scholarly journals THE CYTONUCLEOPROTEINS OF AMEBAE

1963 ◽  
Vol 19 (3) ◽  
pp. 453-466 ◽  
Author(s):  
Thomas J. Byers ◽  
Dorothy B. Platt ◽  
Lester Goldstein
Keyword(s):  
Host Cell ◽  
Cell Nucleus ◽  
Amoeba Proteus ◽  
Host Cells ◽  
Binucleate Cell ◽  
Donor Nucleus ◽  
Random Manner ◽  
Host Cell Nucleus ◽  
Long Term Behavior

Autoradiographs of whole Amoeba proteus host cells fixed after the implantation of single nuclei from A. proteus donors labeled with any one of 8 different radioactive amino acids showed that the label had become highly concentrated in the host cell nucleus as well as in the donor nucleus and that the cytoplasmic activity was relatively low. When these amebae were sectioned, the radioactivity was found to be homogeneously distributed throughout the nuclei. The effect of unlabeled amino acid "chaser," the solubility of the labeled material, and the long-term behavior of the labeled material gave evidence that the radioactivity was in protein. At equilibrium, the host cell nucleus contained approximately 30 per cent of the radioactivity distributed between the two nuclei. This unequal nuclear distribution is attributed to the presence of two classes of nuclear proteins: a non-migratory one that does not leave the nucleus during interphase, and a migratory one, called cytonucleoprotein, that shuttles between nucleus and cytoplasm in a non-random manner. It is estimated that between 12 per cent and 44 per cent of the cytonucleoproteins are present in the cytoplasm of a binucleate cell at any one moment. Nuclei of Chaos chaos host cells also concentrated label acquired from implanted radioactive A. proteus nuclei.

scholarly journals An oomycete effector protein induces shade avoidance in Arabidopsis and attenuates salicylate signaling by binding to host proteins of the RADICAL-INDUCED CELL DEATH1 family

2017 ◽  
Author(s):  
Lennart Wirthmueller ◽  
Shuta Asai ◽  
Ghanasyam Rallapalli ◽  
Jan Sklenar ◽  
Georgina Fabro ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Host Cell ◽  
Cell Nucleus ◽  
Induced Defense ◽  
Marker Gene ◽  
Effector Proteins ◽  
Host Cells ◽  
Shade Avoidance ◽  
Triple Mutant ◽  
Host Cell Nucleus

AbstractThe oomycete pathogen Hyaloperonospora arabidopsidis (Hpa) causes downy mildew disease on Arabidopsis. During infection, Hpa like other biotrophic pathogens, suppresses activation of plant innate immunity by translocating effector proteins into host cells. Some of these effectors localize to the host cell nucleus where they may manipulate transcriptional reprogramming of plant defense genes. Here we report that the nuclear-localized Hpa effector HaRxL106, when expressed in Arabidopsis, induces shade avoidance and attenuates the transcriptional response to the defense signaling molecule salicylic acid. HaRxL106 interacts with RADICAL-INDUCED CELL DEATH1 (RCD1) and loss of RCD1 function renders Arabidopsis resilient against HaRxL106-mediated suppression of immunity. To further characterize the molecular functions of RCD1 we solved a crystal structure of RCD1’s Poly-(ADP-ribose)-Polymerase (PARP) domain and, based on non-conservation of amino acids constituting the active site of canonical PARPs, conclude that RCD1 has no PARP activity. We report that RCD1-type proteins are phosphorylated and identified histone-modifying Mut9-like kinases (MLKs) as RCD1-interacting proteins. A mlk1,3,4 triple mutant exhibits stronger SA-induced defense marker gene expression compared to wild-type plants. Our data suggest that HaRxL106 suppresses Arabidopsis innate immunity by manipulating the function(s) of RCD1 in the host cell nucleus and point towards a role of RCD1 as a transcriptional co-regulator that integrates signals from light and pathogen sensors.

scholarly journals Rapid evolution of decreased host susceptibility drives a stable relationship between ultrasmall parasite TM7x and its bacterial host

2018 ◽  
Vol 115 (48) ◽  
pp. 12277-12282 ◽  
Author(s):  
Batbileg Bor ◽  
Jeffrey S. McLean ◽  
Kevin R. Foster ◽  
Lujia Cen ◽  
Thao T. To ◽  
...  
Keyword(s):  
Host Cell ◽  
Rapid Evolution ◽  
Host Population ◽  
Host Cells ◽  
Host Susceptibility ◽  
Bacterial Host ◽  
Narrow Host Range ◽  
Stable Relationship ◽  
Candidate Phyla Radiation

Around one-quarter of bacterial diversity comprises a single radiation with reduced genomes, known collectively as the Candidate Phyla Radiation. Recently, we coisolated TM7x, an ultrasmall strain of the Candidate Phyla Radiation phylum Saccharibacteria, with its bacterial host Actinomyces odontolyticus strain XH001 from human oral cavity and stably maintained as a coculture. Our current work demonstrates that within the coculture, TM7x cells establish a long-term parasitic association with host cells by infecting only a subset of the population, which stay viable yet exhibit severely inhibited cell division. In contrast, exposure of a naïve A. odontolyticus isolate, XH001n, to TM7x cells leads to high numbers of TM7x cells binding to each host cell, massive host cell death, and a host population crash. However, further passaging reveals that XH001n becomes less susceptible to TM7x over time and enters a long-term stable relationship similar to that of XH001. We show that this reduced susceptibility is driven by rapid host evolution that, in contrast to many forms of phage resistance, offers only partial protection. The result is a stalemate where infected hosts cannot shed their parasites; nevertheless, parasite load is sufficiently low that the host population persists. Finally, we show that TM7x can infect and form stable long-term relationships with other species in a single clade of Actinomyces, displaying a narrow host range. This system serves as a model to understand how parasitic bacteria with reduced genomes such as those of the Candidate Phyla Radiation have persisted with their hosts and ultimately expanded in their diversity.

