Role of Two Novel Two-Component Regulatory Systems in Development and Phosphatase Expression in Myxococcus xanthus

ABSTRACT We have cloned a two-component regulatory system (phoR2-phoP2) of Myxococcus xanthus while searching for genes that encode proteins with phosphatase activity, where phoR2 encodes the histidine kinase and phoP2 encodes the response regulator. A second system, phoR3-phoP3, was identified and isolated by using phoP2 as a probe. These two systems are quite similar, sharing identities along the full-length proteins of 52% on the histidine kinases and 64% on the response regulators. The predicted structures of both kinases suggest that they are anchored to the membrane, with the sensor domains being located in the periplasmic space and the kinase domains in the cytoplasm. The response regulators (PhoP2 and PhoP3) exhibit a helix-loop-helix motif typical of DNA-binding proteins in the effector domains located in the C-terminal region. Studies on two single-deletion mutants and one double-deletion mutant have revealed that these systems are involved in development. Mutant fruiting bodies are not well packed, originating loose and flat aggregates where some myxospores do not reshape properly, and they remain as elongated cells. These systems are also involved in the expression of Mg-independent acid and neutral phosphatases, which are expressed during development. The neutral phosphatase gene is especially dependent on PhoP3. Neither PhoP2 nor PhoP3 regulates the expression of alkaline phosphatases and the pph1 gene.

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The Two-Component Regulatory System TCS08 Is Involved in Cellobiose Metabolism of Streptococcus pneumoniae R6

Journal of Bacteriology ◽

10.1128/jb.01170-06 ◽

2006 ◽

Vol 189 (4) ◽

pp. 1342-1350 ◽

Cited By ~ 46

Author(s):

Stuart J. McKessar ◽

Regine Hakenbeck

Keyword(s):

Streptococcus Pneumoniae ◽

Response Regulator ◽

Regulatory System ◽

Phosphotransferase System ◽

Two Component System ◽

Transcription Profiles ◽

Regulatory Systems ◽

Two Component ◽

Cognate Response Regulator ◽

Gram Positive Cocci

ABSTRACT The two-component system TCS08 is one of the regulatory systems that is important for virulence of Streptococcus pneumoniae. In order to investigate the TCS08 regulon, we have analyzed transcription profiles of mutants derived from S. pneumoniae R6 by microarray analysis. Since deletion mutants are often without a significant phenotype, we constructed a mutation in the histidine kinase HK08, T133P, in analogy to the phosphatase mutation T230P in the H box of the S. pneumoniae CiaH kinase described recently (D. Zähner, K. Kaminski, M. van der Linden, T. Mascher, M. Merai, and R. Hakenbeck, J. Mol. Microbiol. Biotechnol. 4:211-216, 2002). In addition, a deletion mutation was constructed in rr08, encoding the cognate response regulator. The most heavily suppressed genes in the hk08 mutant were spr0276 to spr0282, encoding a putative cellobiose phosphoenolpyruvate sugar phosphotransferase system (PTS). Whereas the R6 Smr parent strain and the Δrr08 mutant readily grew on cellobiose, the hk08 mutant and selected mutants with deletions in the PTS cluster did not, strongly suggesting that TCS08 is involved in the catabolism of cellobiose. Homologues of the TCS08 system were found in closely related streptococci and other gram-positive cocci. However, the genes spr0276 to spr0282, encoding the putative cellobiose PTS, represent a genomic island in S. pneumoniae and homologues were found in Streptococcus gordonii only, suggesting that this system might contribute to the pathogenicity potential of the pneumococcus.

