H-DNA and Z-DNA in the mouse c-Ki-ras promoter.

AUTOR(ES)

Pestov, D G

RESUMO

The mouse c-Ki-ras protooncogene promoter contains a homopurine-homopyrimidine domain that exhibits S1 nuclease sensitivity in vitro. We have studied the structure of this DNA region in a supercoiled state using a number of chemical probes for non-B DNA conformations including diethyl pyrocarbonate, osmium tetroxide, chloroacetaldehyde, and dimethyl sulfate. The results demonstrate that two types of unusual DNA structures formed under different environmental conditions. A 27-bp homopurine-homopyrimidine mirror repeat adopts a triple-helical H-DNA conformation under mildly acidic conditions. This H-DNA seems to account for the S1 hypersensitivity of the promoter in vitro, since the observed pattern of S1 hypersensitivity at a single base level fits well with the H-DNA formation. Under conditions of neutral pH we have detected Z-DNA created by a (CG)5-stretch, located adjacent to the homopurine-homopyrimidine mirror repeat. The ability of the promoter DNA segment to form non-B structures has implications for models of gene regulation.

Documentos Relacionados

• Structural and functional characterization of the promoter region of the mouse c-Ki-ras gene.
• Rsal polymorphism in c-Ki-ras
• Transcriptional activity of the homopurine-homopyrimidine repeat of the c-Ki-ras promoter is independent of its H-forming potential.
• c-Ki-ras oncogene amplification and FGF2 signaling pathways in the mouse Y1 adrenocortical cell line
• Absence of c-Ki-ras gene mutation in malignant and premalignant Barrett's oesophagus