scholarly journals Genetic Studies of mrp, a Locus Essential for Cellular Aggregation and Sporulation of Myxococcus xanthus

2001 ◽  
Vol 183 (16) ◽  
pp. 4786-4795 ◽  
Author(s):  
Hong Sun ◽  
Wenyuan Shi
Keyword(s):  
Developmental Process ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Regulatory Protein ◽  
Phosphorylation Site ◽  
Receptor Protein ◽  
Insertion Mutant ◽  
Developmental Gene Expression ◽  
Putative Phosphorylation Site ◽  
Cellular Aggregation

ABSTRACT Under starvation conditions, Myxococcus xanthusundergoes a complex developmental process which includes cellular aggregation and sporulation. A transposon insertion mutant (the Tn5-Ω280 mutant) with defects in both aggregation and sporulation was analyzed in this study. The Tn5-Ω280 mutant was found to have a disrupted NtrC-like response regulator designated Myxococcusregulatory protein B (mrpB). Further sequencing analyses revealed a histidine kinase homolog (mrpA) immediately upstream of mrpB and a cyclic AMP receptor protein-like transcriptional regulator (mrpC) downstream ofmrpB. In-frame deletion analyses revealed that both themrpB and mrpC genes were required for cellular aggregation and sporulation but that only mrpAwas required for sporulation only. Site-specific mutagenesis of the putative phosphorylation site of MrpB, D58, showed that a D58A mutation caused defects in both aggregation and sporulation but that a D58E mutation resulted in only a sporulation defect. Further genetic and molecular analyses with reporter genes and reverse transcription-PCR indicated that mrpA and mrpB are cotranscribed but that mrpC is transcribed independently and that all of these genes are developmentally regulated. In addition, MrpB is essential for transcription of mrpC and MrpC regulates its own transcription. These data indicate that Mrp proteins are important components required for M. xanthusdevelopment. The complicated interaction between Mrp proteins may play an important role in regulating developmental gene expression inM. xanthus.

scholarly journals Biochemical and Genetic Evidence for Participation of DevR in a Phosphorelay Signal Transduction Pathway Essential for Heterocyst Maturation in Nostoc punctiforme ATCC 29133

1999 ◽  
Vol 181 (14) ◽  
pp. 4430-4434 ◽  
Author(s):  
Kari D. Hagen ◽  
John C. Meeks
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Signal Transduction Pathway ◽  
Site Directed Mutagenesis ◽  
Single Amino Acid ◽  
Insertion Mutant ◽  
Nostoc Punctiforme ◽  
Putative Phosphorylation Site

ABSTRACT In a test of the hypothesis that DevR is a response regulator protein that functions in a phosphorelay signal transduction system involved in heterocyst development in Nostoc punctiformeATCC 29133, purified affinity-tagged DevR was shown to be phosphorylated in vitro by the noncognate sensor kinase EnvZ. Site-directed mutagenesis was used to generate N. punctiforme mutants with single amino acid substitutions at the putative phosphorylation site of DevR. These mutants exhibited a Fox− phenotype like the original devRinsertion mutant UCD 311, consistent with a phosphotransferase role for DevR.

scholarly journals Multistep Phosphorelay Proteins Transmit Oxidative Stress Signals to the Fission Yeast Stress-activated Protein Kinase

2000 ◽  
Vol 11 (4) ◽  
pp. 1169-1181 ◽  
Author(s):  
Aaron Ngocky Nguyen ◽  
Albert Lee ◽  
Warren Place ◽  
Kazuhiro Shiozaki
Keyword(s):  
Oxidative Stress ◽  
Protein Kinase ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Bzip Transcription Factor ◽  
Specific Gene ◽  
Putative Phosphorylation Site ◽  
Stress Signals ◽  
Cognate Response Regulator ◽  
Novel Protein

In response to oxidative stress, eukaryotic cells induce transcription of genes required for detoxification of oxidants. Here we present evidence that oxidative stress stimuli are transmitted by a multistep phosphorelay system to the Spc1/Sty1 stress-activated protein kinase in the fission yeastSchizosaccharomyces pombe. The fission yeastmpr1+gene encodes a novel protein with a histidine-containing phosphotransfer domain homologous to the budding yeast Ypd1. Spc1 activation upon oxidative stress is severely impaired in the Δmpr1 mutant as well as in thempr1HQ strain, in which the putative phosphorylation site Mpr1-His221 is substituted with glutamine. In response to oxidative stress, Mpr1 binds to the Mcs4 response regulator that functions upstream of the Spc1 cascade, suggesting that Mcs4 is a cognate response regulator for Mpr1. Unexpectedly, when exposed to hydrogen peroxide, Δmpr1 cells can induce the catalase gene ctt1+, one of the transcriptional targets of the Spc1 pathway, and survive oxidative stress in the absence of significant Spc1 activation. We have found that Pap1, a bZIP transcription factor homologous to human c-Jun, can mediate induction of ctt1+expression upon oxidative stress independently of the Spc1 stress-activated protein kinase. These studies show that oxidative stress stimuli are transmitted by multiple pathways to induce specific gene expression.