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Progress Overview of Bacterial Two-Component Regulatory Systems as Potential Targets for Antimicrobial Chemotherapy

Antibiotics ◽

10.3390/antibiotics9100635 ◽

2020 ◽

Vol 9 (10) ◽

pp. 635

Author(s):

Hidetada Hirakawa ◽

Jun Kurushima ◽

Yusuke Hashimoto ◽

Haruyoshi Tomita

Keyword(s):

Drug Resistance ◽

Antimicrobial Chemotherapy ◽

Response Regulator ◽

Regulatory System ◽

Laboratory Strain ◽

Regulatory Systems ◽

Two Component ◽

Bacterial Genes ◽

Conventional Antibiotics ◽

External Stimuli

Bacteria adapt to changes in their environment using a mechanism known as the two-component regulatory system (TCS) (also called “two-component signal transduction system” or “two-component system”). It comprises a pair of at least two proteins, namely the sensor kinase and the response regulator. The former senses external stimuli while the latter alters the expression profile of bacterial genes for survival and adaptation. Although the first TCS was discovered and characterized in a non-pathogenic laboratory strain of Escherichia coli, it has been recognized that all bacteria, including pathogens, use this mechanism. Some TCSs are essential for cell growth and fitness, while others are associated with the induction of virulence and drug resistance/tolerance. Therefore, the TCS is proposed as a potential target for antimicrobial chemotherapy. This concept is based on the inhibition of bacterial growth with the substances acting like conventional antibiotics in some cases. Alternatively, TCS targeting may reduce the burden of bacterial virulence and drug resistance/tolerance, without causing cell death. Therefore, this approach may aid in the development of antimicrobial therapeutic strategies for refractory infections caused by multi-drug resistant (MDR) pathogens. Herein, we review the progress of TCS inhibitors based on natural and synthetic compounds.

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Identification of a Streptococcus pneumoniae Gene Locus Encoding Proteins of an ABC Phosphate Transporter and a Two-Component Regulatory System

Journal of Bacteriology ◽

10.1128/jb.181.4.1126-1133.1999 ◽

1999 ◽

Vol 181 (4) ◽

pp. 1126-1133 ◽

Cited By ~ 52

Author(s):

Rodger Novak ◽

Anje Cauwels ◽

Emmanuelle Charpentier ◽

Elaine Tuomanen

Keyword(s):

Response Regulator ◽

Regulatory System ◽

Phosphate Limitation ◽

Pho Regulon ◽

Loss Of Function ◽

Gene Encoding ◽

E Coli ◽

Two Component ◽

Pst System

ABSTRACT The Escherichia coli Pst system belongs to the family of ABC transporters. It is part of a phosphate (PHO) regulon which is regulated by extracellular phosphate. Under conditions of phosphate limitation, the response regulator PhoB is phosphorylated by the histidine kinase PhoR and binds to promoters that share a consensus PHO box. Under conditions of phosphate excess, PhoR, Pst, and PhoU downregulate the PHO regulon. Screening of a library of pneumococcal mutants with defects in exported proteins revealed a putative two-component regulatory system, PnpR-PnpS, and a downstream ABC transporter, similar to the Pst system in E. coli including a gene encoding a PhoU protein. Similar to E. coli, mutagenesis of the ATP-binding cassette gene, pstB, resulted in decreased uptake of phosphate. The effects of the loss of the pneumococcal Pst system extended to decreased transformation and lysis. Withdrawal of phosphate led to transformation deficiency in the parent strain R6x but not to penicillin tolerance, suggesting that reduced bacterial death was independent of phosphate. None of these phenotypes was observed in the pneumococcal loss-of-function mutantphoU. By using a lacZ reporter construct, it was demonstrated that expression of the two-component regulatory system PnpR-PnpS was not influenced by different concentrations of phosphate. These results suggest a more complex role of the Pst system in pneumococcal physiology than in that of E. coli.

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Mutations Affecting HVO_1357 or HVO_2248 Cause Hypermotility in Haloferax volcanii, Suggesting Roles in Motility Regulation

Genes ◽

10.3390/genes12010058 ◽

2020 ◽

Vol 12 (1) ◽

pp. 58

Author(s):

Michiyah Collins ◽

Simisola Afolayan ◽

Aime B. Igiraneza ◽

Heather Schiller ◽

Elise Krespan ◽

...

