A plasmid borne, functionally novel glycoside hydrolase family 30 subfamily 8 endoxylanase from solventogenic Clostridium
Autor: | Jason C. Hurlbert, Casey Crooks, Franz J. St John, Vesna de Serrano, Elizabeth Bales, Edwin Pozharski, James Kennon Smith, Peter Balogun, Diane M. Dietrich |
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Rok vydání: | 2018 |
Předmět: |
Models
Molecular structure–function 0301 basic medicine glycoside hydrolase family 30 Protein Conformation Stereochemistry 030106 microbiology Oligosaccharides Sequence Homology Glucuronates Crystallography X-Ray Biochemistry Substrate Specificity 03 medical and health sciences Clostridium Protein structure Catalytic Domain Glucuronoxylan Glycoside hydrolase Amino Acid Sequence protein structure Molecular Biology Peptide sequence Research Articles chemistry.chemical_classification Endo-1 4-beta Xylanases biology Chemistry Hydrolysis Cell Biology biology.organism_classification Xylan arabinoxylan 030104 developmental biology GH30 Xylanase Salt bridge Plasmids Research Article |
Zdroj: | Biochemical Journal |
ISSN: | 1470-8728 0264-6021 |
Popis: | 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. |
Databáze: | OpenAIRE |
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