scholarly journals Characterizing Activity and Thermostability of GH5 Cellulase Chimeras from Mesophilic and Thermophilic Parents

2018 ◽  
Author(s):  
Fei Zheng ◽  
Josh V. Vermaas ◽  
Jie Zheng ◽  
Yuan Wang ◽  
Tao Tu ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Rational Design ◽  
Enzyme Stability ◽  
Catalytic Efficiency ◽  
Industrial Applications ◽  
Essential Property ◽  
Tim Barrel ◽  
Dynamics Simulations ◽  
Temperature Optima ◽  
Hybrid Enzymes

ABSTRACTCellulases from glycoside hydrolase (GH) family 5 are key enzymes in the degradation of diverse polysaccharide substrates and are used in industrial enzyme cocktails to break down biomass. The GH5 family shares a canonical (βα)8-barrel structure, where each (βα) module is essential for the enzyme stability and activity. Despite their shared topology, the thermostability of GH5 enzymes can vary significantly, and highly thermostable variants are often sought for industrial applications. Based on a previously characterized thermophilic GH5 cellulase from Talaromyces emersonii (TeEgl5A, with an optimal temperature of 90°C), we created ten hybrid enzymes with the mesophilic cellulase from Prosthecium opalus (PoCel5) to determine which elements are responsible for enhanced thermostability. Five of the expressed hybrid enzymes exhibit enzyme activity. Two of these hybrids exhibited pronounced increases in the temperature optima (10 and 20°C), T50 (15 and 19°C), Tm (16.5 and 22.9°C), and extended half life, t1/2 (~240- and 650-fold at 55°C) relative to the mesophilic parent enzyme, and demonstrated improved catalytic efficiency on selected substrates. The successful hybridization strategies were validated experimentally in another GH5 cellulase from Aspergillus nidulans (AnCel5), which demonstrated a similar increase in thermostability. Based on molecular dynamics simulations (MD) of both PoCel5 and TeEgl5A parent enzymes as well as their hybrids, we hypothesize that improved hydrophobic packing of the interface between α2 and α3 is the primary mechanism by which the hybrid enzymes increase their thermostability relative to the mesophilic parent PoCel5.IMPORTANCEThermal stability is an essential property of enzymes in many industrial biotechnological applications, as high temperatures improve bioreactor throughput. Many protein engineering approaches, such as rational design and directed evolution, have been employed to improve the thermal properties of mesophilic enzymes. Structure-based recombination has also been used to fuse TIM-barrel fragments and even fragments from unrelated folds, to generate new structures. However, there are not many research on GH5 cellulases. In this study, two GH5 cellulases, which showed TIM-barrel structure, PoCel5 and TeEgl5A with different thermal properties were hybridized to study the roles of different (βα) motifs. This work illustrates the role that structure guided recombination can play in helping to identify sequence function relationships within GH5 enzymes by supplementing natural diversity with synthetic diversity.

scholarly journals Activity and Thermostability of GH5 Endoglucanase Chimeras from Mesophilic and Thermophilic Parents

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Fei Zheng ◽  
Josh V. Vermaas ◽  
Jie Zheng ◽  
Yuan Wang ◽  
Tao Tu ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Rational Design ◽  
Catalytic Efficiency ◽  
Md Simulations ◽  
Industrial Applications ◽  
Glycoside Hydrolase Family ◽  
Essential Property ◽  
Content Type ◽  
Tim Barrel ◽  
Hybrid Enzymes

