scholarly journals Cholesterol bound Plasmodium falciparum co-chaperone ‘PFA0660w’ complexes with major virulence factor ‘PfEMP1’ via chaperone ‘PfHsp70-x’

2018 ◽  
Author(s):  
Ankita Behl ◽  
Vikash Kumar ◽  
Anjali Bisht ◽  
Jiban J. Panda ◽  
Rachna Hora ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Direct Interaction ◽  
Lipid Binding ◽  
The Novel ◽  
The Past ◽  
Biochemical Assays ◽  
Erythrocyte Surface ◽  
Parasite Survival

AbstractLethality of Plasmodium falciparum (Pf) caused malaria results from ‘cytoadherence’, which is effected by exported Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. Several exported Pf proteins (exportome) including chaperones alongside cholesterol rich microdomains are crucial for PfEMP1 translocation to infected erythrocyte surface. An exported Hsp40 (heat shock protein 40) ‘PFA0660w’ functions as a co-chaperone of ‘PfHsp70-x’, and these co-localize to specialized intracellular mobile structures termed J-dots. Our studies attempt to understand the function of PFA0660w-PfHsp70-x chaperone pair using recombinant proteins. Biochemical assays reveal that N and C-terminal domains of PFA0660w and PfHsp70-x respectively are critical for their activity. We show the novel direct interaction of PfHsp70-x with the cytoplasmic tail of PfEMP1, and binding of PFA0660w with cholesterol. PFA0660w operates both as a chaperone and lipid binding molecule via its separate substrate and cholesterol binding sites. PfHsp70-x binds cholesterol linked PFA0660w and PfEMP1 simultaneously in vitro to form a complex. Collectively, our results and the past literature support the hypothesis that PFA0660w-PfHsp70-x chaperone pair assists PfEMP1 transport across the host erythrocyte through cholesterol containing ‘J-dots’. Since PFA0660w seems essential for parasite survival, characterization of its interaction with PfHsp70-x and J-dots may form the basis for development of future antimalarials.

Formation, translocation and resolution of Holliday junctions during homologous genetic recombination

1995 ◽  
Vol 347 (1319) ◽  
pp. 21-25 ◽  
Keyword(s):  
Molecular Mechanisms ◽  
Genetic Recombination ◽  
Holliday Junctions ◽  
The Novel ◽  
E Coli ◽  
The Past ◽  
Endonucleolytic Cleavage ◽  
Insight Into ◽  
Made In

Over the past three or four years, great strides have been made in our understanding of the proteins involved in recombination and the mechanisms by which recombinant molecules are formed. This review summarizes our current understanding of the process by focusing on recent studies of proteins involved in the later steps of recombination in bacteria. In particular, biochemical investigation of the in vitro properties of the E. coli RuvA, RuvB and RuvC proteins have provided our first insight into the novel molecular mechanisms by which Holliday junctions are moved along DNA and then resolved by endonucleolytic cleavage.

scholarly journals Chemical Derivatization and Characterization of Novel Antitrypanosomals for African Trypanosomiasis

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4488
Author(s):  
Aboagye Kwarteng Dofuor ◽  
Temitayo Samson Ademolue ◽  
Cynthia Mmalebna Amisigo ◽  
Kwaku Kyeremeh ◽  
Theresa Manful Gwira
Keyword(s):  
Structural Modification ◽  
Spectroscopic Analysis ◽  
Microscopic Analysis ◽  
The Novel ◽  
Chemical Derivatization ◽  
African Trypanosomiasis ◽  
Chemical Structures ◽  
Normal Ratio

The search for novel antitrypanosomals and the investigation into their mode of action remain crucial due to the toxicity and resistance of commercially available antitrypanosomal drugs. In this study, two novel antitrypanosomals, tortodofuordioxamide (compound 2) and tortodofuorpyramide (compound 3), were chemically derived from the natural N-alkylamide tortozanthoxylamide (compound 1) through structural modification. The chemical structures of these compounds were confirmed through spectrometric and spectroscopic analysis, and their in vitro efficacy and possible mechanisms of action were, subsequently, investigated in Trypanosoma brucei (T. brucei), one of the causative species of African trypanosomiasis (AT). The novel compounds 2 and 3 displayed significant antitrypanosomal potencies in terms of half-maximal effective concentrations (EC50) and selectivity indices (SI) (compound 1, EC50 = 7.3 μM, SI = 29.5; compound 2, EC50 = 3.2 μM, SI = 91.3; compound 3, EC50 = 4.5 μM, SI = 69.9). Microscopic analysis indicated that at the EC50 values, the compounds resulted in the coiling and clumping of parasite subpopulations without significantly affecting the normal ratio of nuclei to kinetoplasts. In contrast to the animal antitrypanosomal drug diminazene, compounds 1, 2 and 3 exhibited antioxidant absorbance properties comparable to the standard antioxidant Trolox (Trolox, 0.11 A; diminazene, 0.50 A; compound 1, 0.10 A; compound 2, 0.09 A; compound 3, 0.11 A). The analysis of growth kinetics suggested that the compounds exhibited a relatively gradual but consistent growth inhibition of T. brucei at different concentrations. The results suggest that further pharmacological optimization of compounds 2 and 3 may facilitate their development into novel AT chemotherapy.

