Loosenin, a novel protein with cellulose-disrupting activity from Bjerkandera adusta

Abstract

BackgroundExpansins and expansin-like proteins loosen cellulose microfibrils, possibly through the rupture of intramolecular hydrogen bonds. Together with the use of lignocellulolytic enzymes, these proteins are potential molecular tools to treat plant biomass to improve saccharification yields.ResultsHere we describe a new type of expansin-related fungal protein that we have called loosenin. Its corresponding gene, loos1, from the basidiomycete Bjerkandera adusta, was cloned and heterologously expressed in Saccharomyces cerevisiae. LOOS1 is distantly related to plant expansins through the shared presence of a DPBB domain, however domain II found in plant expansins is absent. LOOS1 binds tightly to cellulose and chitin, and we demonstrate that cotton fibers become susceptible to the action of a commercial cellulase following treatment with LOOS1. Natural fibers of Agave tequilana also become susceptible to hydrolysis by cellulases after loosenin treatment.ConclusionsLOOS1 is a new type of protein with disrupting activity on cellulose. LOOS1 binds polysaccharides, and given its enhancing properties on the action of hydrolytic enzymes, LOOS1 represents a potential additive in the production of fermentable sugars from lignocellulose.

Cerato-platanin shows expansin-like activity on cellulosic materials

“…Cotton fibres were firstly mercerized and the effect of CP was observed after sonication, in accordance to other similar works carried out with expansin-like proteins (Quiroz-Castañeda et al 2011;Saloheimo et al 2002).…”

“…to increase the efficiency of bioconversion of lignocellulose to ethanol (Arantes and Saddler 2010;Jäger et al 2011). These objectives are supported by a number of experimental data concerning the synergism with cellulases (Chen et al 2010;Kim et al 2009;Lee et al 2010;Quiroz-Castañeda et al 2011;Wang et al 2010Wang et al , 2011Zhou et al 2011). However, the biological role of expansin-type protein domains from microbes seems that of facilitating the interaction with plants, as colonization or symbiosis establishment (Brotman et al 2008;Dermatsev et al 2010;Kerff et al 2008).…”

“…The effect was quantified in about 95 broken/defibrated fibres per 100 fibres analysed after incubation with CP, and about 1 or 10 damaged fibres per 100 fibres analysed after incubation with buffer or BSA, respectively. No swollen areas or enlarged "bubbles", as described by Saloheimo et al (2002) and Quiroz-Castañeda et al (2011), were observed on CP-treated fibres.…”

“…However, expansin-like proteins have also been found in fungi and bacteria (often called swollenins or loosenins) (Bouzarelou et al 2008;Brotman et al 2008;Chen et al 2010;Dermatsev et al 2010;Kerff et al 2008;Lee et al 2010;Quiroz-Castañeda et al 2011;Saloheimo et al 2002;Yao et al 2008).…”

The Use of Carbohydrate Binding Modules (CBMs) to Monitor Changes in Fragmentation and Cellulose Fiber Surface Morphology during Cellulase- and Swollenin-induced Deconstruction of Lignocellulosic Substrates

“…These disruptive proteins include examples from plants (Expansins) (13), bacteria (Expansin-like proteins (14,15) and some carbohydrate binding modules (CBMs) 2 (16)), and fungi * This work was supported by the Natural Sciences and Engineering Council (Swollenin (8,9,12), Loosenin (17), and CBMs (18)). These proteins have also been shown to promote a variety of disruptive effects on cellulosic biomass, including filter paper dispersion, crystallinity reduction, particle size reduction, swelling of cotton fibers, and roughening of cotton fiber surface (7).…”