scholarly journals Protein Serine/Threonine Phosphatase Type 2C of Leishmania mexicana

2021 ◽  
Vol 11 ◽  
Author(s):  
Alma Reyna Escalona-Montaño ◽  
Mariana Zuñiga-Fabián ◽  
Nallely Cabrera ◽  
Ricardo Mondragón-Flores ◽  
Jenny Nancy Gómez-Sandoval ◽  
...  
Keyword(s):  
Tyrosine Phosphatase ◽  
Specific Inhibitor ◽  
Protozoan Parasite ◽  
Structural Diversity ◽  
Flagellar Pocket ◽  
Leishmania Mexicana ◽  
Phosphatase Inhibitors ◽  
Cell Functions ◽  
Transmission Electron ◽  
The Family

Protein phosphorylation and dephosphorylation are increasingly recognized as important processes for regulating multiple physiological mechanisms. Phosphorylation is carried out by protein kinases and dephosphorylation by protein phosphatases. Phosphoprotein phosphatases (PPPs), one of three families of protein serine/threonine phosphatases, have great structural diversity and are involved in regulating many cell functions. PP2C, a type of PPP, is found in Leishmania, a dimorphic protozoan parasite and the causal agent of leishmaniasis. The aim of this study was to clone, purify, biochemically characterize and quantify the expression of PP2C in Leishmania mexicana (LmxPP2C). Recombinant LmxPP2C dephosphorylated a specific threonine (with optimal activity at pH 8) in the presence of the manganese divalent cation (Mn+2). LmxPP2C activity was inhibited by sanguinarine (a specific inhibitor) but was unaffected by protein tyrosine phosphatase inhibitors. Western blot analysis indicated that anti-LmxPP2C antibodies recognized a molecule of 45.2 kDa. Transmission electron microscopy with immunodetection localized LmxPP2C in the flagellar pocket and flagellum of promastigotes but showed poor staining in amastigotes. Interestingly, LmxPP2C belongs to the ortholog group OG6_142542, which contains only protozoa of the family Trypanosomatidae. This suggests a specific function of the enzyme in the flagellar pocket of these microorganisms.

Processing and trafficking of cysteine proteases in Leishmania mexicana

2000 ◽  
Vol 113 (22) ◽  
pp. 4035-4041 ◽  
Author(s):  
D.R. Brooks ◽  
L. Tetley ◽  
G.H. Coombs ◽  
J.C. Mottram
Keyword(s):  
Cysteine Protease ◽  
Mammalian Cells ◽  
Protozoan Parasite ◽  
Cysteine Proteases ◽  
Glycosylation Site ◽  
Site Directed Mutagenesis ◽  
Flagellar Pocket ◽  
Leishmania Mexicana

Removal of the pro-domain of a cysteine protease is essential for activation of the enzyme. We have engineered a cysteine protease (CPB2.8) of the protozoan parasite Leishmania mexicana by site-directed mutagenesis to remove the active site cysteine (to produce CPB(C25G)). When CPB(C25G) was expressed in a L. mexicana mutant lacking all CPB genes, the inactive pro-enzyme was processed to the mature protein and trafficked to the lysosome. These results show that auto-activation is not required for correct processing of CPB in vivo. When CPB(C25G) was expressed in a L. mexicana mutant lacking both CPA and CPB genes, the majority of the pro-enzyme remained unprocessed and accumulated in the flagellar pocket. These data reveal that CPA can directly or indirectly process CPB(C25G) and suggest that cysteine proteases are targeted to lysosomes via the flagellar pocket. Moreover, they show that another protease can process CPB in the absence of either CPA or CPB, albeit less efficiently. Abolition of the glycosylation site in the mature domain of CPB did not affect enzyme processing, targeting or in vitro activity towards gelatin. This indicates that glycosylation is not required for trafficking. Together these findings provide evidence that the major route of trafficking of Leishmania cysteine proteases to lysosomes is via the flagellar pocket and therefore differs significantly from cysteine protease trafficking in mammalian cells.

scholarly journals Characterization of polymer release from the flagellar pocket of Leishmania mexicana promastigotes.

