Essential residues for DNA binding activity of ManR fromAnabaena sp. PCC 7120

2006 ◽  
Vol 56 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Wei Huang ◽  
Qingyu Wu ◽  
Min Li ◽  
Xingguo Liu
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Pcc 7120

scholarly journals Mutagenesis of hetR Reveals Amino Acids Necessary for HetR Function in the Heterocystous Cyanobacterium Anabaena sp. Strain PCC 7120

2007 ◽  
Vol 189 (6) ◽  
pp. 2460-2467 ◽  
Author(s):  
Douglas D. Risser ◽  
Sean M. Callahan
Keyword(s):  
Dna Binding ◽  
Genetic Selection ◽  
Inducible Promoter ◽  
Binding Activity ◽  
Filamentous Cyanobacterium ◽  
Wild Type ◽  
Mobility Shift ◽  
Heterocyst Differentiation ◽  
Dna Binding Activity ◽  
Pcc 7120

ABSTRACT HetR is the master regulator of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Genetic selection was used to identify 33 amino acid substitutions in HetR that reduced the proportion of cells undergoing heterocyst differentiation to less than 2%. Conservative substitutions in the wild-type HetR protein revealed three mutations that dramatically reduced the amount of heterocyst differentiation when the mutant allele was present in place of the wild-type allele on a replicating plasmid in a mutant lacking hetR on the chromosome. An H69Y substitution resulted in heterocyst formation among less than 0.1% of cells, and D17E and G36A substitutions resulted in a Het− phenotype, compared to heterocyst formation among approximately 25% of cells with the wild-type hetR under the same conditions. The D17E substitution prevented DNA binding activity exhibited by wild-type HetR in mobility shift assays, whereas G36A and H69Y substitutions had no affect on DNA binding. D17E, G36A, and H69Y substitutions also resulted in higher levels of the corresponding HetR protein than of the wild-type protein when each was expressed from an inducible promoter in a hetR deletion strain, suggesting an effect on HetR protein turnover. Surprisingly, C48A and S152A substitutions, which were previously reported to result in a Het− phenotype, were found to have no effect on heterocyst differentiation or patterning when the corresponding mutations were introduced into an otherwise wild-type genetic background in Anabaena sp. strain PCC 7120. The clustering of mutations that satisfied the positive selection near the amino terminus suggests an important role for this part of the protein in HetR function.

scholarly journals Heme binds to and inhibits the DNA-binding activity of the global regulator FurA fromAnabaenasp. PCC 7120

FEBS Letters ◽  
2004 ◽  
Vol 577 (1-2) ◽  
pp. 35-41 ◽  
Author(s):  
José A. Hernández ◽  
M.Luisa Peleato ◽  
Marı́a F. Fillat ◽  
M.Teresa Bes
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Global Regulator ◽  
Dna Binding Activity ◽  
Pcc 7120

scholarly journals New insights into the role of Fur proteins: FurB (All2473) from Anabaena protects DNA and increases cell survival under oxidative stress

2009 ◽  
Vol 418 (1) ◽  
pp. 201-207 ◽  
Author(s):  
Sara López-Gomollón ◽  
Emma Sevilla ◽  
M. Teresa Bes ◽  
M. Luisa Peleato ◽  
María F. Fillat
Keyword(s):  
Oxidative Stress ◽  
Dna Binding ◽  
Binding Activity ◽  
Filamentous Cyanobacterium ◽  
Factors Affecting ◽  
Dna Binding Activity ◽  
Low Concentrations ◽  
Cyanobacterium Anabaena ◽  
Pcc 7120

