid into 2-hydroxybiphenyl and sulfite. We report on the crystal structures of DszB and an inactive mutant of DszB in complex with substrates at resolutions of 1.8Å or better. The overall fold of DszB is similar to those of periplasmic substrate-binding proteins. In the substrate complexes, biphenyl rings of substrates are recognized by extensive hydrophobic interactions with the active site residues. Binding of substrates accompanies structural changes of the active site loops and recruits His60 to the active site. The sulfinate group of bound substrates forms hydrogen bonds with side chains of Ser27, His60, and Arg70, each of which is shown by site-directed mutagenesis to be essential for the activity. In our proposed reaction mechanism, Cys27 functions as a nucleophile and seems to be activated by the sulfinate group of substrates, whereas His60 and Arg70 orient the syn orbital of sulfinate oxygen to the sulfhydryl hydrogen of Cys27 and stabilize the negatively charged reaction intermediate. Cys, His, and Arg residues are conserved in putative proteins homologous to DszB, which are presumed to constitute a new family of desulfinases.

scholarly journals Threonine 57 is required for the post-translational activation ofEscherichia coliaspartate α-decarboxylase

2014 ◽  
Vol 70 (4) ◽  
pp. 1166-1172 ◽  
Author(s):  
Michael E. Webb ◽  
Briony A. Yorke ◽  
Tom Kershaw ◽  
Sarah Lovelock ◽  
Carina M. C. Lobley ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Site Directed Mutagenesis ◽  
Intramolecular Rearrangement ◽  
Directed Mutagenesis ◽  
Vitamin B ◽  
Biosynthesis Pathway ◽  
Serine Residue ◽  
Translational Activation

Aspartate α-decarboxylase is a pyruvoyl-dependent decarboxylase required for the production of β-alanine in the bacterial pantothenate (vitamin B5) biosynthesis pathway. The pyruvoyl group is formedviathe intramolecular rearrangement of a serine residue to generate a backbone ester intermediate which is cleaved to generate an N-terminal pyruvoyl group. Site-directed mutagenesis of residues adjacent to the active site, including Tyr22, Thr57 and Tyr58, reveals that only mutation of Thr57 leads to changes in the degree of post-translational activation. The crystal structure of the site-directed mutant T57V is consistent with a non-rearranged backbone, supporting the hypothesis that Thr57 is required for the formation of the ester intermediate in activation.

scholarly journals Crystal structure of yeast monothiol glutaredoxin Grx6 in complex with a glutathione-coordinated [2Fe–2S] cluster

2016 ◽  
Vol 72 (10) ◽  
pp. 732-737 ◽  
Author(s):  
Mohnad Abdalla ◽  
Ya-Nan Dai ◽  
Chang-Biao Chi ◽  
Wang Cheng ◽  
Dong-Dong Cao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Saccharomyces Cerevisiae ◽  
Sequence Alignment ◽  
Multiple Sequence Alignment ◽  
Active Site ◽  
Binding Pattern ◽  
Biological Functions ◽  
Structural Comparison ◽  
Multiple Sequence ◽  
Dimeric Structure

Glutaredoxins (Grxs) constitute a superfamily of proteins that perform diverse biological functions. TheSaccharomyces cerevisiaeglutaredoxin Grx6 not only serves as a glutathione (GSH)-dependent oxidoreductase and as a GSH transferase, but also as an essential [2Fe–2S]-binding protein. Here, the dimeric structure of the C-terminal domain of Grx6 (holo Grx6C), bridged by one [2Fe–2S] cluster coordinated by the active-site Cys136 and two external GSH molecules, is reported. Structural comparison combined with multiple-sequence alignment demonstrated that holo Grx6C is similar to the [2Fe–2S] cluster-incorporated dithiol Grxs, which share a highly conserved [2Fe–2S] cluster-binding pattern and dimeric conformation that is distinct from the previously identified [2Fe–2S] cluster-ligated monothiol Grxs.

