scholarly journals Small RNAs OmrA and OmrB promote class III flagellar gene expression by inhibiting the synthesis of anti-Sigma factor FlgM

RNA Biology ◽  
2020 ◽  
Vol 17 (6) ◽  
pp. 872-880
Author(s):  
Cédric Romilly ◽  
Mirthe Hoekzema ◽  
Erik Holmqvist ◽  
E. Gerhart H. Wagner
Keyword(s):  
Gene Expression ◽  
Sigma Factor ◽  
Small Rnas ◽  
Flagellar Gene ◽  
Class Iii

scholarly journals Role of Integration Host Factor in the Transcriptional Activation of Flagellar Gene Expression in Caulobacter crescentus

2005 ◽  
Vol 187 (3) ◽  
pp. 949-960 ◽  
Author(s):  
Rachel E. Muir ◽  
James W. Gober
Keyword(s):  
Gene Expression ◽  
Caulobacter Crescentus ◽  
Consensus Sequence ◽  
Integration Host Factor ◽  
Host Factor ◽  
Flagellar Gene ◽  
Class Iii ◽  
Mild Defect ◽  
Flagellar Genes ◽  
Class Iv

ABSTRACT In the Caulobacter crescentus predivisional cell, class III and IV flagellar genes, encoding the extracytoplasmic components of the flagellum, are transcribed in the nascent swarmer compartment. This asymmetric expression pattern is attributable to the compartmentalized activity of the σ54-dependent transcriptional activator FlbD. Additionally, these temporally transcribed flagellar promoters possess a consensus sequence for the DNA-binding protein integration host factor (IHF), located between the upstream FlbD binding site and the promoter sequences. Here, we deleted the C. crescentus gene encoding the β-subunit of the IHF, ihfB (himD), and examined the effect on flagellar gene expression. The ΔihfB strain exhibited a mild defect in cell morphology and impaired motility. Using flagellar promoter reporter fusions, we observed that expression levels of a subset of class III flagellar promoters were decreased by the loss of IHF. However, one of these promoters, fliK-lacZ, exhibited a wild-type cell cycle-regulated pattern of expression in the absence of IHF. Thus, IHF is required for maximal transcription of several late flagellar genes. The ΔihfB strain was found to express significantly reduced amounts of the class IV flagellin, FljL, as a consequence of reduced transcriptional activity. Our results indicate that the motility defect exhibited by the ΔihfB strain is most likely attributable to its failure to accumulate the class IV-encoded 27-kDa flagellin subunit, FljL.

scholarly journals FliZ Is a Posttranslational Activator of FlhD4C2-Dependent Flagellar Gene Expression

2008 ◽  
Vol 190 (14) ◽  
pp. 4979-4988 ◽  
Author(s):  
Supreet Saini ◽  
Jonathon D. Brown ◽  
Phillip D. Aldridge ◽  
Christopher V. Rao
Keyword(s):  
Gene Expression ◽  
Sigma Factor ◽  
Flagellar Gene ◽  
Critical Aspect ◽  
Swarming Motility ◽  
Flagellar Biosynthesis ◽  
Serovar Typhimurium ◽  
Flagellar Assembly

ABSTRACT Flagellar assembly proceeds in a sequential manner, beginning at the base and concluding with the filament. A critical aspect of assembly is that gene expression is coupled to assembly. When cells transition from a nonflagellated to a flagellated state, gene expression is sequential, reflecting the manner in which the flagellum is made. A key mechanism for establishing this temporal hierarchy is the σ28-FlgM checkpoint, which couples the expression of late flagellar (Pclass3) genes to the completion of the hook-basal body. In this work, we investigated the role of FliZ in coupling middle flagellar (Pclass2) gene expression to assembly in Salmonella enterica serovar Typhimurium. We demonstrate that FliZ is an FlhD4C2-dependent activator of Pclass2/middle gene expression. Our results suggest that FliZ regulates the concentration of FlhD4C2 posttranslationally. We also demonstrate that FliZ functions independently of the flagellum-specific sigma factor σ28 and the filament-cap chaperone/FlhD4C2 inhibitor FliT. Furthermore, we show that the previously described ability of σ28 to activate Pclass2/middle gene expression is, in fact, due to FliZ, as both are expressed from the same overlapping Pclass2 and Pclass3 promoters at the fliAZY locus. We conclude by discussing the role of FliZ regulation with respect to flagellar biosynthesis based on our characterization of gene expression and FliZ's role in swimming and swarming motility.

scholarly journals Negative Control of Flagellum Synthesis in Pseudomonas aeruginosa Is Modulated by the Alternative Sigma Factor AlgT (AlgU)

