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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 surrounded 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, hemicellulases (xylanases, mannanases, etc.) and pectinases that
have various and complementary modes of action
(endo, exo and processive) [5]. These plant cell-walldegrading enzymes, which include glycoside hydrolases
(GH), polysaccharide lyases and carbohydrate esterases, 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 Ruminococcus flavefaciens [7,8], Bacteroides cellulosolvens [9],
Clostridium cellulolyticum [10], Clostridium thermocellum [11], Clostridium cellulovorans [12] and Clostridium papyrosolvens [13] secrete multienzyme complexes
called cellulosomes which degrade plant cell walls efficiently. In general, cellulosomes are composed of a
scaffolding protein devoid of enzymatic activity which
binds the complexes to the substrate via its carbohydrate-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 cellulosomal 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 carboxymethyl 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 substrates such as straw, synergies occur between differently composed cellulosomes 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