Fur (ferric uptake regulator) is a prokaryotic transcriptional regulator that controls a large number of genes mainly related to iron metabolism. Several Fur homologues with different physiological roles are frequently found in the same organism. The genome of the filamentous cyanobacterium Anabaena (Nostoc) sp. PCC 7120 codes for three different fur genes. FurA is an essential protein involved in iron homoeostasis that also modulates dinitrogen fixation. FurA interacts with haem, impairing its DNA-binding ability. To explore functional differences between Fur homologues in Anabaena, factors affecting their regulation, as well as some biochemical characteristics, have been investigated. Although incubation of FurB with haem severely hinders its ability to interact with DNA, binding of haem to FurC could not be detected. Oxidative stress enhances the transcription of the three fur genes, especially that of furB and furC. In addition, overexpression of FurA and FurB in Escherichia coli increases survival when the cells are challenged with H2O2 or Methyl Viologen (paraquat), a superoxide-anion-generating reagent. When present in saturating concentrations, FurB exhibits unspecific DNA-binding activity and protects DNA from cleavage produced by hydroxyl radicals or DNaseI. On the basis of these results, we suggest that, whereas at low concentrations FurB would act as a member of the Fur family, at saturating concentrations FurB protects DNA, showing a DNA-protection-during-starvation-like behaviour.

scholarly journals Structure of the p53/RNA polymerase II assembly

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Shu-Hao Liou ◽  
Sameer K. Singh ◽  
Robert H. Singer ◽  
Robert A. Coleman ◽  
Wei-Li Liu
Keyword(s):  
Dna Binding ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Conformational Changes ◽  
P53 Protein ◽  
Binding Activity ◽  
Transactivation Domain ◽  
Pol Ii ◽  
Dna Binding Activity ◽  
Regulated Gene Expression

AbstractThe tumor suppressor p53 protein activates expression of a vast gene network in response to stress stimuli for cellular integrity. The molecular mechanism underlying how p53 targets RNA polymerase II (Pol II) to regulate transcription remains unclear. To elucidate the p53/Pol II interaction, we have determined a 4.6 Å resolution structure of the human p53/Pol II assembly via single particle cryo-electron microscopy. Our structure reveals that p53’s DNA binding domain targets the upstream DNA binding site within Pol II. This association introduces conformational changes of the Pol II clamp into a further-closed state. A cavity was identified between p53 and Pol II that could possibly host DNA. The transactivation domain of p53 binds the surface of Pol II’s jaw that contacts downstream DNA. These findings suggest that p53’s functional domains directly regulate DNA binding activity of Pol II to mediate transcription, thereby providing insights into p53-regulated gene expression.

scholarly journals Abundance Changes of the Response Regulator RcaC Require Specific Aspartate and Histidine Residues and Are Necessary for Normal Light Color Responsiveness

2008 ◽  
Vol 190 (21) ◽  
pp. 7241-7250 ◽  
Author(s):  
Lina Li ◽  
David M. Kehoe
Keyword(s):  
Dna Binding ◽  
Dynamic Range ◽  
Response Regulator ◽  
Red Light ◽  
Green Light ◽  
Binding Activity ◽  
Transcriptional Responses ◽  
Dna Binding Activity ◽  
Normal Light ◽  
Light Color

ABSTRACT RcaC is a large, complex response regulator that controls transcriptional responses to changes in ambient light color in the cyanobacterium Fremyella diplosiphon. The regulation of RcaC activity has been shown previously to require aspartate 51 and histidine 316, which appear to be phosphorylation sites that control the DNA binding activity of RcaC. All available data suggest that during growth in red light, RcaC is phosphorylated and has relatively high DNA binding activity, while during growth in green light RcaC is not phosphorylated and has less DNA binding activity. RcaC has also been found to be approximately sixfold more abundant in red light than in green light. Here we demonstrate that the light-controlled abundance changes of RcaC are necessary, but not sufficient, to direct normal light color responses. RcaC abundance changes are regulated at both the RNA and protein levels. The RcaC protein is significantly less stable in green light than in red light, suggesting that the abundance of this response regulator is controlled at least in part by light color-dependent proteolysis. We provide evidence that the regulation of RcaC abundance does not depend on any RcaC-controlled process but rather depends on the presence of the aspartate 51 and histidine 316 residues that have previously been shown to control the activity of this protein. We propose that the combination of RcaC abundance changes and modification of RcaC by phosphorylation may be necessary to provide the dynamic range required for transcriptional control of RcaC-regulated genes.

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