scholarly journals Trichoderma reesei Dehydrogenase, a Pyrroloquinoline Quinone-Dependent Member of Auxiliary Activity Family 12 of the Carbohydrate-Active Enzymes Database: Functional and Structural Characterization

2019 ◽  
Vol 85 (24) ◽  
Author(s):  
Annick Turbe-Doan ◽  
Eric Record ◽  
Vincent Lombard ◽  
Rajender Kumar ◽  
Anthony Levasseur ◽  
...  
Keyword(s):  
Trichoderma Reesei ◽  
Structural Characterization ◽  
Active Site ◽  
Pyrroloquinoline Quinone ◽  
Dimensional Structure ◽  
Crystallographic Structure ◽  
Coprinopsis Cinerea ◽  
Carbohydrate Active Enzymes ◽  
Content Type

ABSTRACT Pyrroloquinoline quinone (PQQ) is an ortho-quinone cofactor of several prokaryotic oxidases. Widely available in the diet and necessary for the correct growth of mice, PQQ has been suspected to be a vitamin for eukaryotes. However, no PQQ-dependent eukaryotic enzyme had been identified to use the PQQ until 2014, when a basidiomycete enzyme catalyzing saccharide dehydrogenation using PQQ as a cofactor was characterized and served to define auxiliary activity family 12 (AA12). Here we report the biochemical characterization of the AA12 enzyme encoded by the genome of the ascomycete Trichoderma reesei (TrAA12). Surprisingly, only weak activity against uncommon carbohydrates like l-fucose or d-arabinose was measured. The three-dimensional structure of TrAA12 reveals important similarities with bacterial soluble glucose dehydrogenases (sGDH). The enzymatic characterization and the structure solved in the presence of calcium confirm the importance of this ion in catalysis, as observed for sGDH. The structural characterization of TrAA12 was completed by modeling PQQ and l-fucose in the enzyme active site. Based on these results, the AA12 family of enzymes is likely to have a catalytic mechanism close to that of bacterial sGDH. IMPORTANCE Pyrroloquinoline quinone (PQQ) is an important cofactor synthesized by prokaryotes and involved in enzymatic alcohol and sugar oxidation. In eukaryotes, the benefit of PQQ as a vitamin has been suggested but never proved. Recently, the first eukaryotic enzyme using PQQ was characterized in the basidiomycete Coprinopsis cinerea, demonstrating that fungi are able to use PQQ as an enzyme cofactor. This discovery led to the classification of the fungal PQQ-dependent enzymes in auxiliary activity family 12 (AA12) of the Carbohydrate-Active Enzymes (CAZy) database (www.cazy.org) classification. In the present paper, we report on the characterization of the ascomycete AA12 enzyme from Trichoderma reesei (TrAA12). Our enzymatic and phylogenetic results show divergence with the only other member of the family characterized, that from the basidiomycete Coprinopsis cinerea. The crystallographic structure of TrAA12 shows similarities to the global active-site architecture of bacterial glucose dehydrogenases, suggesting a common evolution between the two families.

scholarly journals Structural Characterization of Two CO Molecules Bound to the Nitrogenase Active Site

2020 ◽  
Author(s):  
Trixia M. Buscagan ◽  
Kathryn A. Perez ◽  
Ailiena O. Maggiolo ◽  
Douglas C. Rees ◽  
Thomas Spatzal
Keyword(s):  
Structural Characterization ◽  
Active Site

scholarly journals Structural Features of a Bacteroidetes-Affiliated Cellulase Linked with a Polysaccharide Utilization Locus

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
A.E. Naas ◽  
A.K. MacKenzie ◽  
B. Dalhus ◽  
V.G.H. Eijsink ◽  
P.B. Pope
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Structural Features ◽  
Structure And Function ◽  
Dimensional Structure ◽  
Active Site Cleft ◽  
Polysaccharide Utilization Locus ◽  
And Function ◽  
Rumen Metagenome

Abstract Previous gene-centric analysis of a cow rumen metagenome revealed the first potentially cellulolytic polysaccharide utilization locus, of which the main catalytic enzyme (AC2aCel5A) was identified as a glycoside hydrolase (GH) family 5 endo-cellulase. Here we present the 1.8 Å three-dimensional structure of AC2aCel5A and characterization of its enzymatic activities. The enzyme possesses the archetypical (β/α)8-barrel found throughout the GH5 family and contains the two strictly conserved catalytic glutamates located at the C-terminal ends of β-strands 4 and 7. The enzyme is active on insoluble cellulose and acts exclusively on linear β-(1,4)-linked glucans. Co-crystallization of a catalytically inactive mutant with substrate yielded a 2.4 Å structure showing cellotriose bound in the −3 to −1 subsites. Additional electron density was observed between Trp178 and Trp254, two residues that form a hydrophobic “clamp”, potentially interacting with sugars at the +1 and +2 subsites. The enzyme’s active-site cleft was narrower compared to the closest structural relatives, which in contrast to AC2aCel5A, are also active on xylans, mannans and/or xyloglucans. Interestingly, the structure and function of this enzyme seem adapted to less-substituted substrates such as cellulose, presumably due to the insufficient space to accommodate the side-chains of branched glucans in the active-site cleft.

scholarly journals Structural Basis for Env Incorporation into HIV-1 Particles

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 114
Author(s):  
R. Elliot Murphy ◽  
Alexandra B. Samal ◽  
Gunnar Eastep ◽  
Ruba H. Ghanam ◽  
Peter E. Prevelige ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Late Phase ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Structural Basis ◽  
Membrane Interactions ◽  
Env Protein ◽  
Gag Assembly ◽  
Hiv 1

