scholarly journals Insights into the structure and function of fungal β-mannosidases from glycoside hydrolase family 2 based on multiple crystal structures of theTrichoderma harzianumenzyme

FEBS Journal ◽  
2014 ◽  
Vol 281 (18) ◽  
pp. 4165-4178 ◽  
Author(s):  
Alessandro S. Nascimento ◽  
Joao Renato C. Muniz ◽  
Ricardo Aparício ◽  
Alexander M. Golubev ◽  
Igor Polikarpov
2013 ◽  
Vol 80 (3) ◽  
pp. 917-927 ◽  
Author(s):  
Mun Su Rhee ◽  
Lusha Wei ◽  
Neha Sawhney ◽  
John D. Rice ◽  
Franz J. St. John ◽  
...  

ABSTRACTXylans are the predominant polysaccharides in hemicelluloses and an important potential source of biofuels and chemicals. The ability ofBacillus subtilissubsp.subtilisstrain 168 to utilize xylans has been ascribed to secreted glycoside hydrolase family 11 (GH11) and GH30 endoxylanases, encoded by thexynAandxynCgenes, respectively. Both of these enzymes have been defined with respect to structure and function. In this study, the effects of deletion of thexynAandxynCgenes, individually and in combination, were evaluated for xylan utilization and formation of acidic xylooligosaccharides. Parent strain 168 depolymerizes methylglucuronoxylans (MeGXn), releasing the xylobiose and xylotriose utilized for growth and accumulating the aldouronate methylglucuronoxylotriose (MeGX3) with some methylglucuronoxylotetraose (MeGX4). The combined GH11 and GH30 activities process the products generated by their respective actions on MeGXnto release a maximal amount of neutral xylooligosaccharides for assimilation and growth, at the same time forming MeGX3in which the internal xylose is substituted with methylglucuronate (MeG). Deletion ofxynAresults in the accumulation of β-1,4-xylooligosaccharides with degrees of polymerization ranging from 4 to 18 and an average degree of substitution of 1 in 7.2, each with a single MeG linked α-1,2 to the xylose penultimate to the xylose at the reducing terminus. Deletion of thexynCgene results in the accumulation of aldouronates comprised of 4 or more xylose residues in which the MeG may be linked α-1,2 to the xylose penultimate to the nonreducing xylose. TheseB. subtilislines may be used for the production of acidic xylooligosaccharides with applications in human and veterinary medicine.


Biochemistry ◽  
2010 ◽  
Vol 49 (15) ◽  
pp. 3305-3316 ◽  
Author(s):  
Paul V. Harris ◽  
Ditte Welner ◽  
K. C. McFarland ◽  
Edward Re ◽  
Jens-Christian Navarro Poulsen ◽  
...  

2021 ◽  
Vol 11 (9) ◽  
pp. 4048
Author(s):  
Javier A. Linares-Pastén ◽  
Lilja Björk Jonsdottir ◽  
Gudmundur O. Hreggvidsson ◽  
Olafur H. Fridjonsson ◽  
Hildegard Watzlawick ◽  
...  

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.


2019 ◽  
Vol 75 (12) ◽  
pp. 1138-1147
Author(s):  
Hsiao-Chuan Huang ◽  
Liu-Hong Qi ◽  
Yo-Chia Chen ◽  
Li-Chu Tsai

The catalytic domain (residues 128–449) of the Orpinomyces sp. Y102 CelC7 enzyme (Orp CelC7) exhibits cellobiohydrolase and cellotriohydrolase activities. Crystal structures of Orp CelC7 and its cellobiose-bound complex have been solved at resolutions of 1.80 and 2.78 Å, respectively. Cellobiose occupies subsites +1 and +2 within the active site of Orp CelC7 and forms hydrogen bonds to two key residues: Asp248 and Asp409. Furthermore, its substrate-binding sites have both tunnel-like and open-cleft conformations, suggesting that the glycoside hydrolase family 6 (GH6) Orp CelC7 enzyme may perform enzymatic hydrolysis in the same way as endoglucanases and cellobiohydrolases. LC-MS/MS analysis revealed cellobiose (major) and cellotriose (minor) to be the respective products of endo and exo activity of the GH6 Orp CelC7.


2013 ◽  
Vol 452 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Kentaro Suzuki ◽  
Jun-Ichi Sumitani ◽  
Young-Woo Nam ◽  
Toru Nishimaki ◽  
Shuji Tani ◽  
...  

GH3 (glycoside hydrolase family 3) BGLs (β-glucosidases) from filamentous fungi have been widely and commercially used for the supplementation of cellulases. AaBGL1 (Aspergillus aculeatus BGL1) belongs to the GH3 and shows high activity towards cellooligosaccharides up to high degree of polymerization. In the present study we determined the crystal structure of AaBGL1. In addition to the substrate-free structure, the structures of complexes with glucose and various inhibitors were determined. The structure of AaBGL1 is highly glycosylated with 88 monosaccharides (18 N-glycan chains) in the dimer. The largest N-glycan chain comprises ten monosaccharides and is one of the largest glycans ever observed in protein crystal structures. A prominent insertion region exists in a fibronectin type III domain, and this region extends to cover a wide surface area of the enzyme. The subsite +1 of AaBGL1 is highly hydrophobic. Three aromatic residues are present at subsite +1 and are located in short loop regions that are uniquely present in this enzyme. There is a long cleft extending from subsite +1, which appears to be suitable for binding long cellooligosaccharides. The crystal structures of AaBGL1 from the present study provide an important structural basis for the technical improvement of enzymatic cellulosic biomass conversion.


2013 ◽  
Vol 288 (17) ◽  
pp. 11795-11806 ◽  
Author(s):  
Tasuku Ito ◽  
Takane Katayama ◽  
Mitchell Hattie ◽  
Haruko Sakurama ◽  
Jun Wada ◽  
...  

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