scholarly journals An intron-containing glycoside hydrolase family 9 cellulase gene encodes the dominant 90 kDa component of the cellulosome of the anaerobic fungus Piromyces sp. strain E2

2002 ◽  
Vol 365 (1) ◽  
pp. 193-204 ◽  
Author(s):  
Peter J.M. STEENBAKKERS ◽  
Wimal UBHAYASEKERA ◽  
Harry J.A.M. GOOSSEN ◽  
Erik M.H.M. van LIEROP ◽  
Chris van der DRIFT ◽  
...  

The cellulosome produced by Piromyces sp. strain E2 during growth on filter paper was purified by using an optimized cellulose-affinity method consisting of steps of EDTA washing of the cellulose-bound protein followed by elution with water. Three dominant proteins were identified in the cellulosome preparation, with molecular masses of 55, 80 and 90kDa. Treatment of cellulose-bound cellulosome with a number of denaturing agents was also tested. Incubation with 0.5% (w/v) SDS or 8M urea released most cellulosomal proteins, while leaving the greater fraction of the 80, 90 and 170kDa components. To investigate the major 90kDa cellulosome protein further, the corresponding gene, cel9A, was isolated, using immunoscreening and N-terminal sequencing. Inspection of the cel9A genomic organization revealed the presence of four introns, allowing the construction of a consensus for introns in anaerobic fungi. The 2800bp cDNA clone contained an open reading frame of 2334bp encoding a 757-residue extracellular protein. Cel9A includes a 445-residue glycoside hydrolase family 9 catalytic domain, and so is the first fungal representative of this large family. Both modelling of the catalytic domain as well as the activity measured with low level expression in Escherichia coli indicated that Cel9A is an endoglucanase. The catalytic domain is succeeded by a putative β-sheet module of 160 amino acids with unknown function, followed by a threonine-rich linker and three fungal docking domains. Homology modelling of the Cel9A dockerins suggested that the cysteine residues present are all involved in disulphide bridges. The results presented here are used to discuss evolution of glycoside hydrolase family 9 enzymes.

2000 ◽  
Vol 346 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Noriki MATSUO ◽  
Satoshi KANEKO ◽  
Atsushi KUNO ◽  
Hideyuki KOBAYASHI ◽  
Isao KUSAKABE

α-L-Arabinofuranosidases I and II were purified from the culture filtrate of Streptomyces chartreusis GS901 and were found to have molecular masses of 80 and 37 kDa and pI values of 6.6 and 7.5 respectively. Both enzymes demonstrated slight reactivity towards arabinoxylan and arabinogalactan as substrates but did not hydrolyse gum arabic or arabinoxylo-oligosaccharides. α-L-Arabinofuranosidase I hydrolysed all of the α-linkage types that normally occur between two α-L-arabinofuranosyl residues, with the following decreasing order of reactivity being observed for the respective disaccharide linkages: α-(1 → 2) α-(1 → 3) α-(1 → 5). This enzyme cleaved the (1 → 3) linkages of the arabinosyl side-chains of methyl 3,5-di-O-α-L-arabinofuranosyl-α-L-arabinofuranoside in preference to the (1 → 5) linkages. α-L-Arabinofuranosidase I hydrolysed approx. 30% of the arabinan but hydrolysed hardly any linear arabinan. In contrast, α-L-Arabinofuranosidase II hydrolysed only (1 → 5)-arabinofuranobioside among the regioisomeric methyl arabinobiosides and did not hydrolyse the arabinotrioside. Linear 1 → 5-linked arabinan was a good substrate for this enzyme, but it hydrolysed hardly any of the arabinan. Synergism between the two enzymes was observed in the conversion of arabinan and debranched arabinan into arabinose. Complete amino acid sequencing of α-L-arabinofuranosidase I indicated that the enzyme consists of a central catalytic domain that belongs to family 51 of the glycoside hydrolases and additionally that unknown functional domains exist in the N-terminal and C-terminal regions. The amino acid sequence of α-L-arabinofuranosidase II indicated that this enzyme belongs to family 43 of the glycoside hydrolase family and, as this is the first report of an exo-1,5-α-L-arabinofuranosidase, it represents a novel type of enzyme.


2018 ◽  
Vol 37 (5) ◽  
pp. 454-460
Author(s):  
Carola Schröder ◽  
Christin Burkhardt ◽  
Philip Busch ◽  
Georg Schirrmacher ◽  
Jörg Claren ◽  
...  

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.


2016 ◽  
Vol 473 (4) ◽  
pp. 463-472 ◽  
Author(s):  
Yuji Honda ◽  
Sachiko Arai ◽  
Kentaro Suzuki ◽  
Motomitsu Kitaoka ◽  
Shinya Fushinobu

The crystal structure of an inverting exo-β-D-glucosaminidase from glycoside hydrolase family 9 was determined. This is the first description of the structure of an exo-type enzyme from this family. A glycosynthase was produced from this enzyme through saturation mutagenesis.