ABSTRACT Cellulases from glycoside hydrolase family 5 (GH5) are key endoglucanase enzymes in the degradation of diverse polysaccharide substrates and are used in industrial enzyme cocktails to break down biomass. The GH5 family shares a canonical (βα)8-barrel structure, where each (βα) module is essential for the enzyme’s stability and activity. Despite their shared topology, the thermostability of GH5 endoglucanase enzymes can vary significantly, and highly thermostable variants are often sought for industrial applications. Based on the previously characterized thermophilic GH5 endoglucanase Egl5A from Talaromyces emersonii (TeEgl5A), which has an optimal temperature of 90°C, we created 10 hybrid enzymes with elements of the mesophilic endoglucanase Cel5 from Stegonsporium opalus (SoCel5) to determine which elements are responsible for enhanced thermostability. Five of the expressed hybrid enzymes exhibit enzyme activity. Two of these hybrids exhibited pronounced increases in the temperature optimum (10 and 20°C), the temperature at which the protein lost 50% of its activity (T50) (15 and 19°C), and the melting temperature (Tm) (16.5 and 22.9°C) and extended half-lives (t1/2) (∼240- and 650-fold at 55°C) relative to the values for the mesophilic parent enzyme and demonstrated improved catalytic efficiency on selected substrates. The successful hybridization strategies were validated experimentally in another GH5 endoglucanase, Cel5 from Aspergillus niger (AnCel5), which demonstrated a similar increase in thermostability. Based on molecular dynamics (MD) simulations of both the SoCel5 and TeEgl5A parent enzymes and their hybrids, we hypothesize that improved hydrophobic packing of the interface between α2 and α3 is the primary mechanism by which the hybrid enzymes increase their thermostability relative to that of the mesophilic parent SoCel5. IMPORTANCE Thermal stability is an essential property of enzymes in many industrial biotechnological applications, as high temperatures improve bioreactor throughput. Many protein engineering approaches, such as rational design and directed evolution, have been employed to improve the thermal properties of mesophilic enzymes. Structure-based recombination has also been used to fuse TIM barrel fragments, and even fragments from unrelated folds, to generate new structures. However, little research has been done on GH5 endoglucanases. In this study, two GH5 endoglucanases exhibiting TIM barrel structure, SoCel5 and TeEgl5A, with different thermal properties, were hybridized to study the roles of different (βα) motifs. This work illustrates the role that structure-guided recombination can play in helping to identify sequence function relationships within GH5 enzymes by supplementing natural diversity with synthetic diversity.

scholarly journals Rational design of a highly efficient catalytic system for the production of 3′-phosphoadenosine-5′-phosphosulfate from ATP

2021 ◽  
Author(s):  
Kaifang Liu ◽  
Xiulai Chen ◽  
Yunlu Zhong ◽  
Jia Liu ◽  
Guipeng Hu ◽  
...  
Keyword(s):  
Catalytic System ◽  
Rational Design ◽  
Specific Activity ◽  
Catalytic Efficiency ◽  
Disodium Salt ◽  
In Vivo Testing ◽  
Dynamics Simulations ◽  
Rate Limiting

The compound 3′-phosphoadenosine-5′-phosphosulfate (PAPS) serves as a sulfate group donor in the production of valuable sulfated compounds, such as glycosaminoglycan and oxamniquine. However, elevated costs and low conversion efficiency limit the industrial applicability of PAPS. Here, we designed and constructed an efficient and controllable catalytic system for the conversion of ATP (disodium salt) into PAPS without inhibition from by-products. In vitro and in vivo testing in Escherichia coli identified adenosine-5′-phosphosulfate kinase from Penicillium chrysogenum (PcAPSK) as the rate-limiting enzyme. Based on analysis of the catalytic steps and molecular dynamics simulations, a mechanism-guided “ADP expulsion” strategy was developed to generate an improved PcAPSK variant (L7), with a specific activity of 48.94 U·mg-1 and 73.27-fold higher catalytic efficiency (kcat/Km) that of the wild-type enzyme. The improvement was attained chiefly by reducing the ADP-binding affinity of PcAPSK, as well as by changing the enzyme’s flexibility and lid structure to a more open conformation. By introducing PcAPSK L7 in an in vivo catalytic system, 73.59 mM (37.32 g·L-1) PAPS was produced from 150 mM ATP in 18.5 h using a 3-L bioreactor. The achieved titer is the highest reported to date and corresponds to a 98.13% conversion rate. The proposed strategy will facilitate industrial production of PAPS as well as the engineering of similar enzymes.

