Will you let me use your nucleus? How Agrobacterium gets its T-DNA expressed in the host plant cellThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 333-345 ◽  
Author(s):  
Benoît Lacroix ◽  
Jianxiong Li ◽  
Tzvi Tzfira ◽  
Vitaly Citovsky
Keyword(s):  
Nuclear Import ◽  
Effector Proteins ◽  
Host Genome ◽  
Host Proteins ◽  
T Complex ◽  
Host Cytoplasm ◽  
Host Cell Cytoplasm ◽  
A Cell ◽  
Host Nucleus ◽  
Selection Of

Agrobacterium is the only known bacterium capable of natural DNA transfer into a eukaryotic host. The genes transferred to host plants are contained on a T-DNA (transferred DNA) molecule, the transfer of which begins with its translocation, along with several effector proteins, from the bacterial cell to the host-cell cytoplasm. In the host cytoplasm, the T-complex is formed from a single-stranded copy of the T-DNA (T-strand) associated with several bacterial and host proteins and it is imported into the host nucleus via interactions with the host nuclear import machinery. Once inside the nucleus, the T-complex is most likely directed to the host genome by associating with histones. Finally, the chromatin-associated T-complex is uncoated from its escorting proteins prior to the conversion of the T-strand to a double-stranded form and its integration into the host genome.

The nuclear pore complex, nuclear transport, and apoptosisThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 279-286 ◽  
Author(s):  
Birthe Fahrenkrog
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Morphological Changes ◽  
Nuclear Transport ◽  
Nuclear Pore ◽  
Simple Fact ◽  
Cell Death Program ◽  
A Cell ◽  
Cellular Compartments ◽  
Selection Of

The nuclear pore complex (NPC) is the sole gateway between the nucleus and the cytoplasm of interphase eukaryotic cells, and it mediates all trafficking between these 2 cellular compartments. As such, the NPC and nuclear transport play central roles in translocating death signals from the cell membrane to the nucleus where they initiate biochemical and morphological changes occurring during apoptosis. Recent findings suggest that the correlation between the NPC, nuclear transport, and apoptosis goes beyond the simple fact that NPCs mediate nuclear transport of key players involved in the cell death program. In this context, the accessibility of key regulators of apoptosis appears to be highly modulated by nuclear transport (e.g., impaired nuclear import might be an apoptotic trigger). In this review, recent findings concerning the unexpected tight link between NPCs, nuclear transport, and apoptosis will be presented and critically discussed.

Nuclear import of spliceosomal snRNPsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 367-376 ◽  
Author(s):  
Christiane Rollenhagen ◽  
Nelly Panté
Keyword(s):  
Cell Nucleus ◽  
Nuclear Import ◽  
Current Knowledge ◽  
Protein Complexes ◽  
Special Issue ◽  
A Cell ◽  
Rna Maturation ◽  
Small Nuclear Ribonucleoproteins ◽  
Selection Of

Uridine-rich small nuclear ribonucleoproteins (U snRNPs) are the building units of the spliceosome. These RNA and protein complexes assemble in the cytoplasm. After proper assembly and RNA maturation, mature U snRNPs are imported into the cell nucleus, where they take part in the splicing process. In this paper we review the current knowledge of how U snRNPs enter the nucleus.

scholarly journals Agrobacterium-delivered VirE2 interacts with host nucleoporin CG1 to facilitate the nuclear import of VirE2-coated T complex

2020 ◽  
Vol 117 (42) ◽  
pp. 26389-26397 ◽  
Author(s):  
Xiaoyang Li ◽  
Qinghua Yang ◽  
Ling Peng ◽  
Haitao Tu ◽  
Lan-Ying Lee ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Transformation Process ◽  
Nuclear Pore ◽  
Natural Setting ◽  
Dependent Manner ◽  
Crown Gall Disease ◽  
T Complex ◽  
Nucleoprotein Complex ◽  
Importin Α ◽  
Host Nucleus

