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Chapter 6
than 7 days, so there is a possibility the biofilms would have matured further, but this would
not have affected the overall results.
It would have been interesting to further analyse the properties of these chaperonins. One
possibility would have been to make apical domain swaps between the Cpn60.1 and Cpn60.2
chaperonins of M. smegmatis to test the hypothesis that the apical domain is responsible for
substrate specificity. The resulting chimeric chaperonins would be tested in a similar manner
as the complementation tests shown above and in E. coli (chapter 3). Another possible
experiment could involve making specific mutations between the chaperonins to try and find
the regions that are responsible for biofilm maturation. Other experiments, such as testing if
MsCpn60.1 could allow M. tuberculosis ΔMtbcpn60.1 strains to cause granuloma in infected
mice would also have further expanded our understanding of the specialisation of the
Mycobacterial chaperonins.
In summary, the results obtained here support the original hypothesis and show that
MtbCpn60.1 can complement for the loss of endogenous Cpn60.1 in M. smegmatis. These
results are consistent with the phylogenetic data (Figure 1.20c), and with the hypothesis that
cpn60 duplicated in the strain that was ancestral to all known existing Mycobacteria, and that
separate functions evolved for one of the two copies that have been maintained subsequently
(Hughes, 1993, Hu et al., 2008, Lewthwaite et al., 2001).
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