scholarly journals Mechanism of phosphate sensing and signaling revealed by rice SPX1-PHR2 complex structure

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jia Zhou ◽  
Qinli Hu ◽  
Xinlong Xiao ◽  
Deqiang Yao ◽  
Shenghong Ge ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Steric Hindrance ◽  
Complex Structure ◽  
Transcription Activation ◽  
Plant Nutrient ◽  
Inositol Polyphosphates ◽  
Pi Homeostasis ◽  
Phosphate Sensing ◽  
Dual Mechanism

AbstractPhosphate, a key plant nutrient, is perceived through inositol polyphosphates (InsPs) by SPX domain-containing proteins. SPX1 an inhibit the PHR2 transcription factor to maintain Pi homeostasis. How SPX1 recognizes an InsP molecule and represses transcription activation by PHR2 remains unclear. Here we show that, upon binding InsP6, SPX1 can disrupt PHR2 dimers and form a 1:1 SPX1-PHR2 complex. The complex structure reveals that SPX1 helix α1 can impose a steric hindrance when interacting with the PHR2 dimer. By stabilizing helix α1, InsP6 allosterically decouples the PHR2 dimer and stabilizes the SPX1-PHR2 interaction. In doing so, InsP6 further allows SPX1 to engage with the PHR2 MYB domain and sterically block its interaction with DNA. Taken together, our results suggest that, upon sensing the surrogate signals of phosphate, SPX1 inhibits PHR2 via a dual mechanism that attenuates dimerization and DNA binding activities of PHR2.

scholarly journals Multiple layers of regulation of human heat shock transcription factor 1.

1995 ◽  
Vol 15 (8) ◽  
pp. 4319-4330 ◽  
Author(s):  
J Zuo ◽  
D Rungger ◽  
R Voellmy
Keyword(s):  
Transcription Factor ◽  
Heat Shock ◽  
Dna Binding ◽  
Cell Activation ◽  
Transcription Activation ◽  
Heat Shock Transcription Factor ◽  
Activation Domain ◽  
Sequence Element ◽  
Transcription Activation Domain ◽  
Transcription Factor 1

Upon heat stress, monomeric human heat shock transcription factor 1 (hHSF1) is converted to a trimer, acquires DNA-binding ability, is transported to the nucleus, and becomes transcriptionally competent. It was not known previously whether these regulatory changes are caused by a single activation event or whether they occur independently from one another, providing a multilayered control that may prevent inadvertant activation of hHSF1. Comparison of wild-type and mutant hHSF1 expressed in Xenopus oocytes and human HeLa cells suggested that retention of hHSF1 in the monomeric form depends on hydrophobic repeats (LZ1 to LZ3) and a carboxy-terminal sequence element in hHSF1 as well as on the presence of a titratable factor in the cell. Oligomerization of hHSF1 appears to induce DNA-binding activity as well as to uncover an amino-terminally located nuclear localization signal. A mechanism distinct from that controlling oligomerization regulates the transcriptional competence of hHSF1. Components of this mechanism were mapped to a region, including LZ2 and nearby sequences downstream from LZ2, that is clearly separated from the carboxy-terminally located transcription activation domain(s). We propose the existence of a fold-back structure that masks the transcription activation domain in the unstressed cell but is opened up by modification of hHSF1 and/or binding of a factor facilitating hHSF1 unfolding in the stressed cell. Activation of hHSF1 appears to involve at least two independently regulated structural transitions.

scholarly journals Functional analysis of the competence transcription factor ComK of Bacillus subtilis by characterization of truncation variants

Microbiology ◽  
2006 ◽  
Vol 152 (2) ◽  
pp. 473-483 ◽  
Author(s):  
Kim A. Susanna ◽  
Fabrizia Fusetti ◽  
Andy-Mark W. H. Thunnissen ◽  
Leendert W. Hamoen ◽  
Oscar P. Kuipers
Keyword(s):  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Dna Binding ◽  
Protein Interactions ◽  
Transcription Activation ◽  
Wild Type ◽  
Protein Protein Interactions ◽  
Protein Dna Interactions ◽  
Lower Protein

The competence transcription factor ComK is the master regulator of competence development in Bacillus subtilis. In the regulatory pathway, ComK is involved in different interactions: (i) protein–DNA interactions to stimulate transcription of ComK-dependent genes and (ii) protein–protein interactions, divided into interactions with other proteins and interactions between ComK proteins involving oligomerization. The fact that ComK displays different types of interactions suggests the presence of specific, distinct domains in the protein. This paper describes a search for functional domains, by constructing ComK truncation variants, which were tested for DNA binding, oligomerization and transcription activation. Truncations at the C-terminal end of ComK demonstrated the requirement of this part for transcription activation, but not for DNA binding. The C-terminal region is probably involved in oligomerization of ComK-dimers into tetramers. Surprisingly, a ComK truncation variant lacking 9 aa from the N-terminal end (ΔN9ComK) showed higher transcription activation than wild-type ComK, when expressed in Lactococcus lactis. However, in B. subtilis, transcription activation by ΔN9ComK was twofold lower than that by wild-type ComK, resulting from a five- to sixfold lower protein level of ComKΔN9. Thus, relatively, ΔN9ComK is more active in transcription activation than wild-type ComK. These results suggest that the presence of this N-terminal extension on ComK is a trade-off between high transcription activation and a thus far unidentified role in regulation of ComK.

