scholarly journals Pyroglutamyl peptidase type I from Trypanosoma brucei: a new virulence factor from African trypanosomes that de-blocks regulatory peptides in the plasma of infected hosts

2006 ◽  
Vol 394 (3) ◽  
pp. 635-645 ◽  
Author(s):  
Rory E. Morty ◽  
Patrick Bulau ◽  
Roger Pellé ◽  
Sherwin Wilk ◽  
Koji Abe
Keyword(s):  
Trypanosoma Brucei ◽  
Half Life ◽  
Specific Inhibitor ◽  
Parasitic Infections ◽  
Type I ◽  
African Trypanosomiasis ◽  
Thyrotrophin Releasing Hormone ◽  
African Trypanosomes ◽  
Releasing Hormone ◽  
Plasma Half Life

Peptidases of parasitic protozoans are emerging as novel virulence factors and therapeutic targets in parasitic infections. A trypanosome-derived aminopeptidase that exclusively hydrolysed substrates with Glp (pyroglutamic acid) in P1 was purified 9248-fold from the plasma of rats infected with Trypanosoma brucei brucei. The enzyme responsible was cloned from a T. brucei brucei genomic DNA library and identified as type I PGP (pyroglutamyl peptidase), belonging to the C15 family of cysteine peptidases. We showed that PGP is expressed in all life cycle stages of T. brucei brucei and is expressed in four other blood-stream-form African trypanosomes. Trypanosome PGP was optimally active and stable at bloodstream pH, and was insensitive to host plasma cysteine peptidase inhibitors. Native purified and recombinant hyper-expressed trypanosome PGP removed the N-terminal Glp blocking groups from TRH (thyrotrophin-releasing hormone) and GnRH (gonadotropin-releasing hormone) with a kcat/Km value of 0.5 and 0.1 s−1·μM−1 respectively. The half-life of TRH and GnRH was dramatically reduced in the plasma of trypanosome-infected rats, both in vitro and in vivo. Employing an activity-neutralizing anti-trypanosome PGP antibody, and pyroglutamyl diazomethyl ketone, a specific inhibitor of type I PGP, we demonstrated that trypanosome PGP is entirely responsible for the reduced plasma half-life of TRH, and partially responsible for the reduced plasma half-life of GnRH in a rodent model of African trypanosomiasis. The abnormal degradation of TRH and GnRH, and perhaps other neuropeptides N-terminally blocked with a pyroglutamyl moiety, by trypanosome PGP, may contribute to some of the endocrine lesions observed in African trypanosomiasis.

scholarly journals p67: a cryptic lysosomal hydrolase in Trypanosoma brucei?

Parasitology ◽  
2020 ◽  
pp. 1-6
Author(s):  
Carolina M. Koeller ◽  
Terry K. Smith ◽  
Andrew M. Gulick ◽  
James D. Bangs
Keyword(s):  
Trypanosoma Brucei ◽  
Peptide Bond ◽  
Parasitic Infections ◽  
Type I ◽  
Lysosomal Hydrolase ◽  
African Trypanosomes ◽  
Founding Member ◽  
Transmembrane Glycoprotein ◽  
Subsequent Hydrolysis ◽  
Processing Pathways

Abstract p67 is a type I transmembrane glycoprotein of the terminal lysosome of African trypanosomes. Its biosynthesis involves transport of an initial gp100 ER precursor to the lysosome, followed by cleavage to N-terminal (gp32) and C-terminal (gp42) subunits that remain non-covalently associated. p67 knockdown is lethal, but the only overt phenotype is an enlarged lysosome (~250 to >1000 nm). Orthologues have been characterized in Dictyostelium and mammals. These have processing pathways similar to p67, and are thought to have phospholipase B-like (PLBL) activity. The mouse PLBD2 crystal structure revealed that the PLBLs represent a subgroup of the larger N-terminal nucleophile (NTN) superfamily, all of which are hydrolases. NTNs activate by internal autocleavage mediated by a nucleophilic residue, i.e. Cys, Ser or Thr, on the upstream peptide bond to form N-terminal α (gp32) and C-terminal β (gp42) subunits that remain non-covalently associated. The N-terminal residue of the β subunit is then catalytic in subsequent hydrolysis reactions. All PLBLs have a conserved Cys/Ser dipeptide at the α/β junction (Cys241/Ser242 in p67), mutation of which renders p67 non-functional in RNAi rescue assays. p67 orthologues are found in many clades of parasitic protozoa, thus p67 is the founding member of a group of hydrolases that likely play a role broadly in the pathogenesis of parasitic infections.

scholarly journals Trypanosoma brucei J-Protein 2 Functionally Co-Operates with the Cytosolic Hsp70 and Hsp70.4 Proteins

2019 ◽  
Vol 20 (23) ◽  
pp. 5843 ◽  
Author(s):  
Stephen John Bentley ◽  
Aileen Boshoff
Keyword(s):  
Heat Shock ◽  
Trypanosoma Brucei ◽  
Therapeutic Strategies ◽  
Type I ◽  
Protein Homeostasis ◽  
African Trypanosomiasis ◽  
Wide Range ◽  
Shock Proteins ◽  
Insight Into ◽  
J Protein