1994 ◽  
Vol 125 (2) ◽  
pp. 321-331 ◽  
Author(s):  
Y D Stierhof ◽  
T Ilg ◽  
D G Russell ◽  
H Hohenberg ◽  
P Overath
Keyword(s):  
Culture Medium ◽  
Protozoan Parasite ◽  
Flagellar Pocket ◽  
Leishmania Mexicana ◽  
Electron Microscopic ◽  
Fibrous Network ◽  
Intracellular Compartments ◽  
Polymeric Structures ◽  
Microscopic Techniques

Trypanosomatids contain a unique compartment, the flagellar pocket, formed by an invagination of the plasma membrane at the base of the flagellum, which is considered to be the sole cellular site for endocytosis and exocytosis of macromolecules. The culture supernatant of Leishmania mexicana promastigotes, the insect stage of this protozoan parasite, contains two types of polymers: a filamentous acid phosphatase (sAP) composed of a 100-kD phosphoglycoprotein with non-covalently associated proteo high molecular weight phosphoglycan (proteo-HMWPG) and fibrous material termed network consisting of complex phosphoglycans. Secretion of both polymers is investigated using mAbs and a combination of light and electron microscopic techniques. Long filaments of sAP are detectable in the lumen of the flagellar pocket. Both sAP filaments and network material emerge from the ostium of the flagellar pocket. While sAP filaments detach from the cells, the fibrous network frequently remains associated with the anterior end of the parasites and can be found in the center of cell aggregates. The related species L. major forms similar networks. Since polymeric structures cannot be detected in intracellular compartments, it is proposed that monomeric or, possibly, oligomeric subunits synthesized in the cells are secreted into the flagellar pocket. Polymer formation from subunits is suggested to occur in the lumen of the pocket before release into the culture medium or, naturally, into the gut of infected sandflies.

Design and Biological Evaluation of Novel Imidazolyl Flavonoids as Potent and Selective Protein Tyrosine Phosphatase Inhibitors

2020 ◽  
Vol 16 (4) ◽  
pp. 563-574 ◽  
Author(s):  
Rong Y. Han ◽  
Yu Ge ◽  
Ling Zhang ◽  
Qing M. Wang
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Structural Features ◽  
Biological Evaluation ◽  
Cell Protein ◽  
Phosphatase Inhibitors ◽  
Protein Tyrosine ◽  
Therapeutic Development ◽  
Chemical Studies

Background: Protein tyrosine phosphatases 1B are considered to be a desirable validated target for therapeutic development of type II diabetes and obesity. Methods: A new series of imidazolyl flavonoids as potential protein tyrosine phosphatase inhibitors were synthesized and evaluated. Results: Bioactive results indicated that some synthesized compounds exhibited potent protein phosphatase 1B (PTP1B) inhibitory activities at the micromolar range. Especially, compound 8b showed the best inhibitory activity (IC50=1.0 µM) with 15-fold selectivity for PTP1B over the closely related T-cell protein tyrosine phosphatase (TCPTP). Cell viability assays indicated that 8b is cell permeable with lower cytotoxicity. Molecular modeling and dynamics studies revealed the reason for selectivity of PTP1B over TCPTP. Quantum chemical studies were carried out on these compounds to understand the structural features essential for activity. Conclusion: Compound 8b should be a potential selective PTP1B inhibitor.

scholarly journals Resolving few-layer antimonene/graphene heterostructures

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Tushar Gupta ◽  
Kenan Elibol ◽  
Stefan Hummel ◽  
Michael Stöger-Pollach ◽  
Clemens Mangler ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Structural Diversity ◽  
Growth Behavior ◽  
Oxide Formation ◽  
Rich Phase ◽  
One Dimensional ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Substrate Properties ◽  
The Rich

AbstractTwo-dimensional (2D) antimony (Sb, “antimonene”) is of interest in electronics and batteries. Sb however exhibits a large allotropic structural diversity, which is also influenced by its support. Thus, Sb heterostructure formation is key in 2D Sb integration. Particularly, 2D Sb/graphene interfaces are important. We thus study here few-layered 2D Sb/graphene heterostructures with atomic resolution (scanning) transmission electron microscopy. We find two Sb morphologies to coexist: first, a 2D morphology of layered β-Sb with β-Sb(001)||graphene(001) texture. Second, one-dimensional Sb nanowires which can be matched to β-Sb[2-21]⊥graphene(001) and are closely related to cubic Sb(001)||graphene(001). Importantly, both Sb morphologies show rotational van-der-Waals epitaxy with graphene. Both are resilient against oxidation, although superficial Sb-oxide formation merits consideration, including epitaxial Sb2O3(111)/β-Sb(001) heterostructures. Exact Sb growth behavior depends on processing and substrate properties including, notably, the support underneath the graphene. Our work elucidates the rich phase and epitaxy landscape in 2D Sb and 2D Sb/graphene heterostructures.