Improved catalytic activity and stability of cellobiohydrolase (Cel6A) from the Aspergillus fumigatus by rational design

2020 ◽  
Vol 33 ◽  
Author(s):  
Subba Reddy Dodda ◽  
Nibedita Sarkar ◽  
Piyush Jain ◽  
Kaustav Aikat ◽  
Sudit S Mukhopadhyay
Keyword(s):  
Catalytic Activity ◽  
Protein Engineering ◽  
Aspergillus Fumigatus ◽  
Rational Design ◽  
Catalytic Efficiency ◽  
Kinetic Studies ◽  
Substrate Affinity ◽  
Wild Type ◽  
Dynamics Simulations ◽  
Cellulose Binding

Abstract Cheap production of glucose is the current challenge for the production of cheap bioethanol. Ideal protein engineering approaches are required for improving the efficiency of the members of the cellulase, the enzyme complex involved in the saccharification process of cellulose. An attempt was made to improve the efficiency of the cellobiohydrolase (Cel6A), the important member of the cellulase isolated from Aspergillus fumigatus (AfCel6A). Structure-based variants of AfCel6A were designed. Amino acids surrounding the catalytic site and conserved residues in the cellulose-binding domain were targeted (N449V, N168G, Y50W and W24YW32Y). I mutant 3 server was used to identify the potential variants based on the free energy values (∆∆G). In silico structural analyses and molecular dynamics simulations evaluated the potentiality of the variants for increasing thermostability and catalytic activity of Cel6A. Further enzyme studies with purified protein identified the N449V is highly thermo stable (60°C) and pH tolerant (pH 5–7). Kinetic studies with Avicel determined that substrate affinity of N449V (Km =0.90 ± 0.02) is higher than the wild type (1.17 ± 0.04) and the catalytic efficiency (Kcat/Km) of N449V is ~2-fold higher than wild type. All these results suggested that our strategy for the development of recombinant enzyme is a right approach for protein engineering.

scholarly journals Disulfide Bond Engineering of an Endoglucanase from Penicillium verruculosum to Improve Its Thermostability

2019 ◽  
Vol 20 (7) ◽  
pp. 1602 ◽  
Author(s):  
Anna Bashirova ◽  
Subrata Pramanik ◽  
Pavel Volkov ◽  
Aleksandra Rozhkova ◽  
Vitaly Nemashkalov ◽  
...  
Keyword(s):  
Disulfide Bond ◽  
Rational Design ◽  
Specific Activity ◽  
Catalytic Performance ◽  
Industrial Applications ◽  
Penicillium Verruculosum ◽  
Bulk Chemicals ◽  
Commercial Applications ◽  
The Stability ◽  
Dynamics Simulations

Endoglucanases (EGLs) are important components of multienzyme cocktails used in the production of a wide variety of fine and bulk chemicals from lignocellulosic feedstocks. However, a low thermostability and the loss of catalytic performance of EGLs at industrially required temperatures limit their commercial applications. A structure-based disulfide bond (DSB) engineering was carried out in order to improve the thermostability of EGLII from Penicillium verruculosum. Based on in silico prediction, two improved enzyme variants, S127C-A165C (DSB2) and Y171C-L201C (DSB3), were obtained. Both engineered enzymes displayed a 15–21% increase in specific activity against carboxymethylcellulose and β-glucan compared to the wild-type EGLII (EGLII-wt). After incubation at 70 °C for 2 h, they retained 52–58% of their activity, while EGLII-wt retained only 38% of its activity. At 80 °C, the enzyme-engineered forms retained 15–22% of their activity after 2 h, whereas EGLII-wt was completely inactivated after the same incubation time. Molecular dynamics simulations revealed that the introduced DSB rigidified a global structure of DSB2 and DSB3 variants, thus enhancing their thermostability. In conclusion, this work provides an insight into DSB protein engineering as a potential rational design strategy that might be applicable for improving the stability of other enzymes for industrial applications.

