scholarly journals A central role for the transcriptional regulator VtlR in small RNA-mediated gene regulation in Agrobacterium tumefaciens

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
James A. Budnick ◽  
Lauren M. Sheehan ◽  
Miranda. J. Ginder ◽  
Kevin C. Failor ◽  
Julia. M. Perkowski ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Sinorhizobium Meliloti ◽  
Transcriptional Regulators ◽  
Close Relative ◽  
Environmental Niche ◽  
Crown Gall Disease ◽  
Plant Symbiont ◽  
Small Regulatory Rna ◽  
Host Microbe Interactions ◽  
And Function

Abstract LysR-type transcriptional regulators (LTTRs) are the most common type of transcriptional regulators in prokaryotes and function by altering gene expression in response to environmental stimuli. In the class Alphaproteobacteria, a conserved LTTR named VtlR is critical to the establishment of host-microbe interactions. In the mammalian pathogen Brucella abortus, VtlR is required for full virulence in a mouse model of infection, and VtlR activates the expression of abcR2, which encodes a small regulatory RNA (sRNA). In the plant symbiont Sinorhizobium meliloti, the ortholog of VtlR, named LsrB, is involved in the symbiosis of the bacterium with alfalfa. Agrobacterium tumefaciens is a close relative of both B. abortus and S. meliloti, and this bacterium is the causative agent of crown gall disease in plants. In the present study, we demonstrate that VtlR is involved in the ability of A. tumefaciens to grow appropriately in artificial medium, and an A. tumefaciens vtlR deletion strain is defective in motility, biofilm formation, and tumorigenesis of potato discs. RNA-sequencing analyses revealed that more than 250 genes are dysregulated in the ∆vtlR strain, and importantly, VtlR directly controls the expression of three sRNAs in A. tumefaciens. Taken together, these data support a model in which VtlR indirectly regulates hundreds of genes via manipulation of sRNA pathways in A. tumefaciens, and moreover, while the VtlR/LsrB protein is present and structurally conserved in many members of the Alphaproteobacteria, the VtlR/LsrB regulatory circuitry has diverged in order to accommodate the unique environmental niche of each organism.

scholarly journals Neurons interact with the microbiome: an evolutionary-informed perspective

Neuroforum ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christoph Giez ◽  
Alexander Klimovich ◽  
Thomas C. G. Bosch
Keyword(s):  
Nervous System ◽  
Neural Circuits ◽  
Current Knowledge ◽  
System Development ◽  
Nervous System Development ◽  
Comprehensive Understanding ◽  
Strategic Model ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
And Function

Abstract Animals have evolved within the framework of microbes and are constantly exposed to diverse microbiota. Microbes colonize most, if not all, animal epithelia and influence the activity of many organs, including the nervous system. Therefore, any consideration on nervous system development and function in the absence of the recognition of microbes will be incomplete. Here, we review the current knowledge on the nervous systems of Hydra and its role in the host–microbiome communication. We show that recent advances in molecular and imaging methods are allowing a comprehensive understanding of the capacity of such a seemingly simple nervous system in the context of the metaorganism. We propose that the development, function and evolution of neural circuits must be considered in the context of host–microbe interactions and present Hydra as a strategic model system with great basic and translational relevance for neuroscience.

scholarly journals Structure and antimicrobial activity of NCR169, a nodule-specific cysteine-rich peptide of Medicago truncatula

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noriyoshi Isozumi ◽  
Yuya Masubuchi ◽  
Tomohiro Imamura ◽  
Masashi Mori ◽  
Hironori Koga ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Medicago Truncatula ◽  
Mechanism Of Action ◽  
Disulfide Bonds ◽  
Sinorhizobium Meliloti ◽  
Bound State ◽  
Disulfide Linkage ◽  
Model Legume ◽  
Nmr Structures ◽  
And Function