scholarly journals The dps Gene of Symbiotic “Candidatus Legionella jeonii” in Amoeba proteus Responds to Hydrogen Peroxide and Phagocytosis

2006 ◽  
Vol 188 (21) ◽  
pp. 7572-7580 ◽  
Author(s):  
Miey Park ◽  
Seong Tae Yun ◽  
Sue-Yun Hwang ◽  
Choong-Ill Chun ◽  
Tae In Ahn
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Host Cell ◽  
Genomic Library ◽  
Amoeba Proteus ◽  
Host Cells ◽  
Intracellular Pathogens ◽  
Protective Mechanisms ◽  
Dps Protein ◽  
Cloned Gene

ABSTRACT To survive in host cells, intracellular pathogens or symbiotic bacteria require protective mechanisms to overcome the oxidative stress generated by phagocytic activities of the host. By genomic library tagging, we cloned a dps (stands for DNA-binding protein from starved cells) gene of the symbiotic “Candidatus Legionella jeonii” organism (called the X bacterium) (dps X) that grows in Amoeba proteus. The gene encodes a 17-kDa protein (pI 5.19) with 91% homology to Dps and DNA-binding ferritin-like proteins of other organisms. The cloned gene complemented the dps mutant of Escherichia coli and conferred resistance to hydrogen peroxide. DpsX proteins purified from E. coli transformed with the dps X gene were in oligomeric form, formed a complex with pBlueskript SKII DNA, and protected the DNA from DNase I digestion and H2O2-mediated damage. The expression of the dps X gene in “Candidatus Legionella jeonii” was enhanced when the host amoeba was treated with 2 mM H2O2 and by phagocytic activities of the host cell. These results suggested that the Dps protein has a function protective of the bacterial DNA and that its gene expression responds to oxidative stress generated by phagocytic activities of the host cell. With regard to the fact that invasion of Legionella sp. into respiratory phagocytic cells causes pneumonia in mammals, further characterization of dps X expression in the Legionella sp. that multiplies in a protozoan host in the natural environment may provide valuable information toward understanding the protective mechanisms of intracellular pathogens.

Lysis of bacterioids in the vicinity of the host cell nucleus in an ineffective (fix-) root nodule of soybean (Glycine max)

Planta ◽  
1984 ◽  
Vol 162 (1) ◽  
pp. 8-16 ◽  
Author(s):  
Dietrich Werner ◽  
Erhard M�rschel ◽  
Renate Kort ◽  
Robert B. Mellor ◽  
Stephan Bassarab
Keyword(s):  
Glycine Max ◽  
Host Cell ◽  
Cell Nucleus ◽  
Root Nodule ◽  
Host Cell Nucleus

scholarly journals The journey of herpesvirus capsids and genomes to the host cell nucleus

2021 ◽  
Vol 50 ◽  
pp. 147-158
Author(s):  
Katinka Döhner ◽  
Angela Cornelius ◽  
Manutea Christophe Serrero ◽  
Beate Sodeik
Keyword(s):  
Host Cell ◽  
Cell Nucleus ◽  
Host Cell Nucleus

ARE LEUCOCYTOZOON SAKHAROFFI SAMBON AND LEUCOCYTOZOON BERESTNEFFI SAMBON SYNONYMOUS?

1950 ◽  
Vol 28d (1) ◽  
pp. 1-4 ◽  
Author(s):  
A. Murray Fallis
Keyword(s):  
Host Cell ◽  
Cell Nucleus ◽  
Infected Cells ◽  
Host Cell Nucleus

The size of the gametocytes of a leucocytozoon in young crows shows a wide variation in birds obtained in different localities. The host cell nucleus of infected cells may be pushed to one side, almost surround the parasite, or be intermediate between these extremes. Previous descriptions, given by various authors, of Leucocytozoon sakharoffi and L. berestneffi show similar differences in these characters. L. berestneffi is considered therefore to be a synonym of L. sakharoffi.

scholarly journals Host Cell Subversion by Toxoplasma GRA16, an Exported Dense Granule Protein that Targets the Host Cell Nucleus and Alters Gene Expression

2013 ◽  
Vol 13 (4) ◽  
pp. 489-500 ◽  
Author(s):  
Alexandre Bougdour ◽  
Eric Durandau ◽  
Marie-Pierre Brenier-Pinchart ◽  
Philippe Ortet ◽  
Mohamed Barakat ◽  
...  
Keyword(s):  
Gene Expression ◽  
Host Cell ◽  
Cell Nucleus ◽  
Dense Granule ◽  
Granule Protein ◽  
Host Cell Nucleus
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