scholarly journals A NewIn VivoModel System to Assess the Toxicity of Semiconductor Nanocrystals

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Angela Tino ◽  
Alfredo Ambrosone ◽  
Lucia Mattera ◽  
Valentina Marchesano ◽  
Andrei Susha ◽  
...  
Keyword(s):  
Semiconductor Nanocrystals ◽  
Minimal Risk ◽  
The Novel ◽  
Toxicological Evaluation ◽  
Hydra Vulgaris ◽  
Population Growth Rates ◽  
Single Structure

In the emerging area of nanotechnology, a key issue is related to the potential impacts of the novel nanomaterials on the environment and human health, so that this technology can be used with minimal risk. Specifically designed to combine on a single structure multipurpose tags and properties, smart nanomaterials need a comprehensive characterization of both chemicophysical properties and adequate toxicological evaluation, which is a challenging endeavour; thein vitrotoxicity assays that are often employed for nanotoxicity assessments do not accurately predictin vivoresponse. To overcome these limitations and to evaluate toxicity characteristics of cadmium telluride quantum dots in relation to surface coatings, we have employed the freshwater polypHydra vulgarisas a model system. We assessedin vivoacute and sublethal toxicity by scoring for alteration of morphological traits, population growth rates, and influence on the regenerative capabilities providing new investigation clues for nanotoxicology purposes.

scholarly journals The endogenous galactofuranosidase GlfH1 hydrolyzes mycobacterial arabinogalactan

2020 ◽  
Vol 295 (15) ◽  
pp. 5110-5123 ◽  
Author(s):  
Lin Shen ◽  
Albertus Viljoen ◽  
Sydney Villaume ◽  
Maju Joe ◽  
Iman Halloum ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Changes ◽  
Cell Envelope ◽  
Wall Structure ◽  
Tubercle Bacillus ◽  
Bioinformatics Analyses ◽  
The Past ◽  
Biochemical Assays ◽  
Mycobacterial Protein

Despite impressive progress made over the past 20 years in our understanding of mycolylarabinogalactan-peptidoglycan (mAGP) biogenesis, the mechanisms by which the tubercle bacillus Mycobacterium tuberculosis adapts its cell wall structure and composition to various environmental conditions, especially during infection, remain poorly understood. Being the central portion of the mAGP complex, arabinogalactan (AG) is believed to be the constituent of the mycobacterial cell envelope that undergoes the least structural changes, but no reports exist supporting this assumption. Herein, using recombinantly expressed mycobacterial protein, bioinformatics analyses, and kinetic and biochemical assays, we demonstrate that the AG can be remodeled by a mycobacterial endogenous enzyme. In particular, we found that the mycobacterial GlfH1 (Rv3096) protein exhibits exo-β-d-galactofuranose hydrolase activity and is capable of hydrolyzing the galactan chain of AG by recurrent cleavage of the terminal β-(1,5) and β-(1,6)-Galf linkages. The characterization of this galactosidase represents a first step toward understanding the remodeling of mycobacterial AG.

scholarly journals Ubiquinone Biosynthesis over the Entire O2Range: Characterization of a Conserved O2-Independent Pathway

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Ludovic Pelosi ◽  
Chau-Duy-Tam Vo ◽  
Sophie Saphia Abby ◽  
Laurent Loiseau ◽  
Bérengère Rascalou ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Lipid Binding ◽  
The Novel ◽  
Human Pathogens ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Metabolic Plasticity ◽  
Accessory Factor ◽  
Cellular Bioenergetics

