Transition of a cloned d(AT)n-d(AT)n tract to a cruciform in vivo.
AUTOR(ES)
Haniford, D B
RESUMO
A 34 base pair tract of the simple repeating dinucleotide d(AT)n-d(AT)n cloned into a 2.4 kb polylinker plasmid vector undergoes a structural transition in response to negative superhelical coiling. The transition has been characterized by 2 dimensional gel electrophoresis, mapping of S1, P1 and T7 endonuclease 1 sensitive sites, and mapping of sites that are sensitive to modification by bromoacetaldehyde. After S1 nuclease treatment it is possible to trap supercoiled species that are nicked on one or both strands near the center of the palindrome. These data show that the alternate state adopted by the d(AT)n-dAT)n insert is a cruciform rather than a Z conformation. Unlike other B-cruciform transitions the transition in d(AT)n-d(AT)n has a low activation energy and the transition is facilitated by the presence of magnesium ions. Evidence from in-vivo topoisomer distributions is presented which shows that under conditions of blocked protein synthesis the d(AT)n-d(AT)n insert will spontaneously adopt the cruciform state in-vivo in E. coli.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=321792Documentos Relacionados
- Transcriptionally driven cruciform formation in vivo.
- Actinomycin D facilitates transition of AT domains in molecules of sequence (AT)nAGCT(AT)n to a DNAse I detectable alternating structure.
- Correct transcription of a cloned mouse immunoglobulin gene in vivo.
- Intermediate range effects in DNA. I: Low pH/stress induced conformational changes in the vicinity of an extruded d(AT)n.d(AT) in cruciform.
- Purified glucocorticoid receptors bind selectively in vitro to a cloned DNA fragment that mediates a delayed secondary response to glucocorticoids in vivo.
