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Wilfrid Laurier University Faculty of Science
April 27, 2015
Canadian Excellence

Joel Weadge


email: Joel Weadge
phone: 519-884-0710
ext: 2161


Schematic of the cellulose biosynthetic system.


  Structure-Function Characterization of Proteins Involved in 
  Cellulose Biosynthesis by Escherichia coli and Salmonella spp.

The World Health Organization reports that diarrheal diseases are 
responsible for 2.16 million deaths annually making them among
the top five leading causes of death in the world. Members of the
Enterobacteriaceae account for many of these deaths, as they are
some of the most common and widely distributed pathogens. A
first line of defense for these bacteria are extracellular matrices
composed predominantly of exopolysaccharide. The purpose of
these polysaccharides can vary widely depending on their
location and composition. For example, a highly resistant biofilm,
composed of cellulose and curli fimbriae, promotes the adherence
of pathogenic E. coli (EPEC, EHEC, UPEC) and Salmonella
species (S. enterica serovar Typhimurium and S. enterica serovar
Enteritidis) to biotic and abiotic surfaces. The biofilm matrix also
helps the encased bacterial cells elude detection by the immune
system and provides protection from antimicrobial agents or harsh
environmental factors. Bacterial cellulose is also gaining industrial significance as it has unique physical/chemical
properties that provide significant advantages when compared to algal or plant derived cellulose. These properties have
been successfully exploited for the generation of novel wound dressings, bio-plastics, biofuels and even bio-inert
supports for tissue regeneration. Even though the medical and industrial implications of bacterial cellulose are
expanding, little is known about the synthesis and export of this polymer by bacteria.
Genetic mutational studies have demonstrated that the proteins required for the biosynthesis of cellulose in Salmonella
and Escherichia species are encoded on two neighbouring regions of the chromosome, the bcsABZC and bcsEFG
operons. BcsA and BcsB are proposed to comprise the cellulose synthase subunit that catalyzes the formation of
bacterial cellulose. BcsZ is a cellulase that cleaves intrastrand ß-1,4 linkages in the cellulose chain and is proposed to
have a role in the release of the growing polymer from the cell. The remaining proteins (BcsC/BcsE/BcsF/BcsG) are
predicted to be involved in the export of the polymer across the bacterial cell wall by forming a complex that is
analogous to the alginate and ß-1,6-poly-N-acetyl-D-glucosamine export systems. Our understanding of this group of
export systems is still in its infancy, but it is clear that they are distinct from the well-characterized capsule and
lipopolysaccharide systems. My research program will utilize a combination of state-of-the-art approaches, such as enzymology, mass spectrometry, X-ray crystallography, and nuclear magnetic resonance spectroscopy to characterize each of the proteins involved in the biosynthesis, export and degradation of cellulose. The results of this research will be key to revealing unique
approaches to circumvent the biofilm barrier and may lead to avenues for designing biopolymers with specific traits for medical and industrial applications.




Interesting Comments:

"Cellulose has been labelled as the most abundant polymer on earth." 

"Diarrheal diseases are responsible for 2.16 million deaths annually, making them one of the top five leading

causes of death in the world." - World Health Organization, 2008                                                                                              

                                                                                                                                                                                                                                                                                                                                                                                      The Weadge Lab: 

To see current lab members and possible research opportunities click here.