Keyword(s):

Histidine Kinase ◽

Response Regulator ◽

Regulatory System ◽

Haloferax Volcanii ◽

Adjacent Gene ◽

Transposon Insertion ◽

Regulatory Systems ◽

Two Component ◽

Motility Regulation ◽

Transposon Insertions

Motility regulation plays a key role in prokaryotic responses to environmental stimuli. Here, we used a motility screen and selection to isolate hypermotile Haloferax volcanii mutants from a transposon insertion library. Whole genome sequencing revealed that hypermotile mutants were predominantly affected in two genes that encode HVO_1357 and HVO_2248. Alterations of these genes comprised not only transposon insertions but also secondary genome alterations. HVO_1357 contains a domain that was previously identified in the regulation of bacteriorhodopsin transcription, as well as other domains frequently found in two-component regulatory systems. The genes adjacent to hvo_1357 encode a sensor box histidine kinase and a response regulator, key players of a two-component regulatory system. None of the homologues of HVO_2248 have been characterized, nor does it contain any of the assigned InterPro domains. However, in a significant number of Haloferax species, the adjacent gene codes for a chemotaxis receptor/transducer. Our results provide a foundation for characterizing the root causes underlying Hfx. volcanii hypermotility.

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Autophosphorylation and Dephosphorylation by Soluble Forms of the Nitrate-Responsive Sensors NarX and NarQ from Escherichia coli K-12

Journal of Bacteriology ◽

10.1128/jb.00092-08 ◽

2008 ◽

Vol 190 (11) ◽

pp. 3869-3876 ◽

Cited By ~ 25

Author(s):

Chris E. Noriega ◽

Radomir Schmidt ◽

Michael J. Gray ◽

Li-Ling Chen ◽

Valley Stewart

Keyword(s):

Escherichia Coli ◽

Rate Constant ◽

Response Regulator ◽

Response Regulators ◽

Amino Terminal ◽

Regulatory Systems ◽

Two Component ◽

Nitrite Nitrate ◽

Nitrate And Nitrite ◽

K 12

ABSTRACT NarX-NarL and NarQ-NarP are paralogous two-component regulatory systems that control Escherichia coli gene expression in response to the respiratory oxidants nitrate and nitrite. Nitrate stimulates the autophosphorylation rates of the NarX and NarQ sensors, which then phosphorylate the response regulators NarL and NarP to activate and repress target operon transcription. Here, we investigated both the autophosphorylation and dephosphorylation of soluble sensors in which the maltose binding protein (MBP) has replaced the amino-terminal transmembrane sensory domain. The apparent affinities (Km ) for ADP were similar for both proteins, about 2 μM, whereas the affinity of MBP-NarQ for ATP was lower, about 23 μM. At a saturating concentration of ATP, the rate constant of MBP-NarX autophosphorylation (about 0.5 × 10−4 s−1) was lower than that observed for MBP-NarQ (about 2.2 × 10−4 s−1). At a saturating concentration of ADP, the rate constant of dephosphorylation was higher than that of autophosphorylation, about 0.03 s−1 for MBP-NarX and about 0.01 s−1 for MBP-NarQ. For other studied sensors, the published affinities for ADP range from about 16 μM (KinA) to about 40 μM (NtrB). This suggests that only a small proportion of NarX and NarQ remain phosphorylated in the absence of nitrate, resulting in efficient response regulator dephosphorylation by the remaining unphosphorylated sensors.

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Activation of the Campylobacter jejuni FlgSR Two-Component System Is Linked to the Flagellar Export Apparatus

Journal of Bacteriology ◽

10.1128/jb.01689-08 ◽

2009 ◽

Vol 191 (8) ◽

pp. 2656-2667 ◽

Cited By ~ 44

Author(s):

Stephanie N. Joslin ◽

David R. Hendrixson

Keyword(s):

