scholarly journals Helices on Interdomain Interface Couple Catalysis in the ATPPase Domain with Allostery in Plasmodium falciparum GMP Synthetase

ChemBioChem ◽  
2020 ◽  
Vol 21 (19) ◽  
pp. 2805-2817
Author(s):  
Santosh Shivakumaraswamy ◽  
Nivedita Pandey ◽  
Lionel Ballut ◽  
Sébastien Violot ◽  
Nushin Aghajari ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Gmp Synthetase

scholarly journals Helices on interdomain interface couple catalysis in the ATPPase domain with allostery in Plasmodium falciparum GMP synthetase

2019 ◽  
Author(s):  
Santosh Shivakumaraswamy ◽  
Nivedita Pandey ◽  
Lionel Ballut ◽  
Sébastien Violot ◽  
Nushin Aghajari ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Basis ◽  
Drug Targets ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Allosteric Activation ◽  
Purine Base ◽  
Interdomain Interactions ◽  
Hydrolysis Of ◽  
Gmp Synthetase

AbstractGMP synthetase catalyzes the substitution of the C2 oxo-group of the purine base in XMP with an amino-group generating GMP, the last step in the biosynthesis of GMP. This reaction involves a series of catalytic events that include hydrolysis of Gln generating ammonia in the glutamine amidotransferase (GATase) domain, activation of XMP to adenyl-XMP intermediate in the ATP pyrophosphatase (ATPPase) domain and reaction of ammonia with the intermediate to generate GMP. Inherent to the functioning of GMP synthetases is bidirectional domain crosstalk, which leads to allosteric activation of the GATase domain by substrates binding to the ATPPase domain, synchronization of the two catalytic events and tunnelling of ammonia from the GATase to the ATPPase domain. Herein, we have taken recourse to the analysis of structures of GMP synthetases, site-directed mutagenesis and, steady-state and transient kinetic assays on the Plasmodium falciparum enzyme to decipher the molecular basis of catalysis in the ATPPase domain and domain crosstalk. The results map the residues critical for catalysis in the ATPPase domain to the helices α11 and α12 that are located at the interdomain interface, and the lid-loop that follows α11. This apart, perturbing interdomain interactions involving residues on α11 and α12 impairs GATase activation. These results imply that this arrangement of helices at the domain interface with residues that play roles in ATPPase catalysis as well as domain crosstalk enables coupling ATPPase catalysis with GATase activation. Overall, the study enhances our understanding of GMP synthetases, which are drug targets in many infectious pathogens.

scholarly journals Active site coupling in Plasmodium falciparum GMP synthetase is triggered by domain rotation

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Lionel Ballut ◽  
Sébastien Violot ◽  
Santosh Shivakumaraswamy ◽  
Lakshmi Prasoona Thota ◽  
Manu Sathya ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Active Site ◽  
Gmp Synthetase ◽  
Domain Rotation

Kinetic and biochemical characterization of Plasmodium falciparum GMP synthetase

2007 ◽  
Vol 409 (1) ◽  
pp. 263-273 ◽  
Author(s):  
Javaid Yousuf Bhat ◽  
Brahmanaspati Ganapathi Shastri ◽  
Hemalatha Balaram
Keyword(s):  
Plasmodium Falciparum ◽  
Biochemical Characterization ◽  
Kinetic Mechanism ◽  
Ligand Specificity ◽  
Nucleotide Analogues ◽  
Ping Pong ◽  
Fatal Form ◽  
Random Manner ◽  
Gmp Synthetase

Plasmodium falciparum, the causative agent of the fatal form of malaria, synthesizes GMP primarily from IMP and, hence, needs active GMPS (GMP synthetase) for its survival. GMPS, a G-type amidotransferase, catalyses the amination of XMP to GMP with the reaction occurring in two domains, the GAT (glutamine amidotransferase) and ATPPase (ATP pyrophosphatase). The GAT domain hydrolyses glutamine to glutamate and ammonia, while the ATPPase domain catalyses the formation of the intermediate AMP-XMP from ATP and XMP. Co-ordination of activity across the two domains, achieved through channelling of ammonia from GAT to the effector domain, is the hallmark of amidotransferases. Our studies aimed at understanding the kinetic mechanism of PfGMPS (Plasmodium falciparum GMPS) indicated steady-state ordered binding of ATP followed by XMP to the ATPPase domain with glutamine binding in a random manner to the GAT domain. We attribute the irreversible, Ping Pong step seen in initial velocity kinetics to the release of glutamate before the attack of the adenyl-XMP intermediate by ammonia. Specific aspects of the overall kinetic mechanism of PfGMPS are different from that reported for the human and Escherichia coli enzymes. Unlike human GMPS, absence of tight co-ordination of activity across the two domains was evident in the parasite enzyme. Variations seen in the inhibition by nucleosides and nucleotide analogues between human GMPS and PfGMPS highlighted differences in ligand specificity that could serve as a basis for the design of specific inhibitors. The present study represents the first report on recombinant His-tagged GMPS from parasitic protozoa.

