polysaccharide monooxygenases
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2022 ◽  
Vol 345 ◽  
pp. 126491
Author(s):  
Anthi Karnaouri ◽  
Koar Chorozian ◽  
Dimitrios Zouraris ◽  
Antonis Karantonis ◽  
Evangelos Topakas ◽  
...  

Author(s):  
Xiaoli Zhou ◽  
Zhiqiang Xu ◽  
Yueqiu Li ◽  
Jia He ◽  
Honghui Zhu

Lytic polysaccharide monooxygenases (LPMOs) oxidatively break down the glycosidic bonds of crystalline polysaccharides, significantly improving the saccharification efficiency of recalcitrant biomass, and have broad application prospects in industry. To meet the needs of industrial applications, enzyme engineering is needed to improve the catalytic performance of LPMOs such as enzyme activity and stability. In this study, we engineered the chitin-active CjLPMO10A from Cellvibrio japonicus through a rational disulfide bonds design. Compared with the wild-type, the variant M1 (N78C/H116C) exhibited a 3-fold increase in half-life at 60°C, a 3.5°C higher T5015, and a 7°C rise in the apparent Tm. Furthermore, the resistance of M1 to chemical denaturation was significantly improved. Most importantly, the introduction of the disulfide bond improved the thermal and chemical stability of the enzyme without causing damage to catalytic activity, and M1 showed 1.5 times the specific activity of the wild-type. Our study shows that the stability and activity of LPMOs could be improved simultaneously by selecting suitable engineering sites reasonably, thereby improving the industrial adaptability of the enzymes, which is of great significance for applications.


2022 ◽  
Vol 9 ◽  
Author(s):  
Hamid Rouina ◽  
Yu-Heng Tseng ◽  
Karaba N. Nataraja ◽  
Ramanan Uma Shaanker ◽  
Thomas Krüger ◽  
...  

Numerous Trichoderma strains are beneficial for plants, promote their growth, and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes the growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host without growth promotion. To understand the dynamics of plant-fungus interaction, we examined the secretome from both sides and revealed a substantial change under different salt regimes, and during co-cultivation. Stress-related proteins, such as a fungal cysteine-rich Kp4 domain-containing protein which inhibits plant cell growth, fungal WSC- and CFEM-domain-containing proteins, the plant calreticulin, and cell-wall modifying enzymes, disappear when the two symbionts are co-cultured under high salt concentrations. In contrast, the number of lytic polysaccharide monooxygenases increases, which indicates that the fungus degrades more plant lignocellulose under salt stress and its lifestyle becomes more saprophytic. Several plant proteins involved in plant and fungal cell wall modifications and root colonization are only found in the co-cultures under salt stress, while the number of plant antioxidant proteins decreased. We identified symbiosis- and salt concentration-specific proteins for both partners. The Arabidopsis PYK10 and a fungal prenylcysteine lyase are only found in the co-culture which promoted plant growth. The comparative analysis of the secretomes supports antioxidant enzyme assays and suggests that both partners profit from the interaction under salt stress but have to invest more in balancing the symbiosis. We discuss the role of the identified stage- and symbiosis-specific fungal and plant proteins for salt stress, and conditions promoting root colonization and plant growth.


2021 ◽  
Author(s):  
Theruvothu Madathil Vandhana ◽  
Jean‐Lou Reyre ◽  
Dangudubiyyam Sushmaa ◽  
Jean‐Guy Berrin ◽  
Bastien Bissaro ◽  
...  

Biomolecules ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1890
Author(s):  
Radina Tokin ◽  
Johan Ørskov Ipsen ◽  
Mahesha M. Poojary ◽  
Poul Erik Jensen ◽  
Lisbeth Olsson ◽  
...  

Fermented persimmon juice, Kakishibu, has traditionally been used for wood and paper protection. This protective effect stems at least partially from inhibition of microbial cellulose degrading enzymes. The inhibitory effect of Kakishibu on lytic polysaccharide monooxygenases (LPMOs) and on a cocktail of cellulose hydrolases was studied, using three different cellulosic substrates. Dose dependent inhibition of LPMO activity by a commercial Kakishibu product was assessed for the well-characterized LPMO from Thermoascus aurantiacus TaAA9A, and the inhibitory effect was confirmed on five additional microbial LPMOs. The model tannin compound, tannic acid exhibited a similar inhibitory effect on TaAA9A as Kakishibu. It was further shown that both polyethylene glycol and tannase can alleviate the inhibitory effect of Kakishibu and tannic acid, indicating a likely mechanism of inhibition caused by unspecific tannin–protein interactions.


2021 ◽  
Author(s):  
Gabriela C. Schröder ◽  
William B. O'Dell ◽  
Simon P. Webb ◽  
Pratul K. Agarwal ◽  
Flora Meilleur

Metalloproteins perform a diverse array of redox-related reactions facilitated by the increased chemical functionality afforded by their metallocofactors. Lytic polysaccharide monooxygenases (LPMOs) are a class of copper-dependent enzymes that are responsible for the breakdown of recalcitrant polysaccharides via oxidative cleavage at the glycosidic bond. The activated copper-oxygen intermediates and their mechanism of formation remains to be established. Neutron protein crystallography which permits direct visualization of protonation states was used to investigate the initial steps of oxygen activation directly following active site copper reduction in Neurospora crassa LPMO9D. Herein, we cryo-trap an activated dioxygen intermediate in a mixture of superoxo and hydroperoxo states, and we identify the conserved second coordination shell residue His157 as the proton donor. Density functional theory (DFT) calculations indicate that both active site states are stable. The hydroperoxo formed is potentially an intermediate in the mechanism of hydrogen peroxide formation in the absence of substrate. We establish that the N-terminal amino group of the copper coordinating His1 remains doubly protonated directly following molecular oxygen reduction by copper. Aided by mining minima free energy calculations we establish His157 conformational flexibility in solution that is abolished by steric hindrance in the crystal. A neutron crystal structure of NcLPMO9D at low pH supports occlusion of the active site which prevents protonation of His157 at acidic conditions.


ChemSusChem ◽  
2021 ◽  
Author(s):  
Peicheng Sun ◽  
Christophe V. F. P. Laurent ◽  
Vincent J. P. Boerkamp ◽  
Gijs van Erven ◽  
Roland Ludwig ◽  
...  

2021 ◽  
pp. 110939
Author(s):  
Carolina Buruaga-Ramiro ◽  
Noelia Fernández-Gándara ◽  
L. Verónica Cabañas-Romero ◽  
Susana V. Valenzuela ◽  
F.I. Javier Pastor ◽  
...  

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