ABSTRACTMost bacteria can generate ATP by respiratory metabolism, in which electrons are shuttled from reduced substrates to terminal electron acceptors, via quinone molecules like ubiquinone. Dioxygen (O2) is the terminal electron acceptor of aerobic respiration and serves as a co-substrate in the biosynthesis of ubiquinone. Here, we characterize a novel, O2-independent pathway for the biosynthesis of ubiquinone. This pathway relies on three proteins, UbiT (YhbT), UbiU (YhbU), and UbiV (YhbV). UbiT contains an SCP2 lipid-binding domain and is likely an accessory factor of the biosynthetic pathway, while UbiU and UbiV (UbiU-UbiV) are involved in hydroxylation reactions and represent a novel class of O2-independent hydroxylases. We demonstrate that UbiU-UbiV form a heterodimer, wherein each protein binds a 4Fe-4S cluster via conserved cysteines that are essential for activity. The UbiT, -U, and -V proteins are found in alpha-, beta-, and gammaproteobacterial clades, including several human pathogens, supporting the widespread distribution of a previously unrecognized capacity to synthesize ubiquinone in the absence of O2. Together, the O2-dependent and O2-independent ubiquinone biosynthesis pathways contribute to optimizing bacterial metabolism over the entire O2range.IMPORTANCEIn order to colonize environments with large O2gradients or fluctuating O2levels, bacteria have developed metabolic responses that remain incompletely understood. Such adaptations have been recently linked to antibiotic resistance, virulence, and the capacity to develop in complex ecosystems like the microbiota. Here, we identify a novel pathway for the biosynthesis of ubiquinone, a molecule with a key role in cellular bioenergetics. We link three uncharacterized genes ofEscherichia colito this pathway and show that the pathway functions independently from O2. In contrast, the long-described pathway for ubiquinone biosynthesis requires O2as a substrate. In fact, we find that many proteobacteria are equipped with the O2-dependent and O2-independent pathways, supporting that they are able to synthesize ubiquinone over the entire O2range. Overall, we propose that the novel O2-independent pathway is part of the metabolic plasticity developed by proteobacteria to face various environmental O2levels.

scholarly journals Dysbindin deficiency Alters Cardiac BLOC-1 Complex and Myozap Levels in Mice

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2390
Author(s):  
Ankush Borlepawar ◽  
Nesrin Schmiedel ◽  
Matthias Eden ◽  
Lynn Christen ◽  
Alexandra Rosskopf ◽  
...  
Keyword(s):  
Direct Interaction ◽  
Cardiomyocyte Hypertrophy ◽  
Loss Of Function ◽  
Interaction Partners ◽  
Lysosome Related Organelles ◽  
The Stability ◽  
Schizophrenia Susceptibility

Dysbindin, a schizophrenia susceptibility marker and an essential constituent of BLOC-1 (biogenesis of lysosome-related organelles complex-1), has recently been associated with cardiomyocyte hypertrophy through the activation of Myozap-RhoA-mediated SRF signaling. We employed sandy mice (Dtnbp1_KO), which completely lack Dysbindin protein because of a spontaneous deletion of introns 5–7 of the Dtnbp1 gene, for pathophysiological characterization of the heart. Unlike in vitro, the loss-of-function of Dysbindin did not attenuate cardiac hypertrophy, either in response to transverse aortic constriction stress or upon phenylephrine treatment. Interestingly, however, the levels of hypertrophy-inducing interaction partner Myozap as well as the BLOC-1 partners of Dysbindin like Muted and Pallidin were dramatically reduced in Dtnbp1_KO mouse hearts. Taken together, our data suggest that Dysbindin’s role in cardiomyocyte hypertrophy is redundant in vivo, yet essential to maintain the stability of its direct interaction partners like Myozap, Pallidin and Muted.

scholarly journals Screening Assays for Epigenetic Targets Using Native Histones as Substrates

2011 ◽  
Vol 17 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Alexander-Thomas Hauser ◽  
Elisabeth-Maria Bissinger ◽  
Eric Metzger ◽  
Antje Repenning ◽  
Uta-Maria Bauer ◽  
...  
Keyword(s):  
In Vitro Assays ◽  
The Past ◽  
Chemistry Research ◽  
Core Histones ◽  
Homogeneous Assay ◽  
Screening Assays ◽  
Set Up ◽  
Identification And Characterization

In the past years, a lot of attention has been given to the identification and characterization of selective and potent inhibitors of chromatin-modifying enzymes to better understand their specific role in transcriptional regulation. As aberrant histone methylation is involved in different pathological processes, the search for methyltransferase and demethylase inhibitors has emerged as a crucial issue in current medicinal chemistry research. High-throughput in vitro assays are important tools for the identification of new methyltransferase or demethylase inhibitors. These usually use oligopeptide substrates derived from histone sequences, although in many cases, they are not good substrates for these enzymes. Here, the authors report about the setup and establishment of in vitro assays that use native core histones as substrates, enabling an assay environment that better resembles native conditions. They have applied these substrates for the known formaldehyde dehydrogenase assay for the histone demethylase LSD1 and have established two new antibody-based assays. For LSD1, a heterogeneous assay format was set up, and a homogeneous assay was used for the characterization of the arginine methyltransferase PRMT1. Validation of the system was achieved with reference inhibitors in each case.

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