scholarly journals Antitrypanosomal and Antileishmanial Activity of Chalcones and Flavanones from Polygonum salicifolium

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 175
Author(s):  
Ahmed M. Zheoat ◽  
Samya Alenezi ◽  
Ehab Kotb Elmahallawy ◽  
Marzuq A. Ungogo ◽  
Ali H. Alghamdi ◽  
...  
Keyword(s):  
Human Cell Line ◽  
Antileishmanial Activity ◽  
Cross Resistance ◽  
Future Research ◽  
Parasitic Diseases ◽  
Leishmania Mexicana ◽  
First Line ◽  
Trypanosoma Brucei Brucei ◽  
The Family

Trypanosomiasis and leishmaniasis are a group of neglected parasitic diseases caused by several species of parasites belonging to the family Trypansomatida. The present study investigated the antitrypanosomal and antileishmanial activity of chalcones and flavanones from Polygonum salicifolium, which grows in the wetlands of Iraq. The phytochemical evaluation of the plant yielded two chalcones, 2′,4′-dimethoxy-6′-hydroxychalcone and 2′,5′-dimethoxy-4′,6′-dihydroxychalcone, and two flavanones, 5,7-dimethoxyflavanone and 5,8-dimethoxy-7-hydroxyflavanone. The chalcones showed a good antitrypanosomal and antileishmanial activity while the flavanones were inactive. The EC50 values for 2′,4′-dimethoxy-6′-hydroxychalcone against Trypanosoma brucei brucei (0.5 μg/mL), T. congolense (2.5 μg/mL), and Leishmania mexicana (5.2 μg/mL) indicated it was the most active of the compounds. None of the compounds displayed any toxicity against a human cell line, even at 100 µg/mL, or cross-resistance with first line clinical trypanocides, such as diamidines and melaminophenyl arsenicals. Taken together, our study provides significant data in relation to the activity of chalcones and flavanones from P. salicifolium against both parasites in vitro. Further future research is suggested in order to investigate the mode of action of the extracted chalcones against the parasites.

Structure-Based Design and Discovery of Protein Tyrosine Phosphatase Inhibitors Incorporating Novel Isothiazolidinone Heterocyclic Phosphotyrosine Mimetics

2005 ◽  
Vol 48 (21) ◽  
pp. 6544-6548 ◽  
Author(s):  
Andrew P. Combs ◽  
Eddy W. Yue ◽  
Michael Bower ◽  
Paul J. Ala ◽  
Brian Wayland ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Phosphatase Inhibitors ◽  
Protein Tyrosine

scholarly journals Protein phosphatase PP2C in the flagellum of Leishmania major: cloning and characterization

2017 ◽  
Vol 3 ◽  
Author(s):  
A. R. Escalona-Montaño ◽  
R. Pérez-Montfort ◽  
N. Cabrera ◽  
R. Mondragón-Flores ◽  
D. E. Vélez-Ramírez ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Protein Phosphatase ◽  
Protein Concentration ◽  
Leishmania Major ◽  
Polyclonal Antibodies ◽  
Divalent Cations ◽  
Tyrosine Phosphatase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Phosphatase Inhibitors

AbstractThe main goal of this work consisted in cloning, purifying and characterizing a protein phosphatase 2C (PP2C) from promastigotes ofLeishmania major. The gene was cloned and amplified by PCR using specific oligonucleotides and the recombinant protein was purified by affinity chromatography. The peak with maximal protein concentration was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and revealed a protein of 44·9 kDa with PP2C activity. This activity was dependent on divalent cations (Mg+2and Mn+2) and was optimal at pH of 8·5, using phosphothreonine as the substrate. Sanguinarine inhibited the activity of the recombinantLmPP2C, while protein tyrosine phosphatase inhibitors had no effect. The recombinantLmPP2C was used to generate polyclonal antibodies. These antibodies recognized a protein of 44·9 kDa in differentLeishmaniaspecies; theLmPP2C was localized in the flagellar pocket and the flagellum of promastigotes.

Sign in / Sign up

Export Citation Format

Share Document