Agrobacterium tumefaciensis the causal agent of crown gall disease. The bacterium is capable of transferring a segment of single-stranded DNA (ssDNA) into recipient cells during the transformation process, and it has been widely used as a genetic modification tool for plants and nonplant organisms. Transferred DNA (T-DNA) has been proposed to be escorted by two virulence proteins, VirD2 and VirE2, as a nucleoprotein complex (T-complex) that targets the host nucleus. However, it is not clear how such a proposed large DNA–protein complex is delivered through the host nuclear pore in a natural setting. Here, we studied the natural nuclear import of theAgrobacterium-delivered ssDNA-binding protein VirE2 inside plant cells by using a split-GFP approach with a newly constructed T-DNA–free strain. Our results demonstrate that VirE2 is targeted into the host nucleus in a VirD2- and T-DNA–dependent manner. In contrast with VirD2 that binds to plant importin α for nuclear import, VirE2 directly interacts with the host nuclear pore complex component nucleoporin CG1 to facilitate its nuclear uptake and the transformation process. Our data suggest a cooperative nuclear import model in which T-DNA is guided to the host nuclear pore by VirD2 and passes through the pore with the assistance of interactions between VirE2 and host nucleoporin CG1. We hypothesize that this large linear nucleoprotein complex (T-complex) is targeted to the nucleus by a “head” guide from the VirD2–importin interaction and into the nucleus by a lateral assistance from the VirE2–nucleoporin interaction.

Combination of ribosome and phage display for fast selection of high affinity VHH antibody fragments

2019 ◽  
pp. 27-33
Author(s):  
YuE Kravchenko ◽  
SV Ivanov ◽  
DS Kravchenko ◽  
EI Frolova ◽  
SP Chumakov
Keyword(s):  
Phage Display ◽  
Selection Procedure ◽  
Free System ◽  
Phage Displays ◽  
High Affinity ◽  
Binding Domains ◽  
A Cell ◽  
Vhh Antibodies ◽  
Efficiency Of Selection ◽  
Selection Of

Selection of antibodies using phage display involves the preliminary cloning of the repertoire of sequences encoding antigen-binding domains into phagemid, which is considered the bottleneck of the method, limiting the resulting diversity of libraries and leading to the loss of poorly represented variants before the start of the selection procedure. Selection in cell-free conditions using a ribosomal display is devoid from this drawback, however is highly sensitive to PCR artifacts and the RNase contamination. The aim of the study was to test the efficiency of a combination of both methods, including pre-selection in a cell-free system to enrich the source library, followed by cloning and final selection using phage display. This approach may eliminate the shortcomings of each method and increase the efficiency of selection. For selection, alpaca VHH antibody sequences suitable for building an immune library were used due to the lack of VL domains. Analysis of immune libraries from the genes of the VH3, VHH3 and VH4 families showed that the VHH antibodies share in the VH3 and VH4 gene groups is insignificant, and selection from the combined library is less effective than from the VHH3 family of sequences. We found that the combination of ribosomal and phage displays leads to a higher enrichment of high-affinity fragments and avoids the loss of the original diversity during cloning. The combined method allowed us to obtain a greater number of different high-affinity sequences, and all the tested VHH fragments were able to specifically recognize the target, including the total protein extracts of cell cultures.

scholarly journals Immobilization of fish chromatophores for use as a micro-biosensor for biological toxins

2003 ◽  
Vol 57 (12) ◽  
pp. 605-610 ◽  
Author(s):  
Ljiljana Mojovic ◽  
Goran Jovanovic
Keyword(s):  
Cell Attachment ◽  
Cell Immobilization ◽  
Betta Splendens ◽  
Microbial Pathogens ◽  
Fish Cell ◽  
First Order Kinetics ◽  
Microcarrier Bead ◽  
Color Response ◽  
A Cell ◽  
Selection Of

