Author:
Hidalgo Patricia,Ansari Aseem Z.,Schmidt Peter,Hare Brian,Simkovich Natasha,Farrell Susan,Shin Eun Ji,Ptashne Mark,Wagner Gerhard
Abstract
The GAL4 dimerization domain (GAL4-dd) is a powerful transcriptional activator when tethered to DNA in a cell bearing a mutant of the GAL11 protein, named GAL11P. GAL11P (like GAL11) is a component of the RNA–polymerase II holoenzyme. Nuclear magnetic resonance (NMR) studies of GAL4-dd revealed an elongated dimer structure with C2symmetry containing three helices that mediate dimerization via coiled-coil contacts. The two loops between the three coiled coils form mobile bulges causing a variation of twist angles between the helix pairs. Chemical shift perturbation analysis mapped the GAL11P-binding site to the C-terminal helix α3 and the loop between α1 and α2. One GAL11P monomer binds to one GAL4-dd dimer rendering the dimer asymmetric and implying an extreme negative cooperativity mechanism. Alanine-scanning mutagenesis of GAL4-dd showed that the NMR-derived GAL11P-binding face is crucial for the novel transcriptional activating function of the GAL4-dd on GAL11P interaction. The binding of GAL4 to GAL11P, although an artificial interaction, represents a unique structural motif for an activating region capable of binding to a single target to effect gene expression.
Publisher
Cold Spring Harbor Laboratory
Subject
Developmental Biology,Genetics
Cited by
40 articles.
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