scholarly journals Combinatorial Regulation by a Novel Arrangement of FruA and MrpC2 Transcription Factors during Myxococcus xanthus Development

2009 ◽  
Vol 191 (8) ◽  
pp. 2753-2763 ◽  
Author(s):  
Sheenu Mittal ◽  
Lee Kroos
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Promoter Region ◽  
Developmental Process ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Control Cell ◽  
Cooperative Binding ◽  
Regulatory Sequence

ABSTRACT Myxococcus xanthus is a gram-negative soil bacterium that undergoes multicellular development upon nutrient limitation. Intercellular signals control cell movements and regulate gene expression during the developmental process. C-signal is a short-range signal essential for aggregation and sporulation. C-signaling regulates the fmgA gene by a novel mechanism involving cooperative binding of the response regulator FruA and the transcription factor/antitoxin MrpC2. Here, we demonstrate that regulation of the C-signal-dependent fmgBC operon is under similar combinatorial control by FruA and MrpC2, but the arrangement of binding sites is different than in the fmgA promoter region. MrpC2 was shown to bind to a crucial cis-regulatory sequence in the fmgBC promoter region. FruA was required for MrpC and/or MrpC2 to associate with the fmgBC promoter region in vivo, and expression of an fmgB-lacZ fusion was abolished in a fruA mutant. Recombinant FruA was shown to bind to an essential regulatory sequence located slightly downstream of the MrpC2-binding site in the fmgBC promoter region. Full-length FruA, but not its C-terminal DNA-binding domain, enhanced the formation of complexes with fmgBC promoter region DNA, when combined with MrpC2. This effect was nearly abolished with fmgBC DNA fragments having a mutation in either the MrpC2- or FruA-binding site, indicating that binding of both proteins to DNA is important for enhancement of complex formation. These results are similar to those observed for fmgA, where FruA and MrpC2 bind cooperatively upstream of the promoter, except that in the fmgA promoter region the FruA-binding site is located slightly upstream of the MrpC2-binding site. Cooperative binding of FruA and MrpC2 appears to be a conserved mechanism of gene regulation that allows a flexible arrangement of binding sites and coordinates multiple signaling pathways.

scholarly journals A Conserved Two-Component Signal Transduction System Controls the Response to Phosphate Starvation in Bifidobacterium breve UCC2003

2012 ◽  
Vol 78 (15) ◽  
pp. 5258-5269 ◽  
Author(s):  
Pablo Alvarez-Martin ◽  
Matilde Fernández ◽  
Mary O'Connell-Motherway ◽  
Kerry Joan O'Connell ◽  
Nicolas Sauvageot ◽  
...  
Keyword(s):  
Response Regulator ◽  
Regulatory Protein ◽  
Gc Content ◽  
Regulatory System ◽  
Bioinformatic Analysis ◽  
Insertion Mutant ◽  
Recognition Sequence ◽  
Content Type ◽  
Bifidobacterium Breve ◽  
Two Component

ABSTRACTThis work reports on the identification and molecular characterization of the two-component regulatory system (2CRS) PhoRP, which controls the response to inorganic phosphate (Pi) starvation inBifidobacterium breveUCC2003. The response regulator PhoP was shown to bind to the promoter region ofpstSCAB, specifying a predicted Pitransporter system, as well as that ofphoU, which encodes a putative Pi-responsive regulatory protein. This interaction is assumed to cause transcriptional modulation under conditions of Pilimitation. Our data suggest that thephoRPgenes are subject to positive autoregulation and, together withpstSCABand presumablyphoU, represent the complete regulon controlled by thephoRP-encoded 2CRS inB. breveUCC2003. Determination of the minimal PhoP binding region combined with bioinformatic analysis revealed the probable recognition sequence of PhoP, designated here as the PHO box, which together withphoRPis conserved among many high-GC-content Gram-positive bacteria. The importance of thephoRP2CRS in the response ofB. breveto Pistarvation conditions was confirmed by analysis of aB. brevephoPinsertion mutant which exhibited decreased growth under phosphate-limiting conditions compared to its parent strain UCC2003.