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

Purification and Characterization of Natural Solid-Substrate Degrading and Alcohol Producing Hyperthermostable Alkaline Amylase from Bacillus cereus (sm-sr14)

2020 ◽  
Vol 21 (9) ◽  
pp. 872-881
Author(s):  
Sumit Sahoo ◽  
Sudipta Roy ◽  
Dipannita Santra ◽  
Sayantani Maiti ◽  
Sonali Roul ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Main Property ◽  
Solid Substrate ◽  
Industrial Applications ◽  
Starch Degradation ◽  
Significant Similarity ◽  
Alcohol Production ◽  
Cazy Database ◽  
Tim Barrel ◽  
Alkaline Amylase

Objective: Amylases enzymes hydrolyze starch molecules to produce diverse products including dextrins, and progressively smaller polymers. These include glucose units linked through α-1- 1, α-1-4, α-1-6, glycosidic bonds. Methods: This enzyme carrying an (α /β) 8 or TIM barrel structure is also produced containing the catalytic site residues. These groups of enzymes possess four conserved regions in their primary sequence. In the Carbohydrate-Degrading Enzyme (CAZy) database, α-amylases are classified into different Glycoside Hydrolase Families (GHF) based on their amino acid sequence. The present objective was to study one such enzyme based on its molecular characterization after purification in our laboratory. Its main property of solid-natural starch degradation was extensively investigated for its pharmaceutical/ industrial applications. Results: Amylase producing bacteria Bacillus cereus sm-sr14 (Accession no. KM251578.1) was purified to homogeneity on a Seralose 6B-150 gel-matrix and gave a single peak during HPLC. MALDITOF mass-spectrometry with bioinformatics studies revealed its significant similarity to α/β hydrolase family. The enzyme showed an efficient application; favourable Km, Vmax and Kcat during the catalysis of different natural solid starch materials. Analysis for hydrolytic product showed that this enzyme can be classified as the exo-amylase asit produced a significant amount of glucose. Conclusion: Besides the purified enzyme, the present organism Bacillus cereus sm-sr14 could degrade natural solid starch materials like potato and rice up to the application level in the pharmaceutical/ industrial field for alcohol production.

scholarly journals Modeled 3D-Structures of Proteobacterial Transglycosylases from Glycoside Hydrolase Family 17 Give Insight in Ligand Interactions Explaining Differences in Transglycosylation Products

2021 ◽  
Vol 11 (9) ◽  
pp. 4048
Author(s):  
Javier A. Linares-Pastén ◽  
Lilja Björk Jonsdottir ◽  
Gudmundur O. Hreggvidsson ◽  
Olafur H. Fridjonsson ◽  
Hildegard Watzlawick ◽  
...  
Keyword(s):  
Glycoside Hydrolase ◽  
Ligand Docking ◽  
Glycoside Hydrolase Family ◽  
Ligand Interactions ◽  
Tim Barrel ◽  
Branching Point ◽  
The Difference ◽  
Dynamics Simulations ◽  
And Function ◽  
Hydrolase Family

The structures of glycoside hydrolase family 17 (GH17) catalytic modules from modular proteins in the ndvB loci in Pseudomonas aeruginosa (Glt1), P. putida (Glt3) and Bradyrhizobium diazoefficiens (previously B. japonicum) (Glt20) were modeled to shed light on reported differences between these homologous transglycosylases concerning substrate size, preferred cleavage site (from reducing end (Glt20: DP2 product) or non-reducing end (Glt1, Glt3: DP4 products)), branching (Glt20) and linkage formed (1,3-linkage in Glt1, Glt3 and 1,6-linkage in Glt20). Hybrid models were built and stability of the resulting TIM-barrel structures was supported by molecular dynamics simulations. Catalytic amino acids were identified by superimposition of GH17 structures, and function was verified by mutagenesis using Glt20 as template (i.e., E120 and E209). Ligand docking revealed six putative subsites (−4, −3, −2, −1, +1 and +2), and the conserved interacting residues suggest substrate binding in the same orientation in all three transglycosylases, despite release of the donor oligosaccharide product from either the reducing (Glt20) or non-reducing end (Glt1, Gl3). Subsites +1 and +2 are most conserved and the difference in release is likely due to changes in loop structures, leading to loss of hydrogen bonds in Glt20. Substrate docking in Glt20 indicate that presence of covalently bound donor in glycone subsites −4 to −1 creates space to accommodate acceptor oligosaccharide in alternative subsites in the catalytic cleft, promoting a branching point and formation of a 1,6-linkage. The minimum donor size of DP5, can be explained assuming preferred binding of DP4 substrates in subsite −4 to −1, preventing catalysis.

