Cruciform structures are a common DNA feature important for regulating biological processes
1 Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, Brno, 612 65, Czech Republic
2 Division of Stem Cell and Developmental Biology, Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
3 Cancer Genomics & Proteomics, Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
BMC Molecular Biology 2011, 12:33 doi:10.1186/1471-2199-12-33Published: 5 August 2011
DNA cruciforms play an important role in the regulation of natural processes involving DNA. These structures are formed by inverted repeats, and their stability is enhanced by DNA supercoiling. Cruciform structures are fundamentally important for a wide range of biological processes, including replication, regulation of gene expression, nucleosome structure and recombination. They also have been implicated in the evolution and development of diseases including cancer, Werner's syndrome and others.
Cruciform structures are targets for many architectural and regulatory proteins, such as histones H1 and H5, topoisomerase IIβ, HMG proteins, HU, p53, the proto-oncogene protein DEK and others. A number of DNA-binding proteins, such as the HMGB-box family members, Rad54, BRCA1 protein, as well as PARP-1 polymerase, possess weak sequence specific DNA binding yet bind preferentially to cruciform structures. Some of these proteins are, in fact, capable of inducing the formation of cruciform structures upon DNA binding. In this article, we review the protein families that are involved in interacting with and regulating cruciform structures, including (a) the junction-resolving enzymes, (b) DNA repair proteins and transcription factors, (c) proteins involved in replication and (d) chromatin-associated proteins. The prevalence of cruciform structures and their roles in protein interactions, epigenetic regulation and the maintenance of cell homeostasis are also discussed.