Scorching solar radiation. Exposure to free radicals. Mutagenic conditions that the cosmetic industry have made us well aware of. They are also examples of mutagenic conditions that affect bacterial DNA, initiating something called the SOS response. This mechanism is involved in nucleotide excision repair and recombinational repair. In the latter situation, it is their final chance for survival under harmful conditions, with badly damaged DNA being repaired by error-prone DNA polymerase. The objective is that at least one member of the struggling population will acquire a mutation to overcome the new deleterious environment. These conditions were thought to be only those conducive to DNA damage, such as UV light, and exposure to mutagenic chemicals. It now appears, however, that a non-mutagenic physical stress can also stimulate the same pathway of last resort.
In a study conducted by Aertson et al. (2005), hydrostatic pressure was applied to Escherichia coli. Amazingly, it was found that this non-mutagenic stress also initiated the SOS response. A novel cellular response is induced in response to a stress that cannot thermodynamically affect DNA integrity. Through further study of the SOS regulon, it is hoped that we may one day have a means of overcoming antibiotic resistant bacteria, which threatens to be a huge global problem.
Merran Neilsen
41203952
Primary Reference
Aertsen.A, Michiels..C.W. 2005 Mrr stimulates the SOS response after high pressure stress in escherichia coli. Journal of Molecular Microbiology. 58.5. 1381-1391.
