scholarly journals Protein oxidation mediated by heme-induced active site conversion specific for heme-regulated transcription factor, iron response regulator

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Chihiro Kitatsuji ◽  
Kozue Izumi ◽  
Shusuke Nambu ◽  
Masaki Kurogochi ◽  
Takeshi Uchida ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Oxidation ◽  
Active Site ◽  
Response Regulator ◽  
Iron Response Regulator

scholarly journals Effect of Environmental pH on Morphological Development of Candida albicans Is Mediated via the PacC-Related Transcription Factor Encoded by PRR2

1999 ◽  
Vol 181 (24) ◽  
pp. 7524-7530 ◽  
Author(s):  
Ana M. Ramon ◽  
Amalia Porta ◽  
William A. Fonzi
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Feedback Loop ◽  
Response Regulator ◽  
Morphological Development ◽  
Alkaline Ph ◽  
Ph Response ◽  
Related Transcription Factor ◽  
Ph Dependent

ABSTRACT The ability to respond to ambient pH is critical to the growth and virulence of the fungal pathogen Candida albicans. This response entails the differential expression of several genes affecting morphogenesis. To investigate the mechanism of pH-dependent gene expression, the C. albicans homolog of pacC, designated PRR2 (for pH response regulator), was identified and cloned. pacC encodes a zinc finger-containing transcription factor that mediates pH-dependent gene expression inAspergillus nidulans. Mutants lacking PRR2 can no longer induce the expression of alkaline-expressed genes or repress acid-expressed genes at alkaline pH. Although the mutation did not affect growth of the cells at acid or alkaline pH, the mutants exhibited medium-conditional defects in filamentation. PRR2was itself expressed in a pH-conditional manner, and its induction at alkaline pH was controlled by PRR1. PRR1 is homologous to palF, a regulator of pacC. Thus,PRR2 expression is controlled by a pH-dependent feedback loop. The results demonstrate that the pH response pathway ofAspergillus is conserved and that this pathway has been adapted to control dimorphism in C. albicans.

scholarly journals Investigation of the Role of Electrostatic Charge in Activation of the Escherichia coli Response Regulator CheY

2003 ◽  
Vol 185 (21) ◽  
pp. 6385-6391 ◽  
Author(s):  
Jenny G. Smith ◽  
Jamie A. Latiolais ◽  
Gerald P. Guanga ◽  
Sindhura Citineni ◽  
Ruth E. Silversmith ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Amino Acid ◽  
Active Site ◽  
Response Regulator ◽  
Residual Activity ◽  
Phosphoryl Group ◽  
Sensor Kinase ◽  
Amino Acid Substitutions ◽  
Flagellar Rotation

ABSTRACT In a two-component regulatory system, an important means of signal transduction in microorganisms, a sensor kinase phosphorylates a response regulator protein on an aspartyl residue, resulting in activation. The active site of the response regulator is highly charged (containing a lysine, the phosphorylatable aspartate, two additional aspartates involved in metal binding, and an Mg2+ ion), and introduction of the dianionic phosphoryl group results in the repositioning of charged moieties. Furthermore, substitution of one of the Mg2+-coordinating aspartates with lysine or arginine in the Escherichia coli chemotaxis response regulator CheY results in phosphorylation-independent activation. In order to examine the consequences of altered charge distribution for response regulator activity and to identify possible additional amino acid substitutions that result in phosphorylation-independent activation, we made 61 CheY mutants in which residues close to the site of phosphorylation (Asp57) were replaced by various charged amino acids. Most substitutions (47 of 61) resulted in the complete loss of CheY activity, as measured by the inability to support clockwise flagellar rotation. However, 10 substitutions, all introducing a new positive charge, resulted in the loss of chemotaxis but in the retention of some clockwise flagellar rotation. Of the mutants in this set, only the previously identified CheY13DK and CheY13DR mutants displayed clockwise activity in the absence of the CheA sensor kinase. The absence of negatively charged substitution mutants with residual activity suggests that the introduction of additional negative charges into the active site is particularly deleterious for CheY function. Finally, the spatial distribution of positions at which amino acid substitutions are functionally tolerated or not tolerated is consistent with the presently accepted mechanism of response regulator activation and further suggests a possible role for Met17 in signal transduction by CheY.

