Proteinases of Leishmania mexicana and other flagellate protozoa

Parasitology ◽  
1982 ◽  
Vol 84 (1) ◽  
pp. 149-155 ◽  
Author(s):  
G. H. Coombs
Keyword(s):  
Primary Factor ◽  
Proteinase Activity ◽  
Cysteine Proteinases ◽  
Human Pathogen ◽  
Leishmania Mexicana ◽  
Amastigote Form ◽  
Promastigote Form ◽  
Survival And Growth ◽  
Very High

SUMMARYThe amastigote form of the human pathogen Leishmania mexicana contains high proteinase activity, some 20 times greater than that in the promastigote form and macrophages and appreciably higher than the activity in other flagellate protozoa. The main amastigote enzymes are soluble, whereas those of the promastigote are particulate, and have inhibitor sensitivities characteristic of cysteine proteinases. The very high soluble proteinase activity of L. mexicana amastigotes may be a primary factor in the survival and growth of this mammalian stage in its potentially degradative intracellular habitat.

Intracellular interactions of Leishmania mexicana with a cell line from Toxorhynchites amboinensis (77M-248) larvae

1994 ◽  
Vol 52 ◽  
pp. 268-269
Author(s):  
Carlos Argüello
Keyword(s):  
Cell Line ◽  
Membrane Receptors ◽  
Specific Cell ◽  
Leishmania Mexicana ◽  
Amastigote Form ◽  
Different Temperatures ◽  
Two Distinct Temperatures ◽  
A Cell ◽  
Promastigote Form

Leishmania is an intracellular parasite that lives in phagocytic vacuoles of macrophages . The promastigote form of the parasite is flagellated and interacts with macrophages through specific cell membrane receptors . Once inside phagocytic vacuoles, the parasite differentiates into the amastigote form which is small and aflagellated. Part of the life cycle of the parasite occurs in the lumen of the digestive tract of an insect, with a body temperature of 25-27 °C that promotes the preferential differentiation of the promastigote form. A cell line ( TRA-248 ) isolated from Toxorhynchites amboinensis has been adapted to grow at two different temperatures 24° and 34°C, and used in the study of dengue virus. This quality of TRA-248 cells is of relevance since they permit to analyze the behavior of leishmania in an insect cell at two distinct temperatures. In this study, TRA- 248 cells and promastigotes interacted in culture at 24° and 34°C, for 12, 24 and 48 hrs and determine if the parasites are phagocyted and able to differentiate into the amastigote form. Also, the activity of acid phosphatase was compared between TRA-248 cells and macrophages.

Distribution of parasite cysteine proteinases in lesions of mice infected with Leishmania mexicana amastigotes

1994 ◽  
Vol 67 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Thomas Ilg ◽  
Manuela Fuchs ◽  
Volker Gnau ◽  
Markus Wolfram ◽  
Dorothee Harbecke ◽  
...  
Keyword(s):  
Cysteine Proteinases ◽  
Leishmania Mexicana

scholarly journals Suicidal Leishmania

Pathogens ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 79 ◽  
Author(s):  
Lucie Podešvová ◽  
Tereza Leštinová ◽  
Eva Horáková ◽  
Julius Lukeš ◽  
Petr Volf ◽  
...  
Keyword(s):  
Cell Death ◽  
Phospholipase A2 ◽  
Cutaneous Leishmaniasis ◽  
Human Pathogen ◽  
Leishmania Mexicana ◽  
Macrophage Infection ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Tropical Infections

Leishmania are obligate intracellular parasites known to have developed successful ways of efficient immunity evasion. Because of this, leishmaniasis, a disease caused by these flagellated protists, is ranked as one of the most serious tropical infections worldwide. Neither prophylactic medication, nor vaccination has been developed thus far, even though the infection has usually led to strong and long-lasting immunity. In this paper, we describe a “suicidal” system established in Leishmania mexicana, a human pathogen causing cutaneous leishmaniasis. This system is based on the expression and (de)stabilization of a basic phospholipase A2 toxin from the Bothrops pauloensis snake venom, which leads to the inducible cell death of the parasites in vitro. Furthermore, the suicidal strain was highly attenuated during macrophage infection, regardless of the toxin stabilization. Such a deliberately weakened parasite could be used to vaccinate the host, as its viability is regulated by the toxin stabilization, causing a profoundly reduced pathogenesis.

scholarly journals Activation of oxidized cysteine proteinases by thioredoxin-mediated reduction in vitro

1993 ◽  
Vol 291 (2) ◽  
pp. 345-347 ◽  
Author(s):  
A G Stephen ◽  
R Powls ◽  
R J Beynon
Keyword(s):  
Thioredoxin Reductase ◽  
Proteinase Activity ◽  
Cysteine Proteinases ◽  
Thioredoxin System ◽  
Mediated Reduction ◽  
Oxidative Attack

Activity of the cysteine adducts of the cysteine proteinases papain and thaumatopain can be recovered by treatment with thioredoxin, thioredoxin reductase and NADPH. Recovery of proteinase activity did not occur if any of the components of the thioredoxin system were omitted, or if thioredoxin or thioredoxin reductase were heat-inactivated. Such an enzyme-mediated process may be of significance in the recovery of cysteine proteinases inactivated by oxidative attack.

