Supramolecular presentation– Cellulose and the cellusome

disturbedtonganeseBiotechnology

Oct 2, 2013 (3 years and 6 months ago)

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A self
-
assembling evolutionary marvel

by: Drew Sowersby


Supramolecular Chemistry 5390

Dr. Wendi David

Cellulose is the most abundant source of
bioenergy on earth

Rubin, E.
Nature
,
2008
,
454
, 841
-
845.

BIOFUELS

Applications

Singh, S.; Simmons, B. a; Vogel, K. P.
Biotechnology and bioengineering
.
2009
,
104
, 68
-
75
.

The break down of cellulose

involves 2 major steps

Pretreatment



mechanical (shear)



chemical (ionic, dilute acids)



thermochemical (heat)

Hydrolysis



enzymatic (
cellulases
)



chemical (strong acids)


switchgrass


before and after ionic liquid pretreatment

Graphic: Wikipedia

Hydrolysis to glucose is

achieved via 3 enzymatic steps

ht
tp://www.wzw.tum.de/mbiotec/celostruct.htm

The Cellulosome Concept



Bayer and Lamed (1983)



Clostridium
thermocellum

most studied



extracellular molecular machine



molecular weight of over 2
MDa

(2,000,000
Da
)


Lamed, R. et al.
Biotechnol
.
Bioeng
.
Symp
.,
1983
,
13
, 163

18.

Characterization of the cellulosome





Complex crystallization

Isothermal
calorimetry


Protein purification

Recombinant DNA technology

Bioinformatics and modeling

Electron microscopy

Surface
plasmon

resonance

Binding

Structure

Composition

What does the research say

about the cellulosome?

1.
Shoham, Y.; Lamed, R.; Bayer, E.A.
Trends Microbiol.,
1999
,
7
, 275
-
281.

2.
Schwarz, W. H.
Appl. Microbiol. Biotechnol.
2001
,
56
, 634

649.

3.
Pagès
, S.
et al
.
Proteins
,
1997
,

29
, 517

527.

4.
Carvahlo
, A. L
. et al. PNAS
,
2003
,
100
, 13809

13814.

Mechanism


Cellulosome self
-
assembly driven by
non
-
specific


but highly
complementary

cohesin/dockerin interactions



Features

o

contains18 different dockerin containing enzymes



cellulases ranging in molecular weights of 40
-
180
kDa



dockerin is a 23
-
residue tandemly repeated sequence



dockerin contains 2 calcium binding loop
-
helix motifs

o

cooperative binding by carbohydrate binding modules (CBMs)

o

binding between dockerin and cohesin is
species specific

o

cohesin is a 9
-
stranded
β

-

sandwich with a jellyroll topology

o

Scaffoldin
-
cellulase

superstructure results in synergistic
cellulolytic


activity not seen with free floating cellulases




Scaffoldin and the

dockerin
-
cohesin complex

scaffoldin

Polycellulosomal superstructures



extracellular construction



organismal

monstrosity



resting vs. protracted



“Plasticity theory”

1. Shoham, Y.; Lamed, R.; Bayer, E.A.
Trends Microbiol.,
1999
,

7
, 275
-
281.

2. Bomble, Y. J. et al.
J. Biol. Chem.,
2011
,
286
, 5614
-
5623.

Video Simulation wrap
-
up

Bomble, Y. J. et al.
J. Biol. Chem.,
2011
,
286
, 5614
-
5623.