scholarly journals NH2-terminal acetylation of Dictyostelium discoideum actin in a cell-free protein-synthesizing system.

1981 ◽  
Vol 256 (15) ◽  
pp. 8149-8155 ◽  
Author(s):  
P. Rubenstein ◽  
P. Smith ◽  
J. Deuchler ◽  
K. Redman
Keyword(s):  
Dictyostelium Discoideum ◽  
Free Protein ◽  
A Cell

scholarly journals Mapping of a cell-binding domain in the cell adhesion molecule gp80 of Dictyostelium discoideum.

1988 ◽  
Vol 107 (5) ◽  
pp. 1835-1843 ◽  
Author(s):  
R K Kamboj ◽  
L M Wong ◽  
T Y Lam ◽  
C H Siu
Keyword(s):  
Cell Adhesion ◽  
Dictyostelium Discoideum ◽  
Fusion Proteins ◽  
Binding Activity ◽  
Binding Domain ◽  
Globular Domain ◽  
Cell Binding ◽  
Homophilic Interaction ◽  
A Cell ◽  
Cell Binding Domain

At the aggregation stage of Dictyostelium discoideum development, a cell surface glycoprotein of Mr 80,000 (gp80) has been found to mediate the EDTA-resistant type of cell-cell adhesion via homophilic interaction (Siu, C.-H., A. Cho, and A. H. C. Choi. 1987. J. Cell Biol. 105:2523-2533). To investigate the structure-function relationships of gp80, we have isolated full length cDNA clones for gp80 and determined the DNA sequence. The deduced structure of gp80 showed three major domains. An amino-terminal globular domain composed of the bulk of the protein is supported by a short stalk region, which is followed by a membrane anchor at the carboxy terminus. Structural analysis suggested that the cell-binding domain of gp80 resides within the globular domain near the amino terminus. To investigate the relationship of the cell-binding activity to this region of the polypeptide, three protein A/gp80 (PA80) gene fusions were constructed using the expression vector pRIT2T. These PA80 fusion proteins were assayed for their ability to bind to aggregation stage cells. Binding of 125I-labeled fusion proteins PA80I (containing the Val123 to Ile514 fragment of gp80) and PA80II (Val123 to Ala258) was dosage dependent and could be inhibited by precoating cells with the cell cohesion-blocking mAb 80L5C4. On the other hand, there was no appreciable binding of PA80III (Ile174 to Ile514) to cells. Reassociation of cells was significantly inhibited in the presence of PA80I or PA80II. In addition, 125I-labeled PA80II exhibited homophilic interaction with immobilized PA80I, PA80II, or gp80. The results of these studies lead to the mapping of a cell-binding domain in the region between Val123 and Leu173 of gp80 and provide direct evidence that the cell-binding activity of gp80 resides in the protein moiety.

scholarly journals Hypoxia triggers collective aerotactic migration in Dictyostelium discoideum

2020 ◽  
Author(s):  
O. Cochet-Escartin ◽  
M. Demircigil ◽  
S. Hirose ◽  
B. Allais ◽  
P. Gonzalo ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Communication ◽  
Quantitative Agreement ◽  
Cellular Potts Model ◽  
Detection Mechanism ◽  
Cell Behaviors ◽  
Dense Ring ◽  
Efficient Detection ◽  
Technological Developments ◽  
A Cell

AbstractIt is well known that eukaryotic cells can sense oxygen (O2) and adapt their metabolism accordingly. It is less known that they can also move towards regions of higher oxygen level (aerotaxis). Using a self-generated hypoxic assay, we show that the social amoeba Dictyostelium discoideum displays a spectacular aerotactic behavior. When a cell colony is covered by a coverglass, cells quickly consume the available O2 and the ones close to the periphery move directionally outward forming a dense ring keeping a constant speed and density. To confirm that O2 is the main molecular player in this seemingly collective process, we combined two technological developments, porphyrin based O2 sensing films and microfluidic O2 gradient generators. We showed that Dictyostelium cells exhibit aerotactic and aerokinetic (increased speed at low O2) response in an extremely low range of O2 concentration (0-1.5%) indicative of a very efficient detection mechanism. The various cell behaviors under self-generated or imposed O2 gradients were modeled with a very satisfactory quantitative agreement using an in silico cellular Potts model built on experimental observations. This computational model was complemented with a parsimonious ‘Go or Grow’ partial differential equation (PDE) model. In both models, we found that the collective migration of a dense ring can be explained by the interplay between cell division and the modulation of aerotaxis, without the need for cell-cell communication.

