Major characteristics of the cellulolytic system of Clostridium thermocellum coincide with those of the purified cellulosome

Lamed, Raphael; Kenig, Rina; Setter, Eva; Bayer, Edward A.

doi:10.1016/0141-0229(85)90008-0

Cited by 163 publications

(128 citation statements)

References 12 publications

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“…The overall cellulase activity is higher when cells are grown on cellulose than when they are grown on cellobiose (21,177,340,352). Although total endoglucanase activity in C. thermocellum is constitutive and not subject to carbon source repression (93,115,304), transcription of endoglucanase genes celA, celD, and celF appears to be controlled temporally (227).…”

Section: Carbon Source Regulationmentioning

confidence: 99%

Cellulase, Clostridia, and Ethanol

Demain

Newcomb

2005

Microbiol Mol Biol Rev

806

579

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SUMMARY Biomass conversion to ethanol as a liquid fuel by the thermophilic and anaerobic clostridia offers a potential partial solution to the problem of the world's dependence on petroleum for energy. Coculture of a cellulolytic strain and a saccharolytic strain of Clostridium on agricultural resources, as well as on urban and industrial cellulosic wastes, is a promising approach to an alternate energy source from an economic viewpoint. This review discusses the need for such a process, the cellulases of clostridia, their presence in extracellular complexes or organelles (the cellulosomes), the binding of the cellulosomes to cellulose and to the cell surface, cellulase genetics, regulation of their synthesis, cocultures, ethanol tolerance, and metabolic pathway engineering for maximizing ethanol yield.

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Section: Carbon Source Regulationmentioning

confidence: 99%

Cellulase, Clostridia, and Ethanol

Demain

Newcomb

2005

Microbiol Mol Biol Rev

806

579

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“…Clostridium thermocellum is a particularly efficient cellulolytic bacterium which occurs in anaerobic thermophilic ecosystems. Its cellulase activity is carried out predominantly by a multi-functional, multi-enzyme complex, termed the cellulosome (Lamed, Setter, Kenig & Bayer, 1983;Lamed & Bayer, 1988). In order to form this very large complex, the bacterium produces a special multipledomain polypeptide, called scaffoldin, which organizes the catalytic (enzymatic) subunits into the complex (Bayer, Setter & Lamed, 1985;Bayer, Morag & Lamed, 1994;Wu, OrmeJohnson & Demain, 1988;Gerngross, Romaniec, Kobayashi, Huskisson & Demain, 1993).…”

Section: Introductionmentioning

confidence: 99%

Crystallization and preliminary X-ray analysis of a cohesin domain of the cellulosome from Clostridium thermocellum

Shimon

Frolow²,

Yaron³

et al. 1997

Acta Cryst D

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Recombinant cohesin-2, a unique type of protein-recognition domain from the cellulosome of Clostridium thermocellum, has been crystallized by the hanging-drop vapor-diffusion method. The crystals are monoclinic, space group C2 with unit-cell dimensions a = 79.91, b = 47.86, c = 51.13A, fl = 126.77. There is most likely to be one molecule per asymmetric unit, corresponding to a packing density of 2.16,~ 3 Da 1 The crystals diffract to beyond 2.3 A on a conventional laboratory rotating-anode source.

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“…The plant cell wall degrading apparatus of aerobic and anaerobic microorganisms, however, differ considerably in their macromolecular organization. The plant cell wall hydrolases synthesized by anaerobes frequently assemble into a large (molecular mass Ͼ3 MDa) multienzyme complex termed the ''cellulosome'' (6,7).…”

mentioning

confidence: 99%

Evidence for a dual binding mode of dockerin modules to cohesins

Carvalho

Dias²,

Nagy

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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126

204

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The assembly of proteins that display complementary activities into macromolecular complexes is critical to cellular function. One such enzyme complex, of environmental significance, is the plant cell wall degrading apparatus of anaerobic bacteria, termed the cellulosome. The complex assembles through the interaction of enzyme-derived ''type I dockerin'' modules with the multiple ''cohesin'' modules of the scaffolding protein. Clostridium thermocellum type I dockerin modules contain a duplicated 22-residue sequence that comprises helix-1 and helix-3, respectively. The crystal structure of a C. thermocellum type I cohesin-dockerin complex showed that cohesin recognition was predominantly through helix-3 of the dockerin. The sequence duplication is reflected in near-perfect 2-fold structural symmetry, suggesting that both repeats could interact with cohesins by a common mechanism in wild-type (WT) proteins. Here, a helix-3 disrupted mutant dockerin is used to visualize the reverse binding in which the dockerin mutant is indeed rotated 180 o relative to the WT dockerin such that helix-1 now dominates recognition of its protein partner. The dual binding mode is predicted to impart significant plasticity into the orientation of the catalytic subunits within this supramolecular assembly, which reflects the challenges presented by the degradation of a heterogeneous, recalcitrant, insoluble substrate by a tethered macromolecular complex.cellulosome structure ͉ cellulosome assembly ͉ Clostridium thermocellum ͉ cohesin-dockerin

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Major characteristics of the cellulolytic system of Clostridium thermocellum coincide with those of the purified cellulosome

Cited by 163 publications

References 12 publications

Cellulase, Clostridia, and Ethanol

Cellulase, Clostridia, and Ethanol

Crystallization and preliminary X-ray analysis of a cohesin domain of the cellulosome from Clostridium thermocellum

Evidence for a dual binding mode of dockerin modules to cohesins

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