scholarly journals Specific inhibition of the Survivin–CRM1 interaction by peptide-modified molecular tweezers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Annika Meiners ◽  
Sandra Bäcker ◽  
Inesa Hadrović ◽  
Christian Heid ◽  
Christine Beuck ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Rational Design ◽  
Nuclear Export Signal ◽  
Signal Interference ◽  
Receptor Interaction ◽  
Dual Function ◽  
Experimental Proof ◽  
Molecular Tweezers ◽  
Recognition Element ◽  
Dynamics Simulations

AbstractSurvivin’s dual function as apoptosis inhibitor and regulator of cell proliferation is mediated via its interaction with the export receptor CRM1. This protein–protein interaction represents an attractive target in cancer research and therapy. Here, we report a sophisticated strategy addressing Survivin’s nuclear export signal (NES), the binding site of CRM1, with advanced supramolecular tweezers for lysine and arginine. These were covalently connected to small peptides resembling the natural, self-complementary dimer interface which largely overlaps with the NES. Several biochemical methods demonstrated sequence-selective NES recognition and interference with the critical receptor interaction. These data were strongly supported by molecular dynamics simulations and multiscale computational studies. Rational design of lysine tweezers equipped with a peptidic recognition element thus allowed to address a previously unapproachable protein surface area. As an experimental proof-of-principle for specific transport signal interference, this concept should be transferable to any protein epitope with a flanking well-accessible lysine.

scholarly journals Enhancing the thermostability and activity of uronate dehydrogenase from Agrobacterium tumefaciens LBA4404 by semi-rational engineering

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Hui-Hui Su ◽  
Fei Peng ◽  
Pei Xu ◽  
Xiao-Ling Wu ◽  
Min-Hua Zong ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Rational Design ◽  
Glucuronic Acid ◽  
Specific Activity ◽  
Value Added ◽  
Catalytic Efficiency ◽  
Site Directed Mutagenesis ◽  
Glucaric Acid ◽  
Triple Mutant ◽  
Pharmaceutical Industries

Abstract Background Glucaric acid, one of the aldaric acids, has been declared a “top value-added chemical from biomass”, and is especially important in the food and pharmaceutical industries. Biocatalytic production of glucaric acid from glucuronic acid is more environmentally friendly, efficient and economical than chemical synthesis. Uronate dehydrogenases (UDHs) are the key enzymes for the preparation of glucaric acid in this way, but the poor thermostability and low activity of UDH limit its industrial application. Therefore, improving the thermostability and activity of UDH, for example by semi-rational design, is a major research goal. Results In the present work, three UDHs were obtained from different Agrobacterium tumefaciens strains. The three UDHs have an approximate molecular weight of 32 kDa and all contain typically conserved UDH motifs. All three UDHs showed optimal activity within a pH range of 6.0–8.5 and at a temperature of 30 °C, but the UDH from A. tumefaciens (At) LBA4404 had a better catalytic efficiency than the other two UDHs (800 vs 600 and 530 s−1 mM−1). To further boost the catalytic performance of the UDH from AtLBA4404, site-directed mutagenesis based on semi-rational design was carried out. An A39P/H99Y/H234K triple mutant showed a 400-fold improvement in half-life at 59 °C, a 5 °C improvement in $$ {\text{T}}_{ 5 0}^{ 1 0} $$ T 50 10 value and a 2.5-fold improvement in specific activity at 30 °C compared to wild-type UDH. Conclusions In this study, we successfully obtained a triple mutant (A39P/H99Y/H234K) with simultaneously enhanced activity and thermostability, which provides a novel alternative for the industrial production of glucaric acid from glucuronic acid.

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