Synthesis, characterization and molecular docking studies on some new N-substituted 2-phenylpyrido[2,3-d]pyrimidine derivatives

2021 ◽  
pp. 3846-3854
Author(s):  
Vivek B. Panchabhai ◽  
Santosh R. Butle ◽  
Parag G. Ingole
Keyword(s):  
Crystal Structure ◽  
Antibacterial Activity ◽  
Molecular Docking ◽  
Active Site ◽  
Docking Studies ◽  
Biotin Carboxylase ◽  
Active Site Residues ◽  
Pyrimidine Derivatives ◽  
Molecular Docking Studies ◽  
Novel Scaffold

We report a novel scaffold of N-substituted 2-phenylpyrido(2,3-d)pyrimidine derivatives with potent antibacterial activity by targeting this biotin carboxylase enzyme. The series of eighteen N-substituted 2-phenylpyrido(2,3-d)pyrimidine derivatives were synthesized, characterized and further molecular docking studied to determine the mode of binding and energy changes with the crystal structure of biotin carboxylase (PDB ID: 2V58) was employed as the receptor with compounds 6a-r as ligands. The results obtained from the simulation were obtained in the form of dock score; these values represent the minimum energies. Compounds 6d, 6l, 6n, 6o, 6r and 6i showed formation of hydrogen bonds with the active site residues and van Der Walls interactions with the biotin carboxylase enzyme in their molecular docking studies. This compound can be studied further and developed into a potential antibacterial lead molecule.

scholarly journals Crystal structure of a pyridoxal 5′-phosphate-dependent aspartate racemase derived from the bivalve mollusc Scapharca broughtonii

2017 ◽  
Vol 73 (12) ◽  
pp. 651-656 ◽  
Author(s):  
Taichi Mizobuchi ◽  
Risako Nonaka ◽  
Motoki Yoshimura ◽  
Katsumasa Abe ◽  
Shouji Takahashi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binding Site ◽  
Active Site ◽  
Metal Binding ◽  
Bivalve Mollusc ◽  
Active Site Residues ◽  
X Ray ◽  
Aspartate Racemase ◽  
Scapharca Broughtonii

Aspartate racemase (AspR) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that is responsible for D-aspartate biosynthesis in vivo. To the best of our knowledge, this is the first study to report an X-ray crystal structure of a PLP-dependent AspR, which was resolved at 1.90 Å resolution. The AspR derived from the bivalve mollusc Scapharca broughtonii (SbAspR) is a type II PLP-dependent enzyme that is similar to serine racemase (SR) in that SbAspR catalyzes both racemization and dehydration. Structural comparison of SbAspR and SR shows a similar arrangement of the active-site residues and nucleotide-binding site, but a different orientation of the metal-binding site. Superposition of the structures of SbAspR and of rat SR bound to the inhibitor malonate reveals that Arg140 recognizes the β-carboxyl group of the substrate aspartate in SbAspR. It is hypothesized that the aromatic proline interaction between the domains, which favours the closed form of SbAspR, influences the arrangement of Arg140 at the active site.

scholarly journals Enantioseparation, in vitro testing, and structural characterization of triple-binding reactivators of organophosphate-inhibited cholinesterases

2020 ◽  
Vol 477 (15) ◽  
pp. 2771-2790 ◽  
Author(s):  
Nikola Maraković ◽  
Anamarija Knežević ◽  
Igor Rončević ◽  
Xavier Brazzolotto ◽  
Zrinka Kovarik ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Proton Transfer ◽  
Structural Characterization ◽  
Active Site ◽  
In Vitro Testing ◽  
Active Site Residues

The enantiomers of racemic 2-hydroxyimino-N-(azidophenylpropyl)acetamide-derived triple-binding oxime reactivators were separated, and tested for inhibition and reactivation of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibited with tabun (GA), cyclosarin (GF), sarin (GB), and VX. Both enzymes showed the greatest affinity toward the methylimidazole derivative (III) of 2-hydroxyimino-N-(azidophenylpropyl)acetamide (I). The crystal structure was determined for the complex of oxime III within human BChE, confirming that all three binding groups interacted with active site residues. In the case of BChE inhibited by GF, oximes I (kr = 207 M−1 min−1) and III (kr = 213 M−1 min−1) showed better reactivation efficiency than the reference oxime 2-PAM. Finally, the key mechanistic steps in the reactivation of GF-inhibited BChE with oxime III were modeled using the PM7R6 method, stressing the importance of proton transfer from Nε of His438 to Oγ of Ser203 for achieving successful reactivation.