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

Platelet Hypersensitivity in Acute Malaria (Plasmodium falciparum) Infection in Man

1981 ◽  
Vol 46 (02) ◽  
pp. 547-549 ◽  
Author(s):  
E M Essien ◽  
M I Ebhota
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Infection ◽  
Light Transmission ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Wave Pattern ◽  
Falciparum Infection ◽  
Secondary Wave ◽  
Control Subjects ◽  
The Mean

SummaryDuring acute malaria infection, platelets in human platelet-rich plasma are hypersensitive to the addition of ADP between 1.0 uM and 5.0 uM, or adrenaline 0.11 uM as aggregating agents. The mean maximum aggregation amplitude (as % of light transmission) obtained from 8 subjects in response to added ADP (1.0 uM), 39.8 ± 27 (1SD), was significantly greater than the value in 6 controls (5.2±6.7 (1SD); t = 3, 51 P <0.005). A similar pattern of response was obtained with higher ADP concentrations (2.4,4.5 or 5.0 uM) in 22 patients and 20 control subjects (89.9±14.9% vs 77.8±16.5% (1SD) t = 2.45, P <0.02). Addition of 4.5 uM ADP to patient PRP usually evoked only a single aggregation wave (fused primary and secondary waves) while the typical primary and secondary wave pattern was usually obtained from controls.Mean plasma B-thromboglobulin (BTG) concentration in 7 patients (208.3 ± 15.6 ng/ml) was significantly higher than the value in 6 control subjects (59.2±15.7 ng/ml; t = 13.44, P <0.002).

Durch Vektoren übertragene Erkrankungen

2018 ◽  
Vol 18 (05) ◽  
pp. 332-338
Author(s):  
C. Kleine ◽  
U. Ziegler ◽  
E.-M. Schwienhorst ◽  
A. Stich
Keyword(s):  
Plasmodium Falciparum ◽  
Sich Eine ◽  
Malaria Tropica

ZusammenfassungDer folgende Artikel fokussiert auf Erkrankungen, deren Erreger von Vektoren (Insekten, Spinnentieren) aktiv auf den Menschen übertragen werden. Sie spielen in tropischen und subtropischen Regionen der Erde eine erhebliche Rolle und sind auch im Rahmen der Differenzialdiagnose bei kranken Reiserückkehrern von großer Bedeutung. Am wichtigsten ist die Malaria, insbesondere die lebensbedrohliche Malaria tropica durch Plasmodium falciparum. Jede fieberhafte Erkrankung aus den Tropen erfordert eine zeitnahe Malaria-Diagnostik. Tropische Viruserkrankungen durch Dengue-, West-Nil-, Chikungunya- oder Zika-Viren haben sich in den vergangenen Jahrzehnten massiv ausgebreitet und stellen auch eine zunehmende Bedrohung für den europäischen Raum dar. Andere Vektor-übertragene Erkrankungen sind zwar von großer lokaler Relevanz in endemischen Regionen, aber als importierte Infektionen in Deutschland relativ selten. Bei der Betreuung der Patienten empfiehlt sich eine enge Kooperation mit Tropenmedizinern.

Prevalence of Plasmodium falciparum and Salmonella typhi Infection and Coinfection and Their Association With Fever in Northern Tanzania

2018 ◽  
Vol 2 (2) ◽  
pp. 147-155
Author(s):  
Jaffu Chilongola ◽  
Sophia Kombe ◽  
Pius Horumpende ◽  
Rebeka Nazareth ◽  
Elias Sabuni ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Salmonella Typhi ◽  
Northern Tanzania
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