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Molecular architecture and structural transitions of a Clostridium thermocellum mini-cellulosome.
- Source :
-
Journal of molecular biology [J Mol Biol] 2011 Apr 08; Vol. 407 (4), pp. 571-80. Date of Electronic Publication: 2011 Feb 15. - Publication Year :
- 2011
-
Abstract
- The cellulosome is a highly elaborate cell-bound multienzyme complex that efficiently orchestrates the deconstruction of cellulose and hemicellulose, two of the nature's most abundant polymers. Understanding the intricacy of these nanomachines evolved by anaerobic microbes could sustain the development of an effective process for the conversion of lignocellulosic biomass to bio-ethanol. In Clostridium thermocellum, cellulosome assembly is mediated by high-affinity protein:protein interactions (>10(9) M(-1)) between dockerin modules found in the catalytic subunits and cohesin modules located in a non-catalytic protein scaffold termed CipA. Whereas the atomic structures of several cellulosomal components have been elucidated, the structural organization of the complete cellulosome remains elusive. Here, we reveal that a large fragment of the cellulosome presents a mostly compact conformation in solution, by solving the three-dimensional structure of a C. thermocellum mini-cellulosome comprising three consecutive cohesin modules, each bound to one Cel8A cellulase, at 35 Å resolution by cryo-electron microscopy. Interestingly, the three cellulosomal catalytic domains are found alternately projected outward from the CipA scaffold in opposite directions, in an arrangement that could expand the area of the substrate accessible to the catalytic domains. In addition, the cellulosome can transit from this compact conformation to a multitude of diverse and flexible structures, where the linkers between cohesin modules are extended and flexible. Thus, structural transitions controlled by changes in the degree of flexibility of linkers connecting consecutive cohesin modules could regulate the efficiency of substrate recognition and hydrolysis.<br /> (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Subjects :
- Catalytic Domain
Clostridium thermocellum chemistry
Clostridium thermocellum ultrastructure
Cryoelectron Microscopy
Models, Molecular
Protein Structure, Quaternary
Cellulase chemistry
Cellulase ultrastructure
Clostridium thermocellum enzymology
Multienzyme Complexes chemistry
Multienzyme Complexes ultrastructure
Subjects
Details
- Language :
- English
- ISSN :
- 1089-8638
- Volume :
- 407
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 21315080
- Full Text :
- https://doi.org/10.1016/j.jmb.2011.01.060