AbstractA model legume, Medicago truncatula, has over 600 nodule-specific cysteine-rich (NCR) peptides required for symbiosis with rhizobia. Among them, NCR169, an essential factor for establishing symbiosis, has four cysteine residues that are indispensable for its function. However, knowledge of NCR169 structure and mechanism of action is still lacking. In this study, we solved two NMR structures of NCR169 caused by different disulfide linkage patterns. We show that both structures have a consensus C-terminal β-sheet attached to an extended N-terminal region with dissimilar features; one moves widely, whereas the other is relatively stapled. We further revealed that the disulfide bonds of NCR169 contribute to its structural stability and solubility. Regarding the function, one of the NCR169 oxidized forms could bind to negatively charged bacterial phospholipids. Furthermore, the positively charged lysine-rich region of NCR169 may be responsible for its antimicrobial activity against Escherichia coli and Sinorhizobium meliloti. This active region was disordered even in the phospholipid bound state, suggesting that the disordered conformation of this region is key to its function. Morphological observations suggested the mechanism of action of NCR169 on bacteria. The present study on NCR169 provides new insights into the structure and function of NCR peptides.

scholarly journals Parallel changes in gut microbiome composition and function in parallel local adaptation and speciation

2019 ◽  
Author(s):  
Diana J. Rennison ◽  
Seth M. Rudman ◽  
Dolph Schluter
Keyword(s):  
Microbial Communities ◽  
Local Adaptation ◽  
Biotic Interactions ◽  
Ecological Speciation ◽  
Microbiome Composition ◽  
Interacting Species ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
And Function ◽  
Host Evolution

AbstractThe processes of local adaptation and ecological speciation are often strongly shaped by biotic interactions such as competition and predation. One of the strongest lines of evidence that biotic interactions drive evolution comes from repeated divergence of lineages in association with repeated changes in the community of interacting species. Yet, relatively little is known about the repeatability of changes in gut microbial communities and their role in adaptation and divergence of host populations in nature. Here we utilize three cases of rapid, parallel adaptation and speciation in freshwater threespine stickleback to test for parallel changes in associated gut microbiomes. We find that features of the gut microbial communities have shifted repeatedly in the same direction in association with parallel divergence and speciation of stickleback hosts. These results suggest that changes to gut microbiomes can occur rapidly and predictably in conjunction with host evolution, and that host-microbe interactions might play an important role in host adaptation and diversification.

scholarly journals Intraspecific variation in immune gene expression and heritable symbiont density

2021 ◽  
Vol 17 (4) ◽  
pp. e1009552
Author(s):  
Holly L. Nichols ◽  
Elliott B. Goldstein ◽  
Omid Saleh Ziabari ◽  
Benjamin J. Parker
Keyword(s):  
Gene Expression ◽  
Acyrthosiphon Pisum ◽  
Aphid Species ◽  
F1 Hybrids ◽  
Immune Gene ◽  
Immune Genes ◽  
Immune Mechanisms ◽  
Immune Gene Expression ◽  
Host Microbe Interactions ◽  
And Function

Host genetic variation plays an important role in the structure and function of heritable microbial communities. Recent studies have shown that insects use immune mechanisms to regulate heritable symbionts. Here we test the hypothesis that variation in symbiont density among hosts is linked to intraspecific differences in the immune response to harboring symbionts. We show that pea aphids (Acyrthosiphon pisum) harboring the bacterial endosymbiontRegiella insecticola(but not all other species of symbionts) downregulate expression of key immune genes. We then functionally link immune expression with symbiont density using RNAi. The pea aphid species complex is comprised of multiple reproductively-isolated host plant-adapted populations. These ‘biotypes’ have distinct patterns of symbiont infections: for example, aphids from theTrifoliumbiotype are strongly associated withRegiella. Using RNAseq, we compare patterns of gene expression in response toRegiellain aphid genotypes from multiple biotypes, and we show thatTrifoliumaphids experience no downregulation of immune gene expression while hostingRegiellaand harbor symbionts at lower densities. Using F1 hybrids between two biotypes, we find that symbiont density and immune gene expression are both intermediate in hybrids. We propose that in this system,Regiellasymbionts are suppressing aphid immune mechanisms to increase their density, but that some hosts have adapted to prevent immune suppression in order to control symbiont numbers. This work therefore suggests that antagonistic coevolution can play a role in host-microbe interactions even when symbionts are transmitted vertically and provide a clear benefit to their hosts. The specific immune mechanisms that we find are downregulated in the presence ofRegiellahave been previously shown to combat pathogens in aphids, and thus this work also highlights the immune system’s complex dual role in interacting with both beneficial and harmful microbes.

