Sequence Analysis of Mutations Arising during Prolonged Starvation of Salmonella Typhimurium
AUTOR(ES)
Prival, M. J.
RESUMO
We have examined the effects of prolonged histidine deprivation on the reversion of Salmonella typhimurium histidine auxotrophs containing either hisG46, a missense mutation (CTC -> CCC), or hisG428, an ochre mutation (CAA -> TAA). Both of these mutants can revert to His(+) via intragenic and extragenic mechanisms. Whereas the hisG46 mutant site consists of G/C base pairs, extragenic suppression of hisG46 requires mutation at an A/T site. Conversely, the hisG428 site itself contains only A/T base pairs, and extragenic suppression of hisG428 occurs principally at G/C sites. Thus, by examining the mutational spectrum of hisG46 and hisG428 revertants that occurred in the presence and in the absence of histidine, it was possible to determine the effects of histidine starvation on mutations at G/C vs. A/T sites as well as on intragenic sites vs. extragenic suppressor sites. Using DNA-colony hybridization, we determined the DNA sequences of over 1300 hisG46 and hisG428 revertants. Histidine-independent revertants that arose during growth in liquid medium that contained histidine included both intragenic and extragenic suppressor mutations. The relative frequency of such extragenic suppressors was greatly reduced among the His(+) revertants that were isolated after 5-10 days of histidine starvation on agar medium. Moreover, DNA sequence analysis revealed striking differences in the distribution of particular transversions at the hisG428 locus in revertants arising after prolonged histidine starvation as compared to those arising after growth in the presence of histidine.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1205137Documentos Relacionados
- Genetic Analysis of thr Mutations in Salmonella typhimurium
- Phosphate starvation regulon of Salmonella typhimurium.
- Evolution of microbial diversity during prolonged starvation
- Amino acid metabolism during prolonged starvation
- Flow cytometric analysis of the cellular DNA content of Salmonella typhimurium and Alteromonas haloplanktis during starvation and recovery in seawater.