100 research outputs found
Crystal structure of the feruloyl esterase from Lentilactobacillus buchneri reveals a novel homodimeric state
Ferulic acid is a common constituent of the plant cell-wall matrix where it decorates and can crosslink mainly arabinoxylans to provide structural reinforcement. Microbial feruloyl esterases (FAEs) specialize in catalyzing hydrolysis of the ester bonds between phenolic acids and sugar residues in plant cell-wall polysaccharides such as arabinoxylan to release cinnamoyl compounds. Feruloyl esterases from lactic acid bacteria (LAB) have been highlighted as interesting enzymes for their potential applications in the food and pharmaceutical industries; however, there are few studies on the activity and structure of FAEs of LAB origin. Here, we report the crystal structure and biochemical characterization of a feruloyl esterase (LbFAE) from Lentilactobacillus buchneri, a LAB strain that has been used as a silage additive. The LbFAE structure was determined in the absence and presence of product (FA) and reveals a new type of homodimer association not previously observed for fungal or bacterial FAEs. The two subunits associate to restrict access to the active site such that only single FA chains attached to arabinoxylan can be accommodated, an arrangement that excludes access to FA cross-links between arabinoxylan chains. This narrow specificity is further corroborated by the observation that no FA dimers are produced, only FA, when feruloylated arabinoxylan is used as substrate. Docking of arabinofuranosyl-ferulate in the LbFAE structure highlights the restricted active site and lends further support to our hypothesis that LbFAE is specific for single FA side chains in arabinoxylan
Cryptosporidium as a testbed for single cell genome characterization of unicellular eukaryotes
Myceliophthora thermophila M77 utilizes hydrolytic and oxidative mechanisms to deconstruct biomass
Biomass is abundant, renewable and useful for biofuel production as well as chemical priming for plastics and composites. Deconstruction of biomass by enzymes is perceived as recalcitrant while an inclusive breakdown mechanism remains to be discovered. Fungi such as Myceliophthora thermophila M77 appear to decompose natural biomass sources quite well. This work reports on this fungus fermentation property while producing cellulolytic enzymes using natural biomass substrates. Little hydrolytic activity was detected, insufficient to explain the large amount of biomass depleted in the process. Furthermore, this work makes a comprehensive account of extracellular proteins and describes how secretomes redirect their qualitative protein content based on the nature and chemistry of the nutritional source. Fungus grown on purified cellulose or on natural biomass produced secretomes constituted by: cellobiohydrolases, cellobiose dehydrogenase, B-1,3 glucanase, B-glucosidases, aldose epimerase, glyoxal oxidase, GH74 xyloglucanase, galactosidase, aldolactonase and polysaccharide monooxygenases. Fungus grown on a mixture of purified hemicellulose fractions (xylans, arabinans and arabinoxylans) produced many enzymes, some of which are listed here: xylosidase, mixed B-1,3(4) glucanase, B-1,3 glucanases, B-glucosidases, B-mannosidase, B-glucosidases, galactosidase, chitinases, polysaccharide lyase, endo B-1,6 galactanase and aldose epimerase. Secretomes produced on natural biomass displayed a comprehensive set of enzymes involved in hydrolysis and oxidation of cellulose, hemicellulose-pectin and lignin. The participation of oxidation reactions coupled to lignin decomposition in the breakdown of natural biomass may explain the discrepancy observed for cellulose decomposition in relation to natural biomass fermentation experiments.Peer reviewedMicrobiology and Molecular GeneticsBiochemistry and Microbiolog
A multifunctional thermophilic glycoside hydrolase from Caldicellulosiruptor owensensis with potential applications in production of biofuels and biochemicals
Comparative insights into the saccharification potentials of a relatively unexplored but robust Penicillium funiculosum glycoside hydrolase 7 cellobiohydrolase
A homodimeric bacterial exo beta 1,3 glucanase derived from moose rumen microbiome shows a structural framework similar to yeast exo beta 1,3 glucanases
Crystal Structure of the Polyextremophilic α-Amylase AmyB from Halothermothrix orenii: Details of a Productive Enzyme-Substrate Complex and an N Domain with a Role in Binding Raw Starch
10.1016/j.jmb.2008.02.041Journal of Molecular Biology3784850-868JMOB
- …