Gene Expression ◽

Campylobacter Jejuni ◽

Response Regulator ◽

Regulatory System ◽

Two Component System ◽

Regulatory Cascade ◽

Regulatory Systems ◽

Two Component ◽

Flagellar Protein ◽

Flagellar Genes

ABSTRACT Activation of σ54-dependent gene expression essential for formation of flagella in Campylobacter jejuni requires the components of the inner membrane-localized flagellar export apparatus and the FlgSR two-component regulatory system. In this study, we characterized the FlgS sensor kinase and how activation of the protein is linked to the flagellar export apparatus. We found that FlgS is localized to the C. jejuni cytoplasm and that His141 of FlgS is essential for autophosphorylation, phosphorelay to the cognate FlgR response regulator, motility, and expression of σ54-dependent flagellar genes. Mutants with incomplete flagellar export apparatuses produced wild-type levels of FlgS and FlgR, but they were defective for signaling through the FlgSR system. By using genetic approaches, we found that FlgSR activity is linked to and downstream of the flagellar export apparatus in a regulatory cascade that terminates in expression of σ54-dependent flagellar genes. By analyzing defined flhB and fliI mutants of C. jejuni that form flagellar export apparatuses that are secretion incompetent, we determined that formation of the apparatus is required to contribute to the signal sensed by FlgS to terminate in activation of expression of σ54-dependent flagellar genes. Considering that the flagellar export apparatuses of Escherichia coli and Salmonella species influence σ28-dependent flagellar gene expression, our work expands the signaling activity of the apparatuses to include σ54-dependent pathways of C. jejuni and possibly other motile bacteria. This study indicates that these apparatuses have broader functions beyond flagellar protein secretion, including activation of essential two-component regulatory systems required for expression of σ54-dependent flagellar genes.

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Polymyxin Resistance ofPseudomonas aeruginosa phoQMutants Is Dependent on Additional Two-Component Regulatory Systems

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02353-12 ◽

2013 ◽

Vol 57 (5) ◽

pp. 2204-2215 ◽

Cited By ~ 56

Author(s):

Alina D. Gutu ◽

Nicole Sgambati ◽

Pnina Strasbourger ◽

Mark K. Brannon ◽

Michael A. Jacobs ◽

...

Keyword(s):

Lipid A ◽

Regulatory System ◽

Content Type ◽

Regulatory Systems ◽

Clinical Resistance ◽

Component Systems ◽

Two Component ◽

Two Component Systems ◽

High Level

ABSTRACTPseudomonas aeruginosacan develop resistance to polymyxin as a consequence of mutations in the PhoPQ regulatory system, mediated by covalent lipid A modification. Transposon mutagenesis of a polymyxin-resistantphoQmutant defined 41 novel loci required for resistance, including two regulatory systems, ColRS and CprRS. Deletion of thecolRSgenes, individually or in tandem, abrogated the polymyxin resistance of a ΔphoQmutant, as did individual or tandem deletion ofcprRS. Individual deletion ofcolRorcolSin a ΔphoQmutant also suppressed 4-amino-l-arabinose addition to lipid A, consistent with the known role of this modification in polymyxin resistance. Surprisingly, tandem deletion ofcolRSorcprRSin the ΔphoQmutant or individual deletion ofcprRorcprSfailed to suppress 4-amino-l-arabinose addition to lipid A, indicating that this modification alone is not sufficient for PhoPQ-mediated polymyxin resistance inP. aeruginosa. Episomal expression ofcolRSorcprRSin tandem or ofcprRindividually complemented the Pm resistance phenotype in the ΔphoQmutant, while episomal expression ofcolR,colS, orcprSindividually did not. Highly polymyxin-resistantphoQmutants ofP. aeruginosaisolated from polymyxin-treated cystic fibrosis patients harbored mutant alleles ofcolRSandcprS; when expressed in a ΔphoQbackground, these mutant alleles enhanced polymyxin resistance. These results define ColRS and CprRS as two-component systems regulating polymyxin resistance inP. aeruginosa, indicate that addition of 4-amino-l-arabinose to lipid A is not the only PhoPQ-regulated biochemical mechanism required for resistance, and demonstrate thatcolRSandcprSmutations can contribute to high-level clinical resistance.

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