Genetic analysis of theSalmonellatranscription factor HilA

2008 ◽  
Vol 54 (10) ◽  
pp. 854-860 ◽  
Author(s):  
Rebecca A. Daly ◽  
C. Phoebe Lostroh
Keyword(s):  
Amino Acids ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Dna Binding ◽  
Genetic Analysis ◽  
Transcription Activation ◽  
Winged Helix ◽  
Activation Domains

HilA, a Salmonella transcription factor, activates the invF-1 and prgH promoters through binding to the HilA box, which contains 2 copies of a TTKHAT motif separated by a T centered at –45 relative to the start sites of transcription. The N-terminal 112 amino acids of HilA are similar to winged helix-turn-helix DNA binding/transcription activation domains (wHTH DBDs). The remaining 441 amino acids are not similar in sequence to any other well-characterized transcription factors. Here, we report that the wHTH DBD is essential for activation of both promoters, but amino acids 113–554 are only required for normal activation of invF-1. Some alanine substitutions in the putative α loop, which connects the recognition and positioning helices in wHTH DBDs, cause a loss-of-activation phenotype. A hilA allele encoding a protein with an alanine substituted for arginine at position 71 in the α loop has a loss-of-activation defect exclusively at the prgH promoter. The results suggest distinct roles for one or more domains formed by amino acids 113–554 and for arginine 71 in activation of the 2 promoters.

scholarly journals A Single, Specific Thymine Mutation in the ComK-Binding Site Severely Decreases Binding and Transcription Activation by the Competence Transcription Factor ComK of Bacillus subtilis

2007 ◽  
Vol 189 (13) ◽  
pp. 4718-4728 ◽  
Author(s):  
Kim A. Susanna ◽  
Aleksandra M. Mironczuk ◽  
Wiep Klaas Smits ◽  
Leendert W. Hamoen ◽  
Oscar P. Kuipers
Keyword(s):  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Dna Binding ◽  
Consensus Sequence ◽  
Transcription Activation ◽  
Specific Sequence ◽  
Flexible Spacer ◽  
Specific Position ◽  
Dna Binding Affinity ◽  
In Silico Analyses

ABSTRACT The competence transcription factor ComK plays a central role in competence development in Bacillus subtilis by activating the transcription of the K regulon. ComK-activated genes are characterized by the presence of a specific sequence to which ComK binds, a K-box, in their upstream DNA region. Each K-box consists of two AT-boxes with the consensus sequence AAAA-(N)5-TTTT, which are separated by a flexible spacer resulting in either two, three, or four helical turns between the starting nucleotides of the repeating AT-box units. In this study, the effects of potential determinants of ComK regulation in K-boxes were investigated by testing ComK's transcription activation and DNA-binding affinity on altered K-boxes with mutations either in the spacer between the AT-boxes or in the consensus sequence of the AT-boxes. The most striking result demonstrates the importance of the second thymine base in the AT-boxes. Mutation of this T into a guanine resulted in a threefold reduction in transcription activation and DNA binding by ComK. Transcription activation, as well as DNA binding, was almost completely abolished when both AT-boxes contained a T2-to-G mutation. This result was corroborated by in silico analyses demonstrating that a combination of mutations at the T2 positions of both AT-boxes is not found among any ComK-activated K-boxes, indicating that at least one consensus T2 position is required to maintain a functional K-box. The results suggest an important structural role for T2 in ComK binding, probably by its specific position in the minor groove of the DNA.

scholarly journals Maximal Stimulation of Meiotic Recombination by a Yeast Transcription Factor Requires the Transcription Activation Domain and a DNA-Binding Domain

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 101-115 ◽  
Author(s):  
David T Kirkpatrick ◽  
Qingqing Fan ◽  
Thomas D Petes
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Meiotic Recombination ◽  
Binding Sites ◽  
Transcription Activation ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Activation Domain ◽  
Recombination Hotspot ◽  
Transcription Activation Domain

Abstract The DNA sequences located upstream of the yeast HIS4 represent a very strong meiotic recombination hotspot. Although the activity of this hotspot requires the transcription activator Rap1p, the level of HIS4 transcription is not directly related to the level of recombination. We find that the recombination-stimulating activity of Rap1p requires the transcription activation domain of the protein. We show that a hybrid protein with the Gal4p DNA-binding domain and the Rap1p activation domain can stimulate recombination in a strain in which Gal4p-binding sites are inserted upstream of HIS4. In addition, we find recombination hotspot activity associated with the Gal4p DNA-binding sites that is independent of known transcription factors. We suggest that yeast cells have two types of recombination hotspots, α (transcription factor dependent) and β (transcription factor independent).

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