During the late phase of the HIV-1 replication cycle, the Gag polyproteins are transported to the plasma membrane (PM) for assembly. Gag targeting and assembly on the PM is dependent on interactions between its matrix (MA) domain and phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Subsequent to Gag assembly, the envelope (Env) protein is recruited to the PM for incorporation into virus particles. Evidence suggests that the incorporation of the Env protein is mediated by interactions between the MA domain of Gag and the cytoplasmic tail of the gp41 subunit of Env (gp41CT), a mechanism that remains to be elucidated. Trimerization of the MA domain of Gag appears to be an obligatory step for this interaction. The interplay between gp41CT, the MA trimer, and the membrane has yet to be determined. Our lab has pioneered methods and approaches to investigate, at the molecular level, how the retroviral MA domains of Gag interact with membranes, a key requirement for understanding the Gag assembly and Env incorporation. Herein, we devised innovative approaches that will enable the structural characterization of the gp41CT–MA–membrane interactions. We employed structural biology (NMR and cryo-electron microscopy, biophysical methods, and biochemical tools to generate a macromolecular picture of how the MA domain of Gag binds to the membrane and how it interacts with gp41CT. To this end, we: (i) determined the three-dimensional structure of HIV-1 gp41CT and characterized its interaction with the membrane, (ii) engineered trimeric constructs of gp41CT and the MA to recapitulate the native and functional states of the proteins, and (iii) utilized membrane nanodisc technology to anchor the MA and gp41CT proteins. Our studies will allow for a detailed structural characterization of the gp41CT–MA–membrane interactions, which will advance our knowledge of HIV-1 Gag assembly and Env incorporation.

scholarly journals A β-Alanine Catabolism Pathway Containing a Highly Promiscuous ω-Transaminase in the 12-Aminododecanate-Degrading Pseudomonas sp. Strain AAC

2016 ◽  
Vol 82 (13) ◽  
pp. 3846-3856 ◽  
Author(s):  
Matthew Wilding ◽  
Thomas S. Peat ◽  
Janet Newman ◽  
Colin Scott
Keyword(s):  
Conformational Changes ◽  
Active Site ◽  
Building Block ◽  
Protein A ◽  
Physiological Role ◽  
Substantial Contribution ◽  
Content Type ◽  
Nylon 12 ◽  
Dynamics Simulations

ABSTRACTWe previously isolated the transaminase KES23458 fromPseudomonassp. strain AAC as a promising biocatalyst for the production of 12-aminododecanoic acid, a constituent building block of nylon-12. Here, we report the subsequent characterization of this transaminase. It exhibits activity with a broad substrate range which includes α-, β-, and ω-amino acids, as well as α,ω-diamines and a number of other industrially relevant compounds. It is therefore a prospective candidate for the biosynthesis of a range of polyamide monomers. The crystal structure of KES23458 revealed that the protein forms a dimer containing a large active site pocket and unusual phosphorylated histidine residues. To infer the physiological role of the transaminase, we expressed, purified, and characterized a dehydrogenase from the same operon, KES23460. Unlike the transaminase, the dehydrogenase was shown to be quite selective, catalyzing the oxidation of malonic acid semialdehyde, formed from β-alanine transamination via KES23458. In keeping with previous reports, the dehydrogenase was shown to catalyze both a coenzyme A (CoA)-dependent reaction to form acetyl-CoA and a significantly slower CoA-independent reaction to form acetate. These findings support the original functional assignment of KES23458 as a β-alanine transaminase. However, a seemingly well-adapted active site and promiscuity toward unnatural compounds, such as 12-aminododecanoic acid, suggest that this enzyme could perform multiple functions forPseudomonassp. strain AAC.IMPORTANCEWe describe the characterization of an industrially relevant transaminase able to metabolize 12-aminododecanoic acid, a constituent building block of the widely used polymer nylon-12, and we report the biochemical and structural characterization of the transaminase protein. A physiological role for this highly promiscuous enzyme is proposed based on the characterization of a related gene from the host organism. Molecular dynamics simulations were carried out to compare the conformational changes in the transaminase protein to better understand the determinants of specificity in the protein. This study makes a substantial contribution that is of interest to the broad biotechnology and enzymology communities, providing insights into the catalytic activity of an industrially relevant biocatalyst as well as the biological function of this operon.

Synthesis and structural characterization of cross-linked histidine–phenol Cu(ii) complexes as cytochrome c oxidase active site models

2007 ◽  
pp. 3252 ◽  
Author(s):  
Kimberly N. White ◽  
Indranil Sen ◽  
Istvan Szundi ◽  
Yakira R. Landaverry ◽  
Lauren E. Bria ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Structural Characterization ◽  
Active Site

Spectroscopic, Redox, and Structural Characterization of the Ni-Labile and Nonlabile Forms of the Acetyl-CoA Synthase Active Site of Carbon Monoxide Dehydrogenase

1998 ◽  
Vol 120 (30) ◽  
pp. 7502-7510 ◽  
Author(s):  
William K. Russell ◽  
Christina M. V. Stålhandske ◽  
Jinqiang Xia ◽  
Robert A. Scott ◽  
Paul A. Lindahl
Keyword(s):  
Carbon Monoxide ◽  
Structural Characterization ◽  
Active Site ◽  
Carbon Monoxide Dehydrogenase ◽  
Acetyl Coa

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.

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