Chromatophores isolated from the Siamese fighting fish, Betta splendens represent a class of living cells that provide a vivid color response to microbial pathogens and environmental toxins. The selection of the most appropriate microcarrier and the development of the optimal technique for the chromatophore immobilization in order to enable directed transport of the sensor cells throughout microchannels of the biosensor, as well to preserve the cell survival and its functionality was studied. Microcarriers derived from glass, polystyrene and gelatin (collagen) were tested as substrates for chromatophore attachement. Gelatin microcarriers were found to be the most suitable, due to high attachment efficiency (95% of attached cells), preservation of the cell viability and enhanced cell sensitivity. The optimum conditions for fish cell immobilization on collagen microcarriers were determined based on the cell-to-microcarrier bead ratio and the pH of the solution. The rate of cell attachment to the gelatin microcarrier followed first-order kinetics. Pretreatment of the gelatin beads with fibronectin, known as a cell attachment-promoting agent, resulted in a 10% higher attachment rate constant (k).

Understanding Cytoskeletal Dynamics During the Plant Immune Response

2018 ◽  
Vol 56 (1) ◽  
pp. 513-533 ◽  
Author(s):  
Jiejie Li ◽  
Christopher J. Staiger
Keyword(s):  
Immune Response ◽  
Cell Biology ◽  
Defense Mechanism ◽  
Current Knowledge ◽  
Effector Proteins ◽  
Actin Binding ◽  
Mechanical Stimuli ◽  
Dynamic Framework ◽  
Host Cytoplasm ◽  
Cytoskeletal Dynamics

The plant cytoskeleton is a dynamic framework of cytoplasmic filaments that rearranges as the needs of the cell change during growth and development. Incessant turnover mechanisms allow these networks to be rapidly redeployed in defense of host cytoplasm against microbial invaders. Both chemical and mechanical stimuli are recognized as danger signals to the plant, and these are perceived and transduced into cytoskeletal dynamics and architecture changes through a collection of well-recognized, previously characterized players. Recent advances in quantitative cell biology approaches, along with the powerful molecular genetics techniques associated with Arabidopsis, have uncovered two actin-binding proteins as key intermediaries in the immune response to phytopathogens and defense signaling. Certain bacterial phytopathogens have adapted to the cytoskeletal-based defense mechanism during the basal immune response and have evolved effector proteins that target actin filaments and microtubules to subvert transcriptional reprogramming, secretion of defense-related proteins, and cell wall–based defenses. In this review, we describe current knowledge about host cytoskeletal dynamics operating at the crossroads of the molecular and cellular arms race between microbes and plants.

Cyberloma acerinae. [Descriptions of Fungi and Bacteria].

2020 ◽  
Author(s):  
D. W. Minter
Keyword(s):  
Biological Control ◽  
Soviet Union ◽  
Former Soviet Union ◽  
Conservation Status ◽  
Control Programme ◽  
Novosibirsk Oblast ◽  
Invasive Fish ◽  
Checks And Balances ◽  
Host Cytoplasm ◽  
Host Nucleus

Abstract A description is provided for Cyberloma acerinae, which infects fish of the families Atherinidae, Gobiidae and Percidae in Europe; infections developing in the host cytoplasm (but not in nerve tissues), without diplokarya, and resulting in tumours (also known as 'xenomas') in which the host nucleus is centrally located. Some information on its dispersal and transmission, habitats and conservation status is given, along with details of its geographical distribution (Asia (Kazakhstan (Aktobe), Russia (Novosibirsk Oblast)) and Europe (Czech Republic, Finland, France, former Soviet Union, Ukraine)). No evaluation has been made of any possible positive economic impact of this species (e.g. as a source of useful products, as a provider of checks and balances within its ecosystem, etc.), although Kvach et al. (2014) observed that it parasitizes some invasive fish, and so may have potential as part of an integrated biological control programme.

Loma dimorpha. [Descriptions of Fungi and Bacteria].