scholarly journals Mechanistic insights into heme-mediated transcriptional regulation via a bacterial manganese-binding iron regulator, iron response regulator (Irr)

2020 ◽  
Vol 295 (32) ◽  
pp. 11316-11325
Author(s):  
Dayeon Nam ◽  
Yuki Matsumoto ◽  
Takeshi Uchida ◽  
Mark R. O'Brian ◽  
Koichiro Ishimori
Keyword(s):  
Binding Site ◽  
Fluorescence Anisotropy ◽  
Response Regulator ◽  
Binding Activity ◽  
Control Element ◽  
Heme Binding ◽  
Cluster Region ◽  
Ice Binding ◽  
Iron Response Regulator ◽  
Ice Complex

The transcription factor iron response regulator (Irr) is a key regulator of iron homeostasis in the nitrogen-fixating bacterium Bradyrhizobium japonicum. Irr acts by binding to target genes, including the iron control element (ICE), and is degraded in response to heme binding. Here, we examined this binding activity using fluorescence anisotropy with a 6-carboxyfluorescein-labeled ICE-like oligomer (FAM-ICE). In the presence of Mn2+, Irr addition increased the fluorescence anisotropy, corresponding to formation of the Irr–ICE complex. The addition of EDTA to the Irr–ICE complex reduced fluorescence anisotropy, but fluorescence was recovered after Mn2+ addition, indicating that Mn2+ binding is a prerequisite for complex formation. Binding activity toward ICE was lost upon introduction of substitutions in a His-cluster region of Irr, revealing that Mn2+ binds to this region. We observed that the His-cluster region is also the heme binding site; results from fluorescence anisotropy and electrophoretic mobility shift analyses disclosed that the addition of a half-equivalent of heme dissociates Irr from ICE, likely because of Mn2+ release due to heme binding. We hypothesized that heme binding to another heme binding site, Cys-29, would also inhibit the formation of the Irr–ICE complex because it is proximal to the ICE binding site, which was supported by the loss of ICE binding activity in a Cys-29–mutated Irr. These results indicate that Irr requires Mn2+ binding to form the Irr–ICE complex and that the addition of heme dissociates Irr from ICE by replacing Mn2+ with heme or by heme binding to Cys-29.

scholarly journals Crystal Structure of the Response Regulator 02 Receiver Domain, the Essential YycF Two-Component System of Streptococcus pneumoniae in both Complexed and Native States

2004 ◽  
Vol 186 (9) ◽  
pp. 2872-2879 ◽  
Author(s):  
Colin J. Bent ◽  
Neil W. Isaacs ◽  
Timothy J. Mitchell ◽  
Alan Riboldi-Tunnicliffe
Keyword(s):  
Streptococcus Pneumoniae ◽  
Active Site ◽  
Response Regulator ◽  
Thermotoga Maritima ◽  
Two Component System ◽  
Environmental Signals ◽  
Receiver Domain ◽  
Two Component ◽  
Protein Sequence Homology ◽  
Two Component Signal Transduction

ABSTRACT A variety of bacterial cellular responses to environmental signals are mediated by two-component signal transduction systems comprising a membrane-associated histidine protein kinase and a cytoplasmic response regulator (RR), which interpret specific stimuli and produce a measured physiological response. In RR activation, transient phosphorylation of a highly conserved aspartic acid residue drives the conformation changes needed for full activation of the protein. Sequence homology reveals that RR02 from Streptococcus pneumoniae belongs to the OmpR subfamily of RRs. The structures of the receiver domains from four members of this family, DrrB and DrrD from Thermotoga maritima, PhoB from Escherichia coli, and PhoP from Bacillus subtilis, have been elucidated. These domains are globally very similar in that they are composed of a doubly wound α5β5; however, they differ remarkably in the fine detail of the β4-α4 and α4 regions. The structures presented here reveal a further difference of the geometry in this region. RR02 is has been shown to be the essential RR in the gram-positive bacterium S. pneumoniae R. Lange, C. Wagner, A. de Saizieu, N. Flint, J. Molnos, M. Stieger, P. Caspers, M. Kamber, W. Keck, and K. E. Amrein, Gene 237:223-234, 1999; J. P. Throup, K. K. Koretke, A. P. Bryant, K. A. Ingraham, A. F. Chalker, Y. Ge, A. Marra, N. G. Wallis, J. R. Brown, D. J. Holmes, M. Rosenberg, and M. K. Burnham, Mol. Microbiol. 35:566-576, 2000). RR02 functions as part of a phosphotransfer system that ultimately controls the levels of competence within the bacteria. Here we report the native structure of the receiver domain of RR02 from serotype 4 S. pneumoniae (as well as acetate- and phosphate-bound forms) at different pH levels. Two native structures at 2.3 Å, phased by single-wavelength anomalous diffraction (xenon SAD), and 1.85 Å and a third structure at pH 5.9 revealed the presence of a phosphate ion outside the active site. The fourth structure revealed the presence of an acetate molecule in the active site.

