Leading role of TBP in the Establishment of Complexity in Eukaryotic Transcription Initiation Systems

While both archaeal and eukaryotic transcription initiation systems utilize TBP (TATA box-binding protein) and TFIIB (transcription factor IIB), eukaryotic systems include larger numbers of initiation factors. It remains uncertain how eukaryotic transcription initiation systems have evolved. Here, we investigate the evolutionary development of TBP and TFIIB, each of which has an intramolecular direct repeat, using two evolutionary indicators. Inter-repeat sequence dissimilarity (dDR, distance between direct repeats) indicates that the asymmetry of two repeats in TBP and TFIIB has gradually increased during evolution. Interspecies sequence diversity (PD, phylogenetic diversity) indicates that the resultant asymmetric structure, which is related to the ability to interact with multiple factors, diverged in archaeal TBP and archaeal/eukaryotic TFIIB during evolution. Our findings suggest that eukaryotic TBP initially acquired multiple Eukarya-specific interactors through asymmetric evolution of the two repeats. After the asymmetric TBP generated the complexity of the eukaryotic transcription initiation systems, its diversification halted and its asymmetric structure spread throughout eukaryotic species

Crystal Structure of the DNA-binding Domain of the LysR-type Transcriptional Regulator CbnR in Complex with a DNA Fragment of the Recognition-binding Site in the Promoter Region

LysR‐type transcriptional regulators (LTTR s) are among the most abundant transcriptional regulators in bacteria. CbnR is an LTTR derived from Cupriavidus necator (formerly Alcaligenes eutrophus or Ralstonia eutropha ) NH 9 and is involved in transcriptional activation of the cbnABCD genes encoding chlorocatechol degradative enzymes. CbnR interacts with a cbnA promoter region of approximately 60 bp in length that contains the recognition‐binding site (RBS ) and activation‐binding site (ABS ). Upon inducer binding, CbnR seems to undergo conformational changes, leading to the activation of the transcription. Since the interaction of an LTTR with RBS is considered to be the first step of the transcriptional activation, the CbnR–RBS interaction is responsible for the selectivity of the promoter to be activated. To understand the sequence selectivity of CbnR, we determined the crystal structure of the DNA ‐binding domain of CbnR in complex with RBS of the cbnA promoter at 2.55 Å resolution. The crystal structure revealed details of the interactions between the DNA ‐binding domain and the promoter DNA . A comparison with the previously reported crystal structure of the DNA ‐binding domain of BenM in complex with its cognate RBS showed several differences in the DNA interactions, despite the structural similarity between CbnR and BenM. These differences explain the observed promoter sequence selectivity between CbnR and BenM. Particularly, the difference between Thr33 in CbnR and Ser33 in BenM appears to affect the conformations of neighboring residues, leading to the selective interactions with DN

Crystal structure of the DNA

LysR‐type transcriptional regulators (LTTR s) are among the most abundant transcriptional regulators in bacteria. CbnR is an LTTR derived from Cupriavidus necator (formerly Alcaligenes eutrophus or Ralstonia eutropha ) NH 9 and is involved in transcriptional activation of the cbnABCD genes encoding chlorocatechol degradative enzymes. CbnR interacts with a cbnA promoter region of approximately 60 bp in length that contains the recognition‐binding site (RBS ) and activation‐binding site (ABS ). Upon inducer binding, CbnR seems to undergo conformational changes, leading to the activation of the transcription. Since the interaction of an LTTR with RBS is considered to be the first step of the transcriptional activation, the CbnR–RBS interaction is responsible for the selectivity of the promoter to be activated. To understand the sequence selectivity of CbnR, we determined the crystal structure of the DNA ‐binding domain of CbnR in complex with RBS of the cbnA promoter at 2.55 Å resolution. The crystal structure revealed details of the interactions between the DNA ‐binding domain and the promoter DNA . A comparison with the previously reported crystal structure of the DNA ‐binding domain of BenM in complex with its cognate RBS showed several differences in the DNA interactions, despite the structural similarity between CbnR and BenM. These differences explain the observed promoter sequence selectivity between CbnR and BenM. Particularly, the difference between Thr33 in CbnR and Ser33 in BenM appears to affect the conformations of neighboring residues, leading to the selective interactions with DN

Structural basis of the strict specificity of a bacterial GH31 α-1,3-glucosidase for nigerooligosaccharides

publishe

Positive and Negative Regulation of the Cardiovascular Transcription Factor KLF5 by p300 and the Oncogenic Regulator SET through Interaction and Acetylation on the DNA-Binding Domain

Here we show a novel pathway of transcriptional regulation of a DNA-binding transcription factor by coupled interaction and modification (e.g., acetylation) through the DNA-binding domain (DBD). The oncogenic regulator SET was isolated by affinity purification of factors interacting with the DBD of the cardiovascular transcription factor KLF5. SET negatively regulated KLF5 DNA binding, transactivation, and cell-proliferative activities. Down-regulation of the negative regulator SET was seen in response to KLF5-mediated gene activation. The coactivator/acetylase p300, on the other hand, interacted with and acetylated KLF5 DBD, and activated its transcription. Interestingly, SET inhibited KLF5 acetylation, and a nonacetylated mutant of KLF5 showed reduced transcriptional activation and cell growth complementary to the actions of SET. These findings suggest a new pathway for regulation of a DNA-binding transcription factor on the DBD through interaction and coupled acetylation by two opposing regulatory factors of a coactivator/acetylase and a negative cofactor harboring activity to inhibit acetylation

Structural analysis reveals TLR7 dynamics underlying antagonism

A series of Toll-like receptor 7 (TLR7)-specific antagonists and extensive structural analysis reveal the open conformation of the receptor and the structural basis of TLR7 antagonism. One of the compounds shows efficacy in treating mouse model of systemic lupus erythematosus