Specific recognition of cruciform DNA by nuclear protein HMG1.

Cruciform DNA, a non-double helix form of DNA, can be generated as an intermediate in genetic recombination as well as from palindromic sequences under the effect of supercoiling. Eukaryotic cells are equipped with a DNA-binding protein that selectively recognizes cruciform DNA. Biochemical and immunological data showed that this protein is HMG1, an evolutionarily conserved, essential, and abundant component of the nucleus. The interaction with a ubiquitous protein points to a critical role for cruciform DNA conformations.