2020 ◽  
Author(s):  
D. W. Minter
Keyword(s):  
Geographical Distribution ◽  
North Africa ◽  
Conservation Status ◽  
Host Cytoplasm ◽  
The Family ◽  
Host Nucleus

Abstract A description is provided for Loma dimorpha, which infects fish of the family Blenniidae and Gobiidae in seas off Europe and, possibly, north Africa; infections developing in the host cytoplasm (but not in nerve tissues), without diplokarya, and resulting in tumours (also known as 'xenomas') in which the host nucleus is centrally located. Some information on its dispersal and transmission, habitats and conservation status is given, along with details of its geographical distribution (Europe (France, Spain)).

scholarly journals Retroviral DNA Integration

1999 ◽  
Vol 63 (4) ◽  
pp. 836-843 ◽  
Author(s):  
Patrick Hindmarsh ◽  
Jonathan Leis
Keyword(s):  
Dna Sequences ◽  
Host Genome ◽  
Single Site ◽  
Enzyme Complex ◽  
Enzymatic Process ◽  
Long Terminal Repeats ◽  
Host Proteins ◽  
Viral Dna ◽  
Dna Integration ◽  
Terminal Repeats

SUMMARY DNA integration is a unique enzymatic process shared by all retroviruses and retrotransposons. During integration, double-stranded linear viral DNA is inserted into the host genome in a process catalyzed by the virus-encoded integrase (IN). The mechanism involves a series of nucleophillic attacks, the first of which removes the terminal 2 bases from the 3′ ends of the long terminal repeats and of the second which inserts the viral DNA into the host genome. IN specifically recognizes the DNA sequences at the termini of the viral DNA, juxtaposing both ends in an enzyme complex that inserts the viral DNA into a single site in a concerted manner. Small duplications of the host DNA, characteristic of the viral IN, are found at the sites of insertion. At least two host proteins, HMG-I(Y) and BAF, have been shown to increase the efficiency of the integration reaction.

scholarly journals Strain-Dependent Impact of G and SH Deletions Provide New Insights for Live-Attenuated HMPV Vaccine Development

Vaccines ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 164 ◽  
Author(s):  
Julia Dubois ◽  
Andrés Pizzorno ◽  
Marie-Hélène Cavanagh ◽  
Blandine Padey ◽  
Claire Nicolas de Lamballerie ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Specific Treatment ◽  
Respiratory Pathogen ◽  
Recombinant Viruses ◽  
Human Airway Epithelium ◽  
A Cell ◽  
Strain Dependent ◽  
Selection Of

Human metapneumovirus (HMPV) is a major pediatric respiratory pathogen with currently no specific treatment or licensed vaccine. Different strategies to prevent this infection have been evaluated, including live-attenuated vaccines (LAV) based on SH and/or G protein deletions. This approach showed promising outcomes but has not been evaluated further using different viral strains. In that regard, we previously showed that different HMPV strains harbor distinct in vitro fusogenic and in vivo pathogenic phenotypes, possibly influencing the selection of vaccine strains. In this study, we investigated the putative contribution of the low conserved SH or G accessory proteins in such strain-dependent phenotypes and generated recombinant wild type (WT) and SH- or G-deleted viruses derived from two different patient-derived HMPV strains, A1/C-85473 and B2/CAN98-75. The ΔSH and ΔG deletions led to different strain-specific phenotypes in both LLC-MK2 cell and reconstituted human airway epithelium models. More interestingly, the ΔG-85473 and especially ΔSH-C-85473 recombinant viruses conferred significant protection against HMPV challenge and induced immunogenicity against a heterologous strain. In conclusion, our results show that the viral genetic backbone should be considered in the design of live-attenuated HMPV vaccines, and that a SH-deleted virus based on the A1/C-85473 HMPV strain could be a promising LAV candidate as it is both attenuated and protective in mice while being efficiently produced in a cell-based system.

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