The etiological agent of African trypanosomiasis, Trypanosoma brucei (Tb), has been identified to possess an expanded and diverse group of heat shock proteins, which have been implicated in cytoprotection, differentiation, and subsequently progression and transmission of the disease. Heat shock protein 70 (Hsp70) is a highly conserved and ubiquitous molecular chaperone that is important in maintaining protein homeostasis in the cell. Its function is regulated by a wide range of co-chaperones, and inhibition of these functions and interactions with co-chaperones are emerging as potential therapeutic targets for numerous diseases. This study sought to biochemically characterize the cytosolic TbHsp70 and TbHsp70.4 proteins and to investigate if they functionally co-operate with the Type I J-protein, Tbj2. Expression of TbHsp70 was shown to be heat inducible, while TbHsp70.4 was constitutively expressed. The basal ATPase activities of TbHsp70.4 and TbHsp70 were stimulated by Tbj2. It was further determined that Tbj2 functionally co-operated with TbHsp70 and TbHsp70.4 as the J-protein was shown to stimulate the ability of both proteins to mediate the refolding of chemically denatured β-galactosidase. This study provides further insight into this important class of proteins, which may contribute to the development of new therapeutic strategies to combat African Trypanosomiasis.

scholarly journals Enhancedin VivoEfficacy of a Type I Interferon Superagonist with Extended Plasma Half-life in a Mouse Model of Multiple Sclerosis

2014 ◽  
Vol 289 (42) ◽  
pp. 29014-29029 ◽  
Author(s):  
Daniel Harari ◽  
Nadine Kuhn ◽  
Renne Abramovich ◽  
Keren Sasson ◽  
Alla L. Zozulya ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Mouse Model ◽  
Half Life ◽  
Type I Interferon ◽  
Type I ◽  
Extended Plasma ◽  
Plasma Half Life

scholarly journals Trypanosoma bruceiJ protein 2 functionally cooperates with the cytosolic Hsp70.4 and Hsp70 proteins

2019 ◽  
Author(s):  
Stephen J. Bentley ◽  
Aileen Boshoff
Keyword(s):  
Heat Shock ◽  
Trypanosoma Brucei ◽  
Therapeutic Strategies ◽  
Type I ◽  
Protein Homeostasis ◽  
African Trypanosomiasis ◽  
Wide Range ◽  
Shock Proteins ◽  
Insight Into ◽  
J Protein

AbstractThe etiological agent of African trypanosomiasis,Trypanosoma brucei, has been identified to possess an expanded and diverse group of heat shock proteins, that have been implicated in cytoprotection, differentiation, and subsequently progression and transmission of the disease. Heat shock protein 70 is a highly conserved and ubiquitous molecular chaperone that is important in maintaining protein homeostasis in the cell. Its function is regulated by a wide range of co-chaperones; and inhibition of these functions and interactions with co-chaperones are emerging as potential therapeutic targets for numerous diseases. This study sought to biochemically characterize the cytosolic Hsp70 and Hsp70.4 proteins and to investigate if they form a functional partnership with the Type I J-protein, Tbj2. The cytosolic localisation of the proteins was confirmed by accessing the TrypTag endogenous tagging microscopy database. Expression of TbHsp70 was shown to be heat inducible, whilst TbHsp70.4 was constitutively expressed. The basal ATPase activities of TbHsp70.4 and TbHsp70 were stimulated by Tbj2. It was further determined that Tbj2 forms a functional partnership with TbHsp70 and TbHsp70.4 as the J-protein was shown to stimulate the ability of both proteins to mediate the refolding of chemically denatured β-galactosidase. This study provides further insight into this important class of proteins which may contribute to the development of new therapeutic strategies to combat African Trypanosomiasis.

Covalent Complexes Between Low Molecular Weight Heparin Fragments and Antithrombin III – Inhibition Kinetics and Turnover Parameters

1983 ◽  
Vol 49 (02) ◽  
pp. 109-115 ◽  
Author(s):  
M Hoylaerts ◽  
E Holmer ◽  
M de Mol ◽  
D Collen
Keyword(s):  
Molecular Weight ◽  
Half Life ◽  
Low Molecular Weight Heparin ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Life Time ◽  
Low Molecular Weight ◽  
High Affinity ◽  
Plasma Half Life ◽  
Covalent Complex

SummaryTwo high affinity heparin fragments (A/r 4,300 and M, 3,200) were covalently coupled to antithrombin III (J. Biol. Chem. 1982; 257: 3401-3408) with an apparent 1:1 stoichiometry and a 30-35% yield.The purified covalent complexes inhibited factor Xa with second order rate constants very similar to those obtained for antithrombin III saturated with these heparin fragments and to that obtained for the covalent complex between antithrombin III and native high affinity heparin.The disappearance rates from plasma in rabbits of both low molecular weight heparin fragments and their complexes could adequately be represented by two-compartment mammillary models. The plasma half-life (t'/j) of both low Afr-heparin fragments was approximately 2.4 hr. Covalent coupling of the fragments to antithrombin III increased this half-life about 3.5 fold (t1/2 ≃ 7.7 hr), approaching that of free antithrombin III (t1/2 ≃ 11 ± 0.4 hr) and resulting in a 30fold longer life time of factor Xa inhibitory activity in plasma as compared to that of free intact heparin (t1/2 ≃ 0.25 ± 0.04 hr).

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

DIE WIRKUNG VON SYNTHETISCHEM THYROTROPHIN RELEASING HORMONE AUF DIE ENTWICKLUNG EINES EXPERIMENTELLEN EXOPHTHALMUS BEIM GOLDFISCH

1971 ◽  
Vol 68 (2) ◽  
pp. 363-366 ◽  
Author(s):  
W. Wildmeister ◽  
F. A. Horster
Keyword(s):  
Carassius Auratus ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone

ABSTRACT Gold-fishes (carassius auratus) were injected with synthetic thyrotrophin releasing hormone (TRH) in concentrations of 25 μg to 1000 μg/fish. TRH did not provoke endocrine exophthalmos.

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