scholarly journals Conversion of Norepinephrine to 3,4-Dihdroxymandelic Acid in Escherichia coli Requires the QseBC Quorum-Sensing System and the FeaR Transcription Factor

2017 ◽  
Vol 200 (1) ◽  
Author(s):  
Sasikiran Pasupuleti ◽  
Nitesh Sule ◽  
Michael D. Manson ◽  
Arul Jayaraman
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Aromatic Amines ◽  
Response Regulator ◽  
Content Type ◽  
E Coli ◽  
Expression Of Genes ◽  
K 12 ◽  
Cognate Response Regulator

ABSTRACTThe detection of norepinephrine (NE) as a chemoattractant byEscherichia colistrain K-12 requires the combined action of the TynA monoamine oxidase and the FeaB aromatic aldehyde dehydrogenase. The role of these enzymes is to convert NE into 3,4-dihydroxymandelic acid (DHMA), which is a potent chemoattractant sensed by the Tsr chemoreceptor. These two enzymes must be induced by prior exposure to NE, and cells that are exposed to NE for the first time initially show minimal chemotaxis toward it. The induction of TynA and FeaB requires the QseC quorum-sensing histidine kinase, and the signaling cascade requires new protein synthesis. Here, we demonstrate that the cognate response regulator for QseC, the transcription factor QseB, is also required for induction. The related quorum-sensing kinase QseE appears not to be part of the signaling pathway, but its cognate response regulator, QseF, which is also a substrate for phosphotransfer from QseC, plays a nonessential role. The promoter of thefeaRgene, which encodes a transcription factor that has been shown to be essential for the expression oftynAandfeaB, has two predicted QseB-binding sites. One of these sites appears to be in an appropriate position to stimulate transcription from the P1promoter of thefeaRgene. This study unites two well-known pathways: one for expression of genes regulated by catecholamines (QseBC) and one for expression of genes required for metabolism of aromatic amines (FeaR, TynA, and FeaB). This cross talk allowsE. colito convert the host-derived and chemotactically inert NE into the potent bacterial chemoattractant DHMA.IMPORTANCEThe chemotaxis ofE. coliK-12 to norepinephrine (NE) requires the conversion of NE to 3,4-dihydroxymandleic acid (DHMA), and DHMA is both an attractant and inducer of virulence gene expression for a pathogenic enterohemorrhagicE. coli(EHEC) strain. The induction of virulence by DHMA and NE requires QseC. The results described here show that the cognate response regulator for QseC, QseB, is also required for conversion of NE into DHMA. Production of DHMA requires induction of a pathway involved in the metabolism of aromatic amines. Thus, the QseBC sensory system provides a direct link between virulence and chemotaxis, suggesting that chemotaxis to host signaling molecules may require that those molecules are first metabolized by bacterial enzymes to generate the actual chemoattractant.

scholarly journals Proposed Signal Transduction Role for Conserved CheY Residue Thr87, a Member of the Response Regulator Active-Site Quintet

