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Advances in Genetics 2022Several species of the genus represent unique bacterial pathogens able to genetically transform plants, by transferring and integrating a segment of their own DNA... (Review)
Review
Several species of the genus represent unique bacterial pathogens able to genetically transform plants, by transferring and integrating a segment of their own DNA (T-DNA, transferred DNA) in their host genome. Whereas in nature this process results in uncontrolled growth of the infected plant cells (tumors), this capability of has been widely used as a crucial tool to generate transgenic plants, for research and biotechnology. The virulence of relies on a series of virulence genes, mostly encoded on a large plasmid (Ti-plasmid, tumor inducing plasmid), involved in the different steps of the DNA transfer to the host cell genome: activation of bacterial virulence, synthesis and export of the T-DNA and its associated proteins, intracellular trafficking of the T-DNA and effector proteins in the host cell, and integration of the T-DNA in the host genomic DNA. Multiple interactions between these bacterial encoded proteins and host factors occur during the infection process, which determine the outcome of the infection. Here, we review our current knowledge of the mechanisms by which bacterial and plant factors control virulence and host plant susceptibility.
Topics: Virulence; Agrobacterium tumefaciens; Plants, Genetically Modified; Plasmids; Bacteria; Bacterial Proteins; Virulence Factors
PubMed: 37283660
DOI: 10.1016/bs.adgen.2022.08.001 -
Journal of Experimental Botany Jun 2023CRISPR/Cas9 genome editing and Agrobacterium tumefaciens-mediated genetic transformation are widely-used plant biotechnology tools derived from bacterial...
CRISPR/Cas9 genome editing and Agrobacterium tumefaciens-mediated genetic transformation are widely-used plant biotechnology tools derived from bacterial immunity-related systems, each involving DNA modification. The Cas9 endonuclease introduces DNA double-strand breaks (DSBs), and the A. tumefaciens T-DNA is released by the VirD2 endonuclease assisted by VirDl and attached by VirE2, transferred to the plant nucleus and integrated into the genome. Here, we explored the potential for synergy between the two systems and found that Cas9 and three virulence (Vir) proteins achieve precise genome editing via the homology directed repair (HDR) pathway in tobacco and rice plants. Compared with Cas9T (Cas9, VirD1, VirE2) and CvD (Cas9-VirD2) systems, the HDR frequencies of a foreign GFPm gene in the CvDT system (Cas9-VirD2, VirD1, VirE2) increased 52-fold and 22-fold, respectively. Further optimization of the CvDT process with a donor linker (CvDTL) achieved a remarkable increase in the efficiency of HDR-mediated genome editing. Additionally, the HDR efficiency of the three rice endogenous genes ACETOLACTATE SYNTHASE (ALS), PHYTOENE DESATURASE (PDS), and NITROGEN TRANSPORTER 1.1 B (NRT1.1B) increased 24-, 32- and 16-fold, respectively, in the CvDTL system, compared with corresponding Cas9TL (Cas9T process with a donor linker). Our results suggest that collaboration between CRISPR/Cas9 and Agrobacterium-mediated genetic transformation can make great progress towards highly efficient and precise genome editing via the HDR pathway.
Topics: Gene Editing; CRISPR-Cas Systems; Agrobacterium tumefaciens; Virulence; DNA
PubMed: 36919203
DOI: 10.1093/jxb/erad096 -
Journal of Bacteriology Jan 2021The type VI secretion system (T6SS) is a widespread antibacterial weapon capable of secreting multiple effectors for inhibition of competitor cells. Most of the...
The type VI secretion system (T6SS) is a widespread antibacterial weapon capable of secreting multiple effectors for inhibition of competitor cells. Most of the effectors in the system share the same purpose of target intoxication, but the rationale for maintaining various types of effectors in a species is not well studied. In this study, we showed that a peptidoglycan amidase effector in , Tae, cleaves d-Ala--diaminopimelic acid (mDAP) and d-Glu bonds in peptidoglycan and is able to suppress the growth of recipient cells. The growth suppression was effective only under the condition in which cells are actively growing. In contrast, the Tde DNase effectors in the strain possessed a dominant killing effect under carbon starvation. Microscopic analysis showed that Tde triggers cell elongation and DNA degradation, while Tae causes cell enlargement without DNA damage in recipient cells. In a rich medium, harboring only functional Tae was able to maintain competitiveness among and its own sibling cells. Growth suppression and the competitive advantage of were abrogated when recipient cells produced the Tae-specific immunity protein Tai. Given that Tae is highly conserved among strains, the combination of Tae and Tde effectors could allow to better compete with various competitors by increasing its survival during changing environmental conditions. The T6SS encodes multiple effectors with diverse functions, but little is known about the biological significance of harboring such a repertoire of effectors. We reported that the T6SS antibacterial activity of the plant pathogen can be enhanced under carbon starvation or when recipient cell wall peptidoglycan is disturbed. This led to a newly discovered role for the T6SS peptidoglycan amidase Tae effector in providing a growth advantage dependent on the growth status of the target cell. This is in contrast to the Tde DNase effectors that are dominant during carbon starvation. Our study suggests that combining Tae and other effectors could allow to increase its competitiveness among changing environmental conditions.
