SKN-1 domain folding and basic region monomer stabilization upon DNA binding
AUTOR(ES)
Carroll, Adam S.
FONTE
Cold Spring Harbor Laboratory Press
RESUMO
The SKN-1 transcription factor specifies early embryonic cell fates in Caenorhabditis elegans. SKN-1 binds DNA at high affinity as a monomer, by means of a basic region like those of basic-leucine zipper (bZIP) proteins, which bind DNA only as dimers. We have investigated how the SKN-1 DNA-binding domain (the Skn domain) promotes stable binding of a basic region monomer to DNA. A flexible arm at the Skn domain amino terminus binds in the minor groove, but a support segment adjacent to the carboxy-terminal basic region can independently stabilize basic region–DNA binding. Off DNA, the basic region and arm are unfolded and, surprisingly, the support segment forms a molten globule of four α-helices. On binding DNA, the Skn domain adopts a tertiary structure in which the basic region helix extends directly from a support segment α-helix, which is required for binding. The remainder of the support segment anchors this uninterrupted helix on DNA, but leaves the basic region exposed in the major groove. This is similar to how the bZIP basic region extends from the leucine zipper, indicating that positioning and cooperative stability provided by helix extension are conserved mechanisms that promote binding of basic regions to DNA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=275399Documentos Relacionados
- The solution structure of the DNA-binding domain of Skn-1
- The SKN-1 Amino-Terminal Arm Is a DNA Specificity Segment
- SKN-1 links C. elegans mesendodermal specification to a conserved oxidative stress response
- Skn-1: Evidence for a bipartite recognition helix in DNA binding
- The basic region of Fos mediates specific DNA binding.