Earlier this year American scientists discovered that the repressor protein Lex A, involved in SOS regulation of enteropathogenic Escherichia coli, also plays a part in mediating the Type III secretion system responsible for causing watery diarrhoea.[1]
This Type III secretion system is responsible for causing attaching and effacing intestinal lesions, which in turn lead to watery diarrhoea. The disease in found primarily in developing countries and can have drastic effects due to water and electrolyte loss in already malnutritioned children.
Jay Mellies and his colleagues discovered that enteropathogenic Escherichia coli that contained a mutation encoding for an uncleavable Lex A protein showed reduced secretions and thus reduced pathogenicity.
In 2005 the same protein was found to be responsible for inducing mutations during SOS response in E. coli following specific antibiotic pressures.[2] It was found that mutant E. coli strains containing an uncleavable Lex A protein were unable to induce mutations and thus unable to acquire antibiotic resistance. This means that by rendering E. coli unable to cleave Lex A they have decreased virulence factors and a malfunction in producing mutations that may allow them to become resistant to antibiotics. It is like exposing Superman to Kryptonite,[3] we can make them weak and unable to use their superpowers.
References:
1 Mellies, J.L. et al. (2007) SOS Regulation of the Type III Secretion System of Enteropathogenic Escherichia coli, Journal of Bacteriology, April, p. 2863-2872
2 Cirz, R.T. et al. (2005) Inhibition of mutation and combating the evolution of antibiotic resistance. PLoS Biology 3, e176
3 http://site.supermanthrutheages.com/Encyclopaedia/kryptonite.php (accessed on 9/10/07)
This blog was written by Ivana Ferreira 41214631