Effect of Overhead Spray and Brush Roller Treatment on the Survival of Pectobacterium and Salmonella on Tomato Surfaces

2015 ◽  
Vol 78 (1) ◽  
pp. 51-56 ◽  
Author(s):  
ALINA N. BALAGUERO ◽  
ASWATHY SREEDHARAN ◽  
KEITH R. SCHNEIDER
Keyword(s):  
Relative Humidity ◽  
Plant Pathogen ◽  
Tomato Fruit ◽  
Soft Rot ◽  
Human Pathogen ◽  
Physical Damage ◽  
Tomato Quality ◽  
Negative Effect ◽  
Survival And Growth ◽  
Salmonella Survival

Overhead spray and brush roller (OSBR) treatment has been shown to remove significantly more Salmonella from tomato surfaces than flume treatment. However, OSBR is not widely used in tomato packing facilities compared with other commodities, and little is known about whether brushing causes microabrasions or other physical damage. Bacteria such as Pectobacterium, a soft rot–producing plant pathogen, and Salmonella, a human pathogen, show increased survival and growth on damaged tomato surfaces. This study evaluated whether OSBR treatment had a negative effect on the safety and/or marketability of tomatoes by examining its effect on Pectobacterium and Salmonella survival. Pectobacterium survival was evaluated on inoculated tomatoes that were OSBR treated with water or sanitizer (100 ppm of NaOCl, 5 ppm of ClO2, or 80 ppm of peracetic acid). A 15-s OSBR treatment using water or sanitizer achieved a 3-log CFU/ml reduction in Pectobacterium levels. Survival of Pectobacterium and Salmonella on OSBR-treated, untreated, and puncture-wounded tomatoes stored at 25°C and 75 to 85% relative humidity for 7 days was also assessed. Both Pectobacterium and Salmonella populations declined rapidly on OSBR-treated and untreated tomatoes, indicating that brushing does not damage tomato fruit to the extent of promoting better pathogen survival. In contrast, the survival of both organisms was significantly (P ≤ 0.05) higher on artificially wounded fruit. These results indicate that OSBR treatment does not increase the survival and growth of Pectobacterium or Salmonella on tomato surfaces and that it is effective in reducing Pectobacterium levels on the surface of inoculated tomatoes. These results suggest that, if used properly, an OSBR system in packinghouses is effective in removing surface contamination and does not affect tomato quality or safety.

scholarly journals Effect of Browsing, Seedbed, and Competition on the Development of Yellow Birch Seedlings in High-Graded Stands

2009 ◽  
Vol 26 (3) ◽  
pp. 99-105 ◽  
Author(s):  
Jean-Gabriel Elie ◽  
Jean-Claude Ruel ◽  
Jean-Martin Lussier
Keyword(s):  
Major Effect ◽  
Growth Potential ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Growth And Survival ◽  
Early Seedling ◽  
Survival And Growth ◽  
Further Development ◽  
Very High ◽  
Mixedwood Stands

Abstract Many hardwood or mixedwood stands of northeastern North America have been high graded in the past and need restoration treatments to bring them back to an acceptable level of production. Even when early seedling establishment can be secured, further development may be compromised bymany factors. This study looks at the effect of seedbed, browsing, and competition on the growth and survival of yellow birch (Betula alleghaniensis Britt.) seedlings that became established after a brushing and scarification treatment applied in high-graded mixedwood stands of Quebec,Canada. The seedbed types studied include 1-m-wide scarified patches, 2-m-wide scarified patches, and mounds. Browsing impact was assessed by placing fences around half of the plots. Half of the plots were released from competing vegetation. Browsing by hare (Lepus americanus) was seenas a major factor controlling seedling development between 3 and 6 years after scarification. It reduced both survival and growth and obscured the effect of other factors. In the absence of browsing, competition had a major effect on mounds but not on scarified patches. Mounds were found tohave the best growth potential when competition and browsing were controlled. The scarified patches had the best growth when competition and browsing were allowed. Even though mortality was somewhat higher on scarified patches, initial densities were very high and still provide more seedlingsthan required.

scholarly journals Structural analysis of the OC43 coronavirus 2′-O-RNA methyltransferase

2021 ◽  
Author(s):  
Pavel Dostalik ◽  
Petra Krafcikova ◽  
Jan Silhan ◽  
Evzen Boura
Keyword(s):  
Structural Analysis ◽  
Rna Stability ◽  
Binding Pocket ◽  
Human Pathogen ◽  
C Terminus ◽  
N Terminus ◽  
High Conservation ◽  
The Common ◽  
Human Coronaviruses ◽  
Very High

The OC43 coronavirus is a human pathogen that usually causes only the common cold. One of its key enzymes, similar to other coronaviruses, is the 2′-O-RNA methyltransferase (MTase) that is essential for viral RNA stability and expression. Here, we report the crystal structure of the 2′-O-RNA MTase in a complex with the pan-methyltransferase inhibitor sinefungin solved at 2.2 Å resolution. The structure revealed an overall fold consistent with the fold observed in other coronaviral MTases. The major differences are in the conformation of the C-terminus of the nsp16 subunit and an additional helix in the N-terminus of the nsp10 subunits. The structural analysis also revealed very high conservation of the SAM binding pocket suggesting that the SAM pocket is a suitable spot for the design of antivirals effective against all human coronaviruses.

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