Topics: Agrobacterium tumefaciens; Anti-Bacterial Agents; Bacterial Proteins; Cell Wall; Deoxyribonucleases; Escherichia coli; Peptidoglycan; Type VI Secretion Systems
PubMed: 33168638
DOI: 10.1128/JB.00490-20 -
Current Opinion in Microbiology Dec 2009Agrobacterium tumefaciens is a plant pathogen that transfers a segment of its own DNA into host plants to cause Crown Gall disease. The infection process requires... (Review)
Review
Agrobacterium tumefaciens is a plant pathogen that transfers a segment of its own DNA into host plants to cause Crown Gall disease. The infection process requires intimate contact between the infecting bacteria and the host tissue. A. tumefaciens attaches efficiently to plant tissues and to abiotic surfaces, and can establish complex biofilms at colonization sites. The dominant mode of attachment is via a single pole in contact with the surface. Several different appendages, adhesins and adhesives play roles during attachment, and foster the transition from free-swimming to sessile growth. This polar surface interaction reflects a more fundamental cellular asymmetry in A. tumefaciens that influences and is congruent with its attached lifestyle.
Topics: Adhesins, Bacterial; Agrobacterium tumefaciens; Bacterial Adhesion; Biofilms; Gene Expression Regulation, Bacterial; Models, Biological; Organelles; Plant Diseases
PubMed: 19879182
DOI: 10.1016/j.mib.2009.09.014 -
Scientific Reports Mar 2017Antimonite [Sb(III)]-oxidizing bacteria can transform the toxic Sb(III) into the less toxic antimonate [Sb(V)]. Recently, the cytoplasmic Sb(III)-oxidase AnoA and the...
Antimonite [Sb(III)]-oxidizing bacteria can transform the toxic Sb(III) into the less toxic antimonate [Sb(V)]. Recently, the cytoplasmic Sb(III)-oxidase AnoA and the periplasmic arsenite [As(III)] oxidase AioAB were shown to responsible for bacterial Sb(III) oxidation, however, disruption of each gene only partially decreased Sb(III) oxidation efficiency. This study showed that in Agrobacterium tumefaciens GW4, Sb(III) induced cellular HO content and HO degradation gene katA. Gene knock-out/complementation of katA, anoA, aioA and anoA/aioA and Sb(III) oxidation and growth experiments showed that katA, anoA and aioA were essential for Sb(III) oxidation and resistance and katA was also essential for HO resistance. Furthermore, linear correlations were observed between cellular HO and Sb(V) content in vivo and chemical HO and Sb(V) content in vitro (R = 0.93 and 0.94, respectively). These results indicate that besides the biotic factors, the cellular HO induced by Sb(III) also catalyzes bacterial Sb(III) oxidation as an abiotic oxidant. The data reveal a novel mechanism that bacterial Sb(III) oxidation is associated with abiotic (cellular HO) and biotic (AnoA and AioAB) factors and Sb(III) oxidation process consumes cellular HO which contributes to microbial detoxification of both Sb(III) and cellular HO.
Topics: Agrobacterium tumefaciens; Antimony; Gene Knockout Techniques; Genetic Complementation Test; Hydrogen Peroxide; Oxidation-Reduction; Peroxidases
PubMed: 28252030
DOI: 10.1038/srep43225 -
MBio May 2021The growth pole ring (GPR) protein forms a hexameric ring at the growth pole (GP) that is essential for polar growth. GPR is large (2,115 amino acids) and contains...
