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| Structural Insights into the Mechanism of Formation of Cellulosomes probed by SAXS | |
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Cellulosomes are large (0.7-2 MDa) multi-protein complexes that
efficiently degrade crystalline cellulose and related plant cell
wall polysaccharides. The main paradox regarding the cellulosomes
resides in their drastic enhanced catalytic efficiency, since the
individually cellulosomal cellulases display very low specific
activity. To explore this synergy the synthetic cellulosomes
(nanosomes) were produced in which selected enzymes (Cel48F,
Celcaa) were incorporated into the complexes with one or two
cohesin from Clostridium thermocellum and Clostridium
cellulolyticum by means of high-affinity species-specific
cohesin-dockerin interactions. Combining Small angle scattering
with known atomic structures of the isolated modules was used to
investigate the mechanisms of formation of these complexes by
analyzing its solution structure. The three-dimensional
rearrangement of the domains in the cellulosomal enzymes in the
free and complexed states was investigated according to the low
resolution models restored from SAXS data. The dynamical
properties of these enzymes were explored, using the normal mode
analysis. The physiological implications of these outcomes for
the mechanisms of cellulosome formation are then discussed.
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