scholarly journals Genome-Wide Identification of Genes Necessary for Biofilm Formation by Nosocomial Pathogen Stenotrophomonas maltophilia Reveals that Orphan Response Regulator FsnR Is a Critical Modulator

2014 ◽  
Vol 81 (4) ◽  
pp. 1200-1209 ◽  
Author(s):  
Xiu-Min Kang ◽  
Fang-Fang Wang ◽  
Huan Zhang ◽  
Qi Zhang ◽  
Wei Qian
Keyword(s):  
Cell Motility ◽  
Biofilm Formation ◽  
Stenotrophomonas Maltophilia ◽  
Response Regulator ◽  
Critical Role ◽  
Regulatory Protein ◽  
Lipid Synthesis ◽  
Cell Aggregation ◽  
Insertion Mutant ◽  
Content Type

ABSTRACTStenotrophomonas maltophiliais a Gram-negative bacterial pathogen of increasing concern to human health. Most clinical isolates ofS. maltophiliaefficiently form biofilms on biotic and abiotic surfaces, making this bacterium resistant to a number of antibiotic treatments and therefore difficult to eliminate. To date, very few studies have investigated the molecular and regulatory mechanisms responsible forS. maltophiliabiofilm formation. Here we constructed a random transposon insertion mutant library ofS. maltophiliaATCC 13637 and screened 14,028 clones. A total of 46 nonredundant genes were identified. Mutants of these genes exhibited marked changes in biofilm formation, suggesting that multiple physiological pathways, including extracellular polysaccharide production, purine synthesis, transportation, and peptide and lipid synthesis, are involved in bacterial cell aggregation. Of these genes, 20 putatively contributed to flagellar biosynthesis, indicating a critical role for cell motility inS. maltophiliabiofilm formation. Genetic and biochemical evidence demonstrated that an orphan response regulator, FsnR, activated transcription of at least two flagellum-associated operons by directly binding to their promoters. This regulatory protein plays a fundamental role in controlling flagellar assembly, cell motility, and biofilm formation. These results provide a genetic basis to systematically study biofilm formation ofS. maltophilia.

scholarly journals Analyses of mrp Genes during Myxococcus xanthus Development

2001 ◽  
Vol 183 (23) ◽  
pp. 6733-6739 ◽  
Author(s):  
Hong Sun ◽  
Wenyuan Shi
Keyword(s):  
Histidine Kinase ◽  
Response Regulator ◽  
Genetic Locus ◽  
Myxococcus Xanthus ◽  
Receptor Protein ◽  
Transcription Activator ◽  
Fruiting Body Formation ◽  
Developmental Genes ◽  
Biochemical Analyses ◽  
Starvation Conditions

ABSTRACT Myxococcus xanthus is a gram-negative soil bacterium that undergoes development under starvation conditions. Our previous study identified a new genetic locus, mrp, which is required for both fruiting body formation and sporulation. The locus encodes two transcripts: mrpAB, which consists of a histidine kinase and an NtrC-like response regulator, andmrpC, a cyclic AMP receptor protein family transcription activator. In this study, we used genetic and biochemical analyses to investigate the possible interactions between themrp genes and other known developmental genes and events. These studies show that the mrp genes possibly function after A-signaling and (p)ppGpp but before C-signaling and that they regulate various early and late developmental genes and events.

scholarly journals Regulation of Motility Behavior in Myxococcus xanthus May Require an Extracytoplasmic-Function Sigma Factor

1998 ◽  
Vol 180 (21) ◽  
pp. 5668-5675 ◽  
Author(s):  
Mandy J. Ward ◽  
Helen Lew ◽  
Anke Treuner-Lange ◽  
David R. Zusman
Keyword(s):  
Life Cycle ◽  
Sigma Factor ◽  
Response Regulator ◽  
Myxococcus Xanthus ◽  
Complex Life Cycle ◽  
Insertion Mutant ◽  
Insertion Mutation ◽  
Ecf Sigma Factor ◽  
Developmental Conditions ◽  
Motility Behavior

