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Tài liệu Báo cáo khoa học: The cellulosomes from Clostridium cellulolyticum Identification of new
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Tài liệu Báo cáo khoa học: The cellulosomes from Clostridium cellulolyticum Identification of new

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Mô tả chi tiết

The cellulosomes from Clostridium cellulolyticum

Identification of new components and synergies between complexes

Imen Fendri1

, Chantal Tardif1,2, Henri-Pierre Fierobe1

, Sabrina Lignon3

, Odile Valette1

, Sandrine

Page` s1,2 and Ste´phanie Perret1,2

1 Laboratoire de Chimie Bacte´rienne, CNRS, UPR9043, IMM, Marseille, France

2 Universite´ Aix Marseille, France

3 Centre de microse´quencage et d’analyse prote´omique, IMM, Marseille, France

Biomass from plant cell walls contains large quantities

of structural polysaccharides. Cellulose, the most

abundant polysaccharide, is a linear glucose polymer

forming fibrils with a regular crystalline arrangement

[1–3]. In plant cell walls, cellulose fibrils are sur￾rounded by a complex matrix of polysaccharides such

as hemicellulose and pectin [4], which make plant

cellulose resistant to enzymatic hydrolysis. Some

microorganisms secrete diverse cellulases, hemicellu￾lases (xylanases, mannanases, etc.) and pectinases that

have various and complementary modes of action

(endo, exo and processive) [5]. These plant cell-wall￾degrading enzymes, which include glycoside hydrolases

(GH), polysaccharide lyases and carbohydrate ester￾ases, have been classified into families based on their

sequence homologies (Carbohydrate Active Enzyme

Database; http://www.cazy.org) [6]. In cellulose-rich

anaerobic biotopes, bacteria such as Ruminococ￾cus flavefaciens [7,8], Bacteroides cellulosolvens [9],

Clostridium cellulolyticum [10], Clostridium thermocel￾lum [11], Clostridium cellulovorans [12] and Clostrid￾ium papyrosolvens [13] secrete multienzyme complexes

called cellulosomes which degrade plant cell walls effi￾ciently. In general, cellulosomes are composed of a

scaffolding protein devoid of enzymatic activity which

binds the complexes to the substrate via its carbo￾hydrate-binding module (CBM). This protein contains

several cohesin modules that serve as anchoring points

Keywords

cellulosome; Clostridium cellulolyticum;

diversity; new components; synergy

Correspondence

S. Perret, Laboratoire de Chimie

Bacte´rienne, CNRS, UPR9043, 31 chemin

Joseph Aiguier 13009, Marseille, France

Fax: +33 4 91 71 33 21

Tel: +33 4 91 16 43 40

E-mail: perret@ifr88.cnrs-mrs.fr

(Received 18 January 2009, revised 24

March 2009, accepted 27 March 2009)

doi:10.1111/j.1742-4658.2009.07025.x

Cellulosomes produced by Clostridium cellulolyticum grown on cellulose

were purified and separated using anion-exchange chromatography.

SDS ⁄ PAGE analysis of six fractions showed variations in their celluloso￾mal protein composition. Hydrolytic activity on carboxymethyl cellulose,

xylan, crystalline cellulose and hatched straw differed from one fraction to

another. Fraction F1 showed a high level of activity on xylan, whereas

fractions F5 and F6 were most active on crystalline cellulose and carb￾oxymethyl cellulose, respectively. Several cellulosomal components specific

to fractions F1, F5 and F6 were investigated using MS analysis. Several

hemicellulases were identified, including three xylanases in F1, and several

cellulases belonging to glycoside hydrolase families 9 and 5 and, a cystein

protease inhibitor were identified in F5 and F6. Synergies were observed

when two or three fractions were combined. A mixture containing fractions

F1, F3 and F6 showed the most divergent cellulosomal composition, the

most synergistic effects and the highest level of activity on straw (the most

heterogeneous substrate tested). These findings show that on complex sub￾strates such as straw, synergies occur between differently composed cellulo￾somes and the degradation efficiency of the cellulosomes is correlated with

their enzyme diversity.

Abbreviations

CBM, carbohydrate-binding module; CipC, cellulosome-integrating protein C; CMC, carboxymethyl cellulose; GH, glycoside hydrolases.

3076 FEBS Journal 276 (2009) 3076–3086 ª 2009 The Authors Journal compilation ª 2009 FEBS

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