scholarly journals Erratum: Corrigendum: The malaria parasite egress protease SUB1 is a calcium-dependent redox switch subtilisin

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Chrislaine Withers-Martinez ◽  
Malcolm Strath ◽  
Fiona Hackett ◽  
Lesley F. Haire ◽  
Steven A. Howell ◽  
...  
Keyword(s):  
Malaria Parasite ◽  
Calcium Dependent ◽  
Redox Switch ◽  
Parasite Egress

scholarly journals The malaria parasite egress protease SUB1 is a calcium-dependent redox switch subtilisin

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Chrislaine Withers-Martinez ◽  
Malcolm Strath ◽  
Fiona Hackett ◽  
Lesley F. Haire ◽  
Steven A. Howell ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Parasitophorous Vacuole ◽  
Protozoan Parasite ◽  
Crystallographic Structure ◽  
Disulphide Bridge ◽  
Calcium Dependent ◽  
Redox Switch ◽  
Scissile Bond ◽  
Parasite Egress

Abstract Malaria is caused by a protozoan parasite that replicates within an intraerythrocytic parasitophorous vacuole. Release (egress) of malaria merozoites from the host erythrocyte is a highly regulated and calcium-dependent event that is critical for disease progression. Minutes before egress, an essential parasite serine protease called SUB1 is discharged into the parasitophorous vacuole, where it proteolytically processes a subset of parasite proteins that play indispensable roles in egress and invasion. Here we report the first crystallographic structure of Plasmodium falciparum SUB1 at 2.25 Å, in complex with its cognate prodomain. The structure highlights the basis of the calcium dependence of SUB1, as well as its unusual requirement for interactions with substrate residues on both prime and non-prime sides of the scissile bond. Importantly, the structure also reveals the presence of a solvent-exposed redox-sensitive disulphide bridge, unique among the subtilisin family, that likely acts as a regulator of protease activity in the parasite.

scholarly journals Calcium-Dependent Protein Kinase 5 Is Required for Release of Egress-Specific Organelles in Plasmodium falciparum

mBio ◽  
2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Sabrina Absalon ◽  
Karin Blomqvist ◽  
Rachel M. Rudlaff ◽  
Travis J. DeLano ◽  
Michael P. Pollastri ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Kinase ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Malaria Parasite ◽  
Dependent Protein Kinase ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Parasite Egress ◽  
Calcium Dependent Protein Kinase

ABSTRACT The human malaria parasite Plasmodium falciparum requires efficient egress out of an infected red blood cell for pathogenesis. This egress event is highly coordinated and is mediated by several signaling proteins, including the plant-like P. falciparum calcium-dependent protein kinase 5 (PfCDPK5). Knockdown of PfCDPK5 results in an egress block where parasites are trapped inside their host cells. The mechanism of this PfCDPK5-dependent block, however, remains unknown. Here, we show that PfCDPK5 colocalizes with a specialized set of parasite organelles known as micronemes and is required for their discharge, implicating failure of this step as the cause of the egress defect in PfCDPK5-deficient parasites. Furthermore, we show that PfCDPK5 cooperates with the P. falciparum cGMP-dependent kinase (PfPKG) to fully activate the protease cascade critical for parasite egress. The PfCDPK5-dependent arrest can be overcome by hyperactivation of PfPKG or by physical disruption of the arrested parasite, and we show that both treatments facilitate the release of the micronemes required for egress. Our results define the molecular mechanism of PfCDPK5 function and elucidate the complex signaling pathway of parasite egress. IMPORTANCE The signs and symptoms of clinical malaria result from the replication of parasites in human blood. Efficient egress of the malaria parasite Plasmodium falciparum out of an infected red blood cell is critical for pathogenesis. The P. falciparum calcium-dependent protein kinase 5 (PfCDPK5) is essential for parasite egress. Following PfCDPK5 knockdown, parasites remain trapped inside their host cell and do not egress, but the mechanism for this block remains unknown. We show that PfCDPK5 colocalizes with parasite organelles known as micronemes. We demonstrate that PfCDPK5 is critical for the discharge of these micronemes and that failure of this step is the molecular mechanism of the parasite egress arrest. We also show that hyperactivation of the cGMP-dependent kinase PKG can overcome this arrest. Our data suggest that small molecules that inhibit the egress signaling pathway could be effective antimalarial therapeutics.

scholarly journals Overlapping and distinct roles of CDPK family members in the pre-erythrocytic cycle of the rodent malaria parasite, Plasmodium berghei

2019 ◽  
Author(s):  
K. Govindasamy ◽  
P. Bhanot
Keyword(s):  
Malaria Parasite ◽  
Liver Cells ◽  
Disease Symptoms ◽  
Calcium Dependent ◽  
Parasite Plasmodium ◽  
Erythrocytic Cycle ◽  
Dependent Protein ◽  
Chemical Inhibition ◽  
Cdpk Family ◽  
Parasite Egress

AbstractInvasion of, development within, and exit from hepatocytes by Plasmodium is essential for the parasite to establish the malaria-causing erythrocytic cycle. Identification of signaling pathways that operate during the pre-erythrocytic cycle provides insights into a critical stage of infection and potential targets for chemoprevention of disease. Calcium Dependent Protein Kinases (CDPK) represent a kinase family that is present in Plasmodium but absent in mammals. We demonstrate that P. berghei homologs of CDPK1, CDPK4 and