The growth pole ring (GPR) protein forms a hexameric ring at the growth pole (GP) that is essential for polar growth. GPR is large (2,115 amino acids) and contains 1,700 amino acids of continuous α-helices. To dissect potential GPR functional domains, we created deletions of regions with similarity to human apolipoprotein A-IV (396 amino acids), itself composed of α-helical domains. We also tested deletions of the GPR C terminus. Deletions were inducibly expressed as green fluorescent protein (GFP) fusion proteins and tested for merodiploid interference with wild-type (WT) GPR function, for partial function in cells lacking GPR, and for formation of paired fluorescent foci (indicative of hexameric rings) at the GP. Deletion of domains similar to human apolipoprotein A-IV in GPR caused defects in cell morphology when expressed in to WT GPR and provided only partial complementation to cells lacking GPR. -specific domains A-IV-1 and A-IV-4 contain predicted coiled coil (CC) regions of 21 amino acids; deletion of CC regions produced severe defects in cell morphology in the interference assay. Mutants that produced the most severe effects on cell shape also failed to form paired polar foci. Modeling of A-IV-1 and A-IV-4 reveals significant similarity to the solved structure of human apolipoprotein A-IV. GPR C-terminal deletions profoundly blocked complementation. Finally, peptidoglycan (PG) synthesis is abnormally localized circumferentially in cells lacking GPR. The results support the hypothesis that GPR plays essential roles as an organizing center for membrane and PG synthesis during polar growth. Bacterial growth and division are extensively studied in model systems (, , and ) that grow by dispersed insertion of new cell wall material along the length of the cell. An alternative growth mode-polar growth-is used by some and species. The latter phylum includes the family , in which many species, including , exhibit polar growth. Current research aims to identify growth pole (GP) factors. The growth pole ring (GPR) protein is essential for polar growth and forms a striking hexameric ring structure at the GP. GPR is long (2,115 amino acids), and little is known about regions essential for structure or function. Genetic analyses demonstrate that the C terminus of GPR, and two internal regions with homology to human apolipoproteins (that sequester lipids), are essential for GPR function and localization to the GP. We hypothesize that GPR is an organizing center for membrane and cell wall synthesis during polar growth.
Topics: Agrobacterium tumefaciens; Apolipoproteins; Cell Cycle Proteins; Cell Division; Cell Polarity; Cell Wall; Green Fluorescent Proteins
PubMed: 34006657
DOI: 10.1128/mBio.00764-21 -
Environmental Microbiology Jan 2018Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity... (Review)
Review
Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity in shaping the ecological and evolutionary dynamics of these facultative pathogens are incompletely understood. Agrobacterium tumefaciens, the causative agent for crown gall disease of plants has proven a productive model for many aspects of interactions between pathogens and their hosts and with other microbes. In this review, we highlight how this past work provides valuable context for the use of this system to examine how heterogeneity and transitions between disease and non-disease environments influence the ecology and evolution of facultative pathogens. We focus on several features common among facultative pathogens, such as the physiological remodelling required to colonize hosts from environmental reservoirs and the consequences of competition with host and non-host associated microbiota. In addition, we discuss how the life history of facultative pathogens likely often results in ecological tradeoffs associated with performance in disease and non-disease environments. These pathogens may therefore have different competitive dynamics in disease and non-disease environments and are subject to shifting selective pressures that can result in pathoadaptation or the within-host spread of avirulent phenotypes.
Topics: Agrobacterium tumefaciens; Biofilms; Biological Evolution; Ecology; Plant Tumors; Plants; Plasmids
PubMed: 29105274
DOI: 10.1111/1462-2920.13976 -
Phytopathology Oct 2015Agrobacterium species are soilborne gram-negative bacteria exhibiting predominantly a saprophytic lifestyle. Only a few of these species are capable of parasitic growth... (Review)
Review
Agrobacterium species are soilborne gram-negative bacteria exhibiting predominantly a saprophytic lifestyle. Only a few of these species are capable of parasitic growth on plants, causing either hairy root or crown gall diseases. The core of the infection strategy of pathogenic Agrobacteria is a genetic transformation of the host cell, via stable integration into the host genome of a DNA fragment called T-DNA. This genetic transformation results in oncogenic reprogramming of the host to the benefit of the pathogen. This unique ability of interkingdom DNA transfer was largely used as a tool for genetic engineering. Thus, the artificial host range of Agrobacterium is continuously expanding and includes plant and nonplant organisms. The increasing availability of genomic tools encouraged genome-wide surveys of T-DNA tagged libraries, and the pattern of T-DNA integration in eukaryotic genomes was studied. Therefore, data have been collected in numerous laboratories to attain a better understanding of T-DNA integration mechanisms and potential biases. This review focuses on the intranuclear mechanisms necessary for proper targeting and stable expression of Agrobacterium oncogenic T-DNA in the host cell. More specifically, the role of genome features and the putative involvement of host's transcriptional machinery in relation to the T-DNA integration and effects on gene expression are discussed. Also, the mechanisms underlying T-DNA integration into specific genome compartments is reviewed, and a theoretical model for T-DNA intranuclear targeting is presented.