ABSTRACT Using interaction trap technology, we identified a putative extracytoplasmic-function (ECF) sigma factor (RpoE1) inMyxococcus xanthus, a bacterium which has a complex life cycle that includes fruiting body formation. The first domain of the response regulator protein FrzZ, a component of the Frz signal transduction system, was used as bait. Although the RpoE1 protein displayed no interactions with control proteins presented as bait, a weak interaction with a second M. xanthus response regulator (AsgA) was observed. While the specificity of the FrzZ-RpoE1 interaction therefore remains speculative, cloning and sequencing of the region surrounding rpoE1 localized it to a position downstream of the frzZ gene. A potential promoter site for binding of an ECF sigma factor was identified upstream ofrpoE1, suggesting the gene may be autoregulated. However, primer extension studies suggested that transcription ofrpoE1 occurs under both vegetative and developmental conditions from a ς70-like promoter. Dot blot analysis of RNA preparations confirmed the low-level, constitutive expression ofrpoE1 during both stages of the life cycle. Analysis of an insertion mutant also indicated a role for RpoE1 under both vegetative and developmental conditions, since swarming was reduced on nutrient-rich agar and developmental aggregation was effected under starvation conditions, especially at high cell densities. An insertion mutation introduced into the gene directly downstream ofrpoE1 (orf5) did not result in either swarming or developmental aggregation defects, even though the gene is transcribed as part of the same operon. Therefore, we propose that this new ECF sigma factor could play a role in the transcriptional regulation of genes involved in motility behavior during both stages of the complex M. xanthus life cycle.

scholarly journals Molecular Characterization and Phylogenetic Analysis of MADS-Box Gene VroAGL11 Associated with Stenospermocarpic Seedlessness in Muscadine Grapes

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 232
Author(s):  
M Atikur Rahman ◽  
Subramani P Balasubramani ◽  
Sheikh M Basha
Keyword(s):  
Phylogenetic Analysis ◽  
Phosphorylation Site ◽  
Orthologous Gene ◽  
Mads Box ◽  
Vitis Species ◽  
Vitis Rotundifolia ◽  
Seed Content ◽  
Putative Phosphorylation Site ◽  
Mads Box Gene ◽  
Muscadine Grapes

Reduced expression of MADS-box gene AGAMOUS-LIKE11 (VviAGL11) is responsible for stenospermocarpic seedlessness in bunch grapes. This study is aimed to characterize the VviAGL11 orthologous gene (VroAGL11) in native muscadine grapes (Vitis rotundifolia) at the molecular level and analyze its divergence from other plants. The VroAGL11 transcripts were found in all muscadine cultivars tested and highly expressed in berries while barely detectable in leaves. RT-PCR and sequencing of predicted ORFs from diverse grape species showed that AGL11 transcripts were conservatively spliced. The encoded VroAGL11 protein contains highly conserved MADS-MEF2-like domain, MADS domain, K box, putative phosphorylation site and two sumoylation motifs. The muscadine VroAGL11 proteins are almost identical (99%) to that of seeded bunch cultivar, Chardonnay, except in one amino acid (A79G), but differs from mutant protein of seedless bunch grape, Sultanina, in two amino acids, R197L and T210A. Phylogenetic analysis showed that AGL11 gene of muscadine and other Vitis species formed a separate clade than that of other eudicots and monocots. Muscadine grape cultivar “Jane Bell” containing the highest percentage of seed content in berry (7.2% of berry weight) had the highest VroAGL11 expression, but almost none to nominal expression in seedless cultivars Fry Seedless (muscadine) and Reliance Seedless (bunch). These findings suggest that VroAGL11 gene controls the seed morphogenesis in muscadine grapes like in bunch grape and can be manipulated to induce stenospermocarpic seedlessness using gene editing technology.

scholarly journals act Operon Control of Developmental Gene Expression in Myxococcus xanthus

2002 ◽  
Vol 184 (4) ◽  
pp. 1172-1179 ◽  
Author(s):  
Thomas M. A. Gronewold ◽  
Dale Kaiser
Keyword(s):  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
The Other ◽  
Loss Of Function ◽  
Wild Type ◽  
Developmental Gene ◽  
Developmental Gene Expression ◽  
Mutant Strains ◽  
Genes Encoding ◽  
Signal Production

ABSTRACT Cell-bound C-signal guides the building of a fruiting body and triggers the differentiation of myxospores. Earlier work has shown that transcription of the csgA gene, which encodes the C-signal, is directed by four genes of the act operon. To see how expression of the genes encoding components of the aggregation and sporulation processes depends on C-signaling, mutants with loss-of-function mutations in each of the act genes were investigated. These mutations were found to have no effect on genes that are normally expressed up to 3 h into development and are C-signal independent. Neither the time of first expression nor the rate of expression increase was changed in actA, actB, actC, or actD mutant strains. Also, there was no effect on A-signal production, which normally starts before 3 h. By contrast, the null act mutants have striking defects in C-signal production. These mutations changed the expression of four gene reporters that are related to aggregation and sporulation and are expressed at 6 h or later in development. The actA and actB null mutations substantially decreased the expression of all these reporters. The other act null mutations caused either premature expression to wild-type levels (actC) or delayed expression (actD), which ultimately rose to wild-type levels. The pattern of effects on these reporters shows how the C-signal differentially regulates the steps that together build a fruiting body and differentiate spores within it.

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