γ-Bestrahlte Ribosomen von Micrococcus radiodurans in einem System der zellfreien Proteinsynthese / γ-Irradiated Ribosomes from Micrococcus radiodurans in a Cell-Free Protein Synthesizing System

1979 ◽  
Vol 34 (7-8) ◽  
pp. 565-569 ◽  
Author(s):  
Roland Süssmuth ◽  
Annette Widmann
Keyword(s):  
Magnesium Content ◽  
Radiation Sensitivity ◽  
Γ Irradiation ◽  
Free Protein ◽  
E Coli ◽  
Directed Synthesis ◽  
A Cell

Abstract γ-irradiation inactivation of isolated ribosomes of Micrococcus radiodurans was studied by ex amining poly U directed synthesis of polyphenylalanine. Ribosomes of M . radiodurans did not show significant y-radiation sensitivity up to a dose of approx. 11.6k Gy. Cells of M . radiodurans take up more magnesium than E. coli cells unter the same conditions. The magnesium content of ribosomes of M . radiodurans was 18% higher than that of E. coli ribosomes. A possible relation between Mg2+-content and γ-resistance is discussed.

scholarly journals Targeted disruption of genes for gp138, a cell-fusion-related protein in Dictyostelium discoideum, revealed the existence of a third gene

1996 ◽  
Vol 38 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Mikihiko Higa ◽  
Kazuhiro Aiba ◽  
Hui Fang ◽  
Yoshimasa Tanaka ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Fusion ◽  
Related Protein ◽  
Targeted Disruption ◽  
A Cell

scholarly journals Excitation, adaption, and deadaptation of the cAMP-mediated cGMP Response in dictyostelium discoideum

1983 ◽  
Vol 96 (2) ◽  
pp. 347-353 ◽  
Author(s):  
PJM Van Haaster ◽  
PR Van Der Heijden
Keyword(s):  
Cell Suspension ◽  
Dictyostelium Discoideum ◽  
Half Life ◽  
Cell Aggregation ◽  
First Order ◽  
Intracellular Cgmp ◽  
First Order Kinetics ◽  
A Cell ◽  
Stimulation Period ◽  
Extracellular Camp

Extracellular cAMP induces chemotaxis and cell aggregation in dictyostelium discoideum cells. cAMP added to a cell suspension is rapidly hydrolyzed (half-life of 10 s) and induces a rapid increase of intracellular cGMP levels, which reach a peak at 10 s and recover prestimulated levels at about 30 s. This recovery is not due to removal of the stimulus because the nonhydrolyzable analogue adenosine 3',5'-monophosphorothioate-Sp- stereoisomer (cAMPS) induced a comparable cGMP response, which peaked at 10 s, even at subsaturating cAMPS concentrations. When cells were stimulated twice with the same cAMP concentration at a 30-s interval, only the first stimulus produced a cGMP response. Cells did respond to the second stimulus when the concentration of the second stimulus was higher than that of the first stimulus. By increasing the interval between two identical stimuli, the response to the second stimulus gradually increased. Recovery from the first stimulus showed first-order kinetics with a half-life of 1-2 min. The stimulation period was shortened by adding phosphodieterase to the cell suspension. The cGMP response was unaltered if the half-life of cAMP was reduced to 2 S. The peak of the transient cGMP accumulation still appeared at 10 s even when the half- life of cAMP was 0.4 s; however, the height of the cGMP peak was reduced. The cGMP response at 10 s after stimulation was diminished by 50 percent when the half-life of 10(-7) M cAMP was 0.5 s or when the half-life of 10(-8) M cAMP was 3.0 s. These results show that the cAMP signal is transduced to two opposing processes: excitation and adaptation. Within 10 s after addition of cAMP to a cell suspension the level of adaptation reaches the level of excitation, which causes the extinction of the transduction of the signal. Deadaptation starts as soon as the signal is removed, and it has first-order kinetics with a half-life of 1-2 min.

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