Topics: Agrobacterium tumefaciens; Cell Nucleus; DNA, Bacterial; Gene Transfer Techniques; Host-Pathogen Interactions; Plant Diseases; Plants
PubMed: 26151736
DOI: 10.1094/PHYTO-12-14-0380-RVW -
Current Topics in Microbiology and... 2018The Agrobacterium tumefaciens VirB/VirD4 translocation machine is a member of a superfamily of translocators designated as type IV secretion systems (T4SSs) that... (Review)
Review
The Agrobacterium tumefaciens VirB/VirD4 translocation machine is a member of a superfamily of translocators designated as type IV secretion systems (T4SSs) that function in many species of gram-negative and gram-positive bacteria. T4SSs evolved from ancestral conjugation systems for specialized purposes relating to bacterial colonization or infection. A. tumefaciens employs the VirB/VirD4 T4SS to deliver oncogenic DNA (T-DNA) and effector proteins to plant cells, causing the tumorous disease called crown gall. This T4SS elaborates both a cell-envelope-spanning channel and an extracellular pilus for establishing target cell contacts. Recent mechanistic and structural studies of the VirB/VirD4 T4SS and related conjugation systems in Escherichia coli have defined T4SS architectures, bases for substrate recruitment, the translocation route for DNA substrates, and steps in the pilus biogenesis pathway. In this review, we provide a brief history of A. tumefaciens VirB/VirD4 T4SS from its discovery in the 1980s to its current status as a paradigm for the T4SS superfamily. We discuss key advancements in defining VirB/VirD4 T4SS function and structure, and we highlight the power of in vivo mutational analyses and chimeric systems for identifying mechanistic themes and specialized adaptations of this fascinating nanomachine.
Topics: Agrobacterium tumefaciens; Bacterial Proteins; Mutagenesis; Recombinant Fusion Proteins; Type IV Secretion Systems
PubMed: 29808338
DOI: 10.1007/82_2018_94 -
Microbial Genomics Nov 2020is an efficient tool for creating transgenic host plants. The first step in the genetic transformation process involves chemotaxis, which is crucial to the survival of...
is an efficient tool for creating transgenic host plants. The first step in the genetic transformation process involves chemotaxis, which is crucial to the survival of in changeable, harsh and even contaminated soil environments. However, a systematic study of its chemotactic signalling pathway is still lacking. In this study, the distribution and classification of chemotactic genes in the model C58 and 21 other strains were annotated. Local blast was used for comparative genomics, and hmmer was used for predicting protein domains. Chemotactic phenotypes for knockout mutants of ternary signalling complexes in C58 were evaluated using a swim agar plate. A major cluster, in which chemotaxis genes were consistently organized as MCP (methyl-accepting chemotaxis protein), CheS, CheY1, CheA, CheR, CheB, CheY2 and CheD, was found in , but two coupling CheW proteins were located outside the '' cluster. In the ternary signalling complexes, the absence of MCP atu0514 significantly impaired chemotaxis, and the absence of CheA (atu0517) or the deletion of both CheWs abolished chemotaxis. A total of 465 MCPs were found in the 22 strains, and the cytoplasmic domains of these MCPs were composed of 38 heptad repeats. A high homology was observed between the chemotactic systems of the 22 strains with individual differences in the gene and receptor protein distributions, possibly related to their ecological niches. This preliminary study demonstrates the chemotactic system of , and provides some reference for sensing and chemotaxis to exogenous signals.
Topics: Agrobacterium tumefaciens; Amino Acid Sequence; Chemotaxis; Computer Simulation; Genome, Bacterial; Methyl-Accepting Chemotaxis Proteins; Phylogeny; Plants; Sequence Alignment; Signal Transduction
PubMed: 33118922
DOI: 10.1099/mgen.0.000460