scholarly journals Crystal structure of maize serine racemase with pyridoxal 5′-phosphate

2016 ◽  
Vol 72 (3) ◽  
pp. 165-171 ◽  
Author(s):  
Lingling Zou ◽  
Yang Song ◽  
Chengliang Wang ◽  
Jiaqi Sun ◽  
Leilei Wang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Absorption Spectrometry ◽  
Serine Racemase ◽  
Type Ii ◽  
Active Site Residues ◽  
Structural Comparison ◽  
X Ray ◽  
Vancomycin Resistant ◽  
Serine Biosynthesis

Serine racemase (SR) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that is responsible for D-serine biosynthesisin vivo. The first X-ray crystal structure of maize SR was determined to 2.1 Å resolution and PLP binding was confirmed in solution by UV–Vis absorption spectrometry. Maize SR belongs to the type II PLP-dependent enzymes and differs from the SR of a vancomycin-resistant bacterium. The PLP is bound to each monomer by forming a Schiff base with Lys67. Structural comparison with rat and fission yeast SRs reveals a similar arrangement of active-site residues but a different orientation of the C-terminal helix.

scholarly journals Altered Orientation of Active Site Residues in Variants of Human Ferrochelatase. Evidence for a Hydrogen Bond Network Involved in Catalysis†

Biochemistry ◽  
2007 ◽  
Vol 46 (27) ◽  
pp. 7973-7979 ◽  
Author(s):  
Harry A. Dailey ◽  
Chia-Kuei Wu ◽  
Peter Horanyi ◽  
Amy E. Medlock ◽  
Wided Najahi-Missaoui ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Active Site ◽  
Hydrogen Bond Network ◽  
Active Site Residues ◽  
Bond Network

scholarly journals Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A β-Lactamase with a Monobactam Substrate

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Venu Gopal Vandavasi ◽  
Patricia S. Langan ◽  
Kevin L. Weiss ◽  
Jerry M. Parks ◽  
Jonathan B. Cooper ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Mechanism ◽  
Active Site Residues ◽  
Hydrogen Atoms ◽  
Content Type ◽  
X Ray Crystallography ◽  
General Base ◽  
Class A ◽  
Extended Spectrum ◽  
Enzyme Intermediate

ABSTRACT The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. The protonation states of active-site residues that are responsible for hydrolysis have been determined previously for the apo form of a CTX-M β-lactamase but not for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a class A β-lactamase in an acyl-enzyme complex with aztreonam, we directly observed most of the hydrogen atoms (as deuterium) within the active site. Although Lys 234 is fully protonated in the acyl intermediate, we found that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, as previously proposed.

Atomic resolution crystal structure of Sapp2p, a secreted aspartic protease fromCandida parapsilosis

2015 ◽  
Vol 71 (12) ◽  
pp. 2494-2504 ◽  
Author(s):  
Jiří Dostál ◽  
Adam Pecina ◽  
Olga Hrušková-Heidingsfeldová ◽  
Lucie Marečková ◽  
Iva Pichová ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Candida Parapsilosis ◽  
Chemical Interaction ◽  
Detailed Comparison ◽  
Aspartic Protease ◽  
Atomic Resolution ◽  
Active Site Residues ◽  
Aspartic Proteases ◽  
Pepstatin A

The virulence of theCandidapathogens is enhanced by the production of secreted aspartic proteases, which therefore represent possible targets for drug design. Here, the crystal structure of the secreted aspartic protease Sapp2p fromCandida parapsilosiswas determined. Sapp2p was isolated from its natural source and crystallized in complex with pepstatin A, a classical aspartic protease inhibitor. The atomic resolution of 0.83 Å allowed the protonation states of the active-site residues to be inferred. A detailed comparison of the structure of Sapp2p with the structure of Sapp1p, the most abundantC. parapsilosissecreted aspartic protease, was performed. The analysis, which included advanced quantum-chemical interaction-energy calculations, uncovered molecular details that allowed the experimentally observed equipotent inhibition of both isoenzymes by pepstatin A to be rationalized.

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