1998 ◽  
Vol 180 (14) ◽  
pp. 3563-3569 ◽  
Author(s):  
Jeryl L. Appleby ◽  
Robert B. Bourret
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Response Regulator ◽  
Hydroxyl Group ◽  
Amino Acid Substitutions ◽  
Mutant Proteins ◽  
Hydroxy Amino Acid ◽  
Hydroxy Amino ◽  
Flagellar Rotation

ABSTRACT CheY serves as a structural prototype for the response regulator proteins of two-component regulatory systems. Functional roles have previously been defined for four of the five highly conserved residues that form the response regulator active site, the exception being the hydroxy amino acid which corresponds to Thr87 in CheY. To investigate the contribution of Thr87 to signaling, we characterized, genetically and biochemically, several cheY mutants with amino acid substitutions at this position. The hydroxyl group appears to be necessary for effective chemotaxis, as a Thr→Ser substitution was the only one of six tested which retained a Che+ swarm phenotype. Although nonchemotactic, cheY mutants with amino acid substitutions T87A and T87C could generate clockwise flagellar rotation either in the absence of CheZ, a protein that stimulates dephosphorylation of CheY, or when paired with a second site-activating mutation, Asp13→Lys, demonstrating that a hydroxy amino acid at position 87 is not essential for activation of the flagellar switch. All purified mutant proteins examined phosphorylated efficiently from the CheA kinase in vitro but were impaired in autodephosphorylation. Thus, the mutant CheY proteins are phosphorylated to a greater degree than wild-type CheY yet support less clockwise flagellar rotation. The data imply that Thr87 is important for generating and/or stabilizing the phosphorylation-induced conformational change in CheY. Furthermore, the various position 87 substitutions differentially affected several properties of the mutant proteins. The chemotaxis and autodephosphorylation defects were tightly linked, suggesting common structural elements, whereas the effects on self-catalyzed and CheZ-mediated dephosphorylation of CheY were uncorrelated, suggesting different structural requirements for the two dephosphorylation reactions.

scholarly journals Synergistic Regulation of Competence Development in Bacillus subtilis by Two Rap-Phr Systems

2005 ◽  
Vol 187 (13) ◽  
pp. 4353-4361 ◽  
Author(s):  
Cristina Bongiorni ◽  
Shu Ishikawa ◽  
Sophie Stephenson ◽  
Naotake Ogasawara ◽  
Marta Perego
Keyword(s):  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Response Regulator ◽  
Specific Binding ◽  
Competence Development ◽  
Target Dna ◽  
Synergistic Regulation ◽  
Dna Promoters ◽  
Carboxy Terminal ◽  
Encoding Genes

ABSTRACT The 11 Rap proteins of Bacillus subtilis comprise a conserved family of tetratricopeptide (TPR)-containing regulatory proteins. Their activity is inhibited by specific Phr pentapeptides produced from the product of phr genes through an export-import maturation process. We found that one of the proteins, namely RapF, is involved in the regulation of competence to DNA transformation. The ComA response regulator and transcription factor for initiation of competence development is the target of RapF. Specific binding of RapF to the carboxy-terminal DNA-binding domain of ComA inhibits the response regulator's ability to bind its target DNA promoters. The PhrF C-terminal pentapeptide, QRGMI, inhibits RapF activity. The activity of RapF and PhrF in regulating competence development is analogous to the previously described activity of RapC and PhrC (L. J. Core and M. Perego, Mol. Microbiol. 49:1509-1522, 2003). In fact, the RapF and PhrF pair of proteins acts synergistically with RapC and PhrC in the overall regulation of the ComA transcription factor. Since the transcription of the RapC- and RapF-encoding genes is positively regulated by their own target ComA, an autoregulatory circuit must exist for the competence transcription factor in order to modulate its activity.

Redox-Dependent Dynamics in Heme-Bound Bacterial Iron Response Regulator (Irr) Protein

Biochemistry ◽  
2016 ◽  
Vol 55 (29) ◽  
pp. 4047-4054 ◽  
Author(s):  
Kazuo Kobayashi ◽  
Megumi Nakagaki ◽  
Haruto Ishikawa ◽  
Kazuhiro Iwai ◽  
Mark R. O’Brian ◽  
...  
Keyword(s):  
Response Regulator ◽  
Iron Response Regulator
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