2017 ◽  
Vol 101 (14) ◽  
pp. 5723-5737 ◽  
Author(s):  
Cheng-Jie Duan ◽  
Ming-Yue Huang ◽  
Hao Pang ◽  
Jing Zhao ◽  
Chao-Xing Wu ◽  
...  

2002 ◽  
Vol 184 (15) ◽  
pp. 4124-4133 ◽  
Author(s):  
Kaveh Emami ◽  
Tibor Nagy ◽  
Carlos M. G. A. Fontes ◽  
Luis M. A. Ferreira ◽  
Harry J. Gilbert

ABSTRACT Pseudomonas cellulosa is a highly efficient xylan-degrading bacterium. Genes encoding five xylanases, and several accessory enzymes, which remove the various side chains that decorate the xylan backbone, have been isolated from the pseudomonad and characterized. The xylanase genes consist of xyn10A, xyn10B, xyn10C, xyn10D, and xyn11A, which encode Xyn10A, Xyn10B, Xyn10C, Xyn10D, and Xyn11A, respectively. In this study a sixth xylanase gene, xyn11B, was isolated which encodes a 357-residue modular enzyme, designated Xyn11B, comprising a glycoside hydrolase family 11 catalytic domain appended to a C-terminal X-14 module, a homologue of which binds to xylan. Localization studies showed that the two xylanases with glycoside hydrolase family (GH) 11 catalytic modules, Xyn11A and Xyn11B, are secreted into the culture medium, whereas Xyn10C is membrane bound. xyn10C, xyn10D, xyn11A, and xyn11B were all abundantly expressed when the bacterium was cultured on xylan or β-glucan but not on medium containing mannan, whereas glucose repressed transcription of these genes. Although all of the xylanase genes were induced by the same polysaccharides, temporal regulation of xyn11A and xyn11B was apparent on xylan-containing media. Transcription of xyn11A occurred earlier than transcription of xyn11B, which is consistent with the predicted mode of action of the encoded enzymes. Xyn11A, but not Xyn11B, exhibits xylan esterase activity, and the removal of acetate side chains is required for xylanases to hydrolyze the xylan backbone. A transposon mutant of P. cellulosa in which xyn11A and xyn11B were inactive displayed greatly reduced extracellular but normal cell-associated xylanase activity, and its growth rate on medium containing xylan was indistinguishable from wild-type P. cellulosa. Based on the data presented here, we propose a model for xylan degradation by P. cellulosa in which the GH11 enzymes convert decorated xylans into substituted xylooligosaccharides, which are then hydrolyzed to their constituent sugars by the combined action of cell-associated GH10 xylanases and side chain-cleaving enzymes.


Author(s):  
Youssef Bacila Sade ◽  
Camila Silva Gonçalves ◽  
Sandra Mara Naressi Scapin ◽  
Guilherme Luiz Pinheiro ◽  
Roberto Becht Flatschart ◽  
...  

2018 ◽  
Vol 475 (9) ◽  
pp. 1533-1551 ◽  
Author(s):  
Franz J. St John ◽  
Diane Dietrich ◽  
Casey Crooks ◽  
Peter Balogun ◽  
Vesna de Serrano ◽  
...  

Glycoside hydrolase family 30 subfamily 8 (GH30-8) β-1,4-endoxylanases are known for their appendage-dependent function requiring recognition of an α-1,2-linked glucuronic acid (GlcA) common to glucuronoxylans for hydrolysis. Structural studies have indicated that the GlcA moiety of glucuronoxylans is coordinated through six hydrogen bonds and a salt bridge. These GlcA-dependent endoxylanases do not have significant activity on xylans that do not bear GlcA substitutions such as unsubstituted linear xylooligosaccharides or cereal bran arabinoxylans. In the present study, we present the structural and biochemical characteristics of xylanase 30A from Clostridium acetobutylicum (CaXyn30A) which was originally selected for study due to predicted structural differences within the GlcA coordination loops. Amino acid sequence comparisons indicated that this Gram-positive-derived GH30-8 more closely resembles Gram-negative derived forms of these endoxylanases: a hypothesis borne out in the developed crystallographic structure model of the CaXyn30A catalytic domain (CaXyn30A-CD). CaXyn30A-CD hydrolyzes xylans to linear and substituted oligoxylosides showing the greatest rate with the highly arabinofuranose (Araf)-substituted cereal arabinoxylans. CaXyn30A-CD hydrolyzes xylooligosaccharides larger than xylotriose and shows an increased relative rate of hydrolysis for xylooligosaccharides containing α-1,2-linked arabinofuranose substitutions. Biochemical analysis confirms that CaXyn30A benefits from five xylose-binding subsites which extend from the −3 subsite to the +2 subsite of the binding cleft. These studies indicate that CaXyn30A is a GlcA-independent endoxylanase that may have evolved for the preferential recognition of α-1,2-Araf substitutions on xylan chains.


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