1887

Abstract

sp. strain PCL1171 undergoes reversible colony phase variation between opaque phase I and translucent phase II colonies, which is dependent on spontaneous mutations in the regulatory genes and . Mutation of the gene and constitutive expression of increases the frequency at which mutants appear 1000- and 10-fold, respectively. Experiments were designed to study the relationship between , and . These studies showed that (i) a functional system is required for the expression of , (ii) RpoS suppresses the expression of and therefore increases the frequency of mutants, and (iii) upon mutation of and , the expression of is increased. Mutation of abolishes suppression of expression in stationary growth, suggesting that additional -dependent factors are involved in this suppression. In conclusion, inefficient mutation repair via MutS, of which the expression is influenced by / itself and by in combination with other factors, contributes to the high frequency of mutations accumulating in /. The role of RpoS in the growth advantage of a mutant was analysed, and mutation of only reduced the length of the lag phase, but did not affect the growth rate, suggesting a role for both RpoS and a reduction of metabolic load in the growth advantage of a mutant.

Keyword(s): RT-PCR, real-time PCR
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2005-05-01
2019-11-13
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