Perception of Agrobacterium tumefaciens flagellin by FLS2XL confers resistance to crown gall disease

Nature Plants ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Ursula Fürst ◽  
Yi Zeng ◽  
Markus Albert ◽  
Anna Kristina Witte ◽  
Judith Fliegmann ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Crown Gall ◽  
Crown Gall Disease

scholarly journals Characteristics of the LrhA subfamily of transcriptional regulators from Sinorhizobium meliloti

2008 ◽  
Vol 40 (2) ◽  
pp. 166-173
Author(s):  
Mingsheng Qi ◽  
Li Luo ◽  
Haiping Cheng ◽  
Jiabi Zhu ◽  
Guanqiao Yu
Keyword(s):  
Sinorhizobium Meliloti ◽  
Transcriptional Regulators

scholarly journals Two Agrobacterium tumefaciens CheW Proteins Are Incorporated into One Chemosensory Pathway with Different Efficiencies

2018 ◽  
Vol 31 (4) ◽  
pp. 460-470 ◽  
Author(s):  
Zhiwei Huang ◽  
Qingxuan Zhou ◽  
Pan Sun ◽  
Jing Yang ◽  
Minliang Guo
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Histidine Kinase ◽  
Promoter Activity ◽  
Crown Gall Tumor ◽  
Signaling Complex ◽  
Chemosensory Pathway ◽  
Dicotyledonous Plants ◽  
The Difference ◽  
Coupling Protein ◽  
And Function

Agrobacterium tumefaciens is the agent that causes crown gall tumor disease on more than 140 species of dicotyledonous plants. Chemotaxis of A. tumefaciens toward the wound sites of the host plant is the first step to recognize the host. CheW is a coupling protein that bridges the histidine kinase CheA and the chemoreceptors to form the chemotaxis core signaling complex and plays a crucial role in the assembly and function of the large chemosensory array. Unlike all previously reported chemotaxis systems, A. tumefaciens has only one major che operon but two cheW homologs (atu2075 as cheW1 and atu2617 as cheW2) on unlinked loci. The in-frame deletion of either cheW gene significantly affects A. tumefaciens chemotaxis but does not abolish the chemotaxis, unless both cheW genes were deleted. The effect of cheW2 deletion on the chemotaxis is more severe than that of cheW1 deletion. Either CheW can interact with CheA and couple it to the cell poles. The promoter activity of cheW2 is always higher than that of cheW1 under all of the tested conditions. When two cheW genes were adjusted to the same expression level by using the identical promoter, the difference between the effects of two CheW proteins on the chemotaxis still existed. Therefore, we envision that both the different molecular ratio of two CheW proteins in cell and the different affinities of two CheW proteins with CheA and chemoreceptors result in the efficiency difference of two CheW proteins in functioning in the large chemosensory array.

scholarly journals Agrobacterium tumefaciens ExoR represses succinoglycan biosynthesis and is required for biofilm formation and motility

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2670-2681 ◽  
Author(s):  
Amelia D. Tomlinson ◽  
Bronwyn Ramey-Hartung ◽  
Travis W. Day ◽  
Peter M. Merritt ◽  
Clay Fuqua
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Plant Tissues ◽  
Flagellar Motility ◽  
Regulatory Pathway ◽  
Flow Conditions ◽  
Two Component System ◽  
Form Complex ◽  
Abiotic Surfaces

The ubiquitous plant pathogen Agrobacterium tumefaciens attaches efficiently to plant tissues and abiotic surfaces and can form complex biofilms. A genetic screen for mutants unable to form biofilms on PVC identified disruptions in a homologue of the exoR gene. ExoR is a predicted periplasmic protein, originally identified in Sinorhizobium meliloti, but widely conserved among alphaproteobacteria. Disruptions in the A. tumefaciens exoR gene result in severely compromised attachment to abiotic surfaces under static and flow conditions, and to plant tissues. These mutants are hypermucoid due to elevated production of the exopolysaccharide succinoglycan, via derepression of the exo genes that direct succinoglycan synthesis. In addition, exoR mutants have lost flagellar motility, do not synthesize detectable flagellin and are diminished in flagellar gene expression. The attachment deficiency is, however, complex and not solely attributable to succinoglycan overproduction or motility disruption. A. tumefaciens ExoR can function independently of the ChvG–ChvI two component system, implicated in ExoR-dependent regulation in S. meliloti. Mutations that suppress the exoR motility defect suggest a branched regulatory pathway controlling succinoglycan synthesis, motility and biofilm formation.

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