1999 ◽  
Vol 181 (23) ◽  
pp. 7401-7404 ◽  
Author(s):  
Edward S. Garrett ◽  
Demetra Perlegas ◽  
Daniel J. Wozniak
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Sigma Factor ◽  
Negative Control ◽  
Alternative Sigma Factor ◽  
Flagellar Gene

ABSTRACT Many respiratory isolates of Pseudomonas aeruginosafrom cystic fibrosis patients are mucoid (alginate producing) yet lack flagella. It was hypothesized that an alginate regulator inhibits flagellar gene expression. Mutations in algB,algR, and algT resulted in nonmucoid derivatives, yet algT mutants expressed flagella. AlgT-dependent control of flagellum synthesis occurred through inhibition of fliC but not rpoN transcription.

scholarly journals Themes and Variations: Regulation of RpoN-Dependent Flagellar Genes across Diverse Bacterial Species

Scientifica ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Jennifer Tsang ◽  
Timothy R. Hoover
Keyword(s):  
Gene Expression ◽  
Campylobacter Jejuni ◽  
Sigma Factor ◽  
Caulobacter Crescentus ◽  
Bacterial Species ◽  
Alternative Sigma Factor ◽  
Flagellar Gene ◽  
Complex Process ◽  
Flagellar Biogenesis ◽  
Flagellar Genes

Flagellar biogenesis in bacteria is a complex process in which the transcription of dozens of structural and regulatory genes is coordinated with the assembly of the flagellum. Although the overall process of flagellar biogenesis is conserved among bacteria, the mechanisms used to regulate flagellar gene expression vary greatly among different bacterial species. Many bacteria use the alternative sigma factorσ54(also known as RpoN) to transcribe specific sets of flagellar genes. These bacteria include members of the Epsilonproteobacteria (e.g.,Helicobacter pyloriandCampylobacter jejuni), Gammaproteobacteria (e.g.,VibrioandPseudomonasspecies), and Alphaproteobacteria (e.g.,Caulobacter crescentus). This review characterizes the flagellar transcriptional hierarchies in these bacteria and examines what is known about how flagellar gene regulation is linked with other processes including growth phase, quorum sensing, and host colonization.

scholarly journals The secreted endoribonuclease ENDU-2 from the soma protects germline immortality in C. elegans

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjing Qi ◽  
Erika D. V. Gromoff ◽  
Fan Xu ◽  
Qian Zhao ◽  
Wei Yang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cell ◽  
Small Rnas ◽  
C Elegans ◽  
Cleavage Activity ◽  
Response To Temperature ◽  
Multicellular Organisms ◽  
Cell Immortality ◽  
Mature Mrnas ◽  
Endoribonuclease Activity

AbstractMulticellular organisms coordinate tissue specific responses to environmental information via both cell-autonomous and non-autonomous mechanisms. In addition to secreted ligands, recent reports implicated release of small RNAs in regulating gene expression across tissue boundaries. Here, we show that the conserved poly-U specific endoribonuclease ENDU-2 in C. elegans is secreted from the soma and taken-up by the germline to ensure germline immortality at elevated temperature. ENDU-2 binds to mature mRNAs and negatively regulates mRNA abundance both in the soma and the germline. While ENDU-2 promotes RNA decay in the soma directly via its endoribonuclease activity, ENDU-2 prevents misexpression of soma-specific genes in the germline and preserves germline immortality independent of its RNA-cleavage activity. In summary, our results suggest that the secreted RNase ENDU-2 regulates gene expression across tissue boundaries in response to temperature alterations and contributes to maintenance of stem cell immortality, probably via retaining a stem cell specific program of gene expression.

scholarly journals Concerted genomic and epigenomic changes accompany stabilization of Arabidopsis allopolyploids

2021 ◽  
Vol 5 (10) ◽  
pp. 1382-1393
Author(s):  
Xinyu Jiang ◽  
Qingxin Song ◽  
Wenxue Ye ◽  
Z. Jeffrey Chen
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Structural Variation ◽  
Self Incompatibility ◽  
Polyploid Evolution ◽  
Genomic Variations ◽  
Conserved Gene ◽  
Arabidopsis Suecica ◽  
Affect Gene Expression

AbstractDuring evolution successful allopolyploids must overcome ‘genome shock’ between hybridizing species but the underlying process remains elusive. Here, we report concerted genomic and epigenomic changes in resynthesized and natural Arabidopsis suecica (TTAA) allotetraploids derived from Arabidopsisthaliana (TT) and Arabidopsisarenosa (AA). A. suecica shows conserved gene synteny and content with more gene family gain and loss in the A and T subgenomes than respective progenitors, although A. arenosa-derived subgenome has more structural variation and transposon distributions than A. thaliana-derived subgenome. These balanced genomic variations are accompanied by pervasive convergent and concerted changes in DNA methylation and gene expression among allotetraploids. The A subgenome is hypomethylated rapidly from F1 to resynthesized allotetraploids and convergently to the T-subgenome level in natural A. suecica, despite many other methylated loci being inherited from F1 to all allotetraploids. These changes in DNA methylation, including small RNAs, in allotetraploids may affect gene expression and phenotypic variation, including flowering, silencing of self-incompatibility and upregulation of meiosis- and mitosis-related genes. In conclusion, concerted genomic and epigenomic changes may improve stability and adaptation during polyploid evolution.

XIPOU 2 is a potential regulator of Spemann's Organizer

Development ◽  
1997 ◽  
Vol 124 (6) ◽  
pp. 1179-1189 ◽  
Author(s):  
S.E. Witta ◽  
S.M. Sato
Keyword(s):  
Gene Expression ◽  
Wnt Pathway ◽  
Marginal Zone ◽  
Branchial Arch ◽  
Class Iii ◽  
Domain Family ◽  
Potent Inducer ◽  
Pou Domain ◽  
Spemann's Organizer ◽  
Dorsal Mesoderm

XIPOU 2, a member of the class III POU-domain family, is expressed initially at mid-blastula transition (MBT) and during gastrulation in the entire marginal zone mesoderm, including Spemann's Organizer (the Organizer). To identify potential targets of XIPOU 2, the interaction of XIPOU 2 with other genes co-expressed in the Organizer was examined by microinjecting XIPOU 2's mRNA into the lineage of cells that contributes to the Organizer, head mesenchyme and prechordal plate. XIPOU 2 suppresses the expression of a number of dorsal mesoderm-specific genes, including gsc, Xlim-1, Xotx2, noggin and chordin, but not Xnot. As a consequence of the suppression of dorsal mesoderm gene expression, bone morphogenetic factor-4 (Bmp-4), a potent inducer of ventral mesoderm, is activated in the Organizer. Gsc is a potential target of XIPOU 2. XIPOU 2 is capable of binding a class III POU protein binding site (CATTAAT) that is located within the gsc promoter, in the activin-inducible (distal) element. Furthermore, XIPOU 2 suppresses the activation of the gsc promoter by activin signaling. At the neurula and tailbud stages, dorsoanterior structures are affected: embryos displayed micropthalmia and the loss of the first branchial arch, as detected by the expression of pax-6, Xotx2 and en-2. By examining events downstream from the Wnt and chordin pathways, we determined that XIPOU 2, when overexpressed, acts specifically in the Organizer, downstream from GSK-3beta of the Wnt pathway and upstream from chordin. The interference in dorsalizing events caused by XIPOU 2 was rescued by chordin. Thus, in addition to its direct neuralizing ability, in a different context, XIPOU 2 has the potential to antagonize dorsalizing events in the Organizer.

Regulation of mouse CYP1A1 gene expression by dioxin: requirement of two cis-acting elements during induction

1989 ◽  
Vol 9 (6) ◽  
pp. 2378-2386
Author(s):  
L A Neuhold ◽  
Y Shirayoshi ◽  
K Ozato ◽  
J E Jones ◽  
D W Nebert
Keyword(s):  
Gene Expression ◽  
Simian Virus 40 ◽  
Class Ii ◽  
Simian Virus ◽  
Class I ◽  
Ah Receptor ◽  
Class Iii ◽  
Cis Acting ◽  
Cyp1a1 Gene ◽  
Sv40 Dna

The mouse cytochrome P1450 (CYP1A1) gene is responsible for the metabolism of numerous carcinogens and toxic chemicals. Induction by the environmental contaminant tetrachlorodibenzo-p-dioxin (TCDD) requires a functional aromatic hydrocarbon (Ah) receptor. We examined the 5'-flanking region of the CYP1A1 gene in mouse hepatoma Hepa-1 wild-type cells and a mutant line having a defect in chromatin binding of the TCDD-receptor complex. We identified two cis-acting elements (distal, -1071 to -901 region; proximal, -245 to -50 region) required for constitutive and TCDD-inducible CYP1A1 gene expression. Three classes of DNA-protein complexes binding to the distal element were identified: class I, found only in the presence of TCDD and a functional Ah receptor, that was heat labile and not competed against by simian virus 40 (SV40) early promoter DNA; class II, consisting of at least three constitutive complexes that were heat stable and bound to SV40 DNA; and class III, composed of at least three constitutive complexes that were thermolabile and were not competed against by SV40 DNA. Essential contacts for these proteins were centered at -993 to -990 for the class I complex, -987, -986, or both for the class II complexes, and -938 to -927 for the class III complexes. The proximal element was absolutely essential for both constitutive and TCDD-inducible CYP1A1 gene expression, and at least two constitutive complexes bound to this region. These data are consistent with the proximal element that binds proteins being necessary but not sufficient for inducible gene expression; interaction of these proteins with those at the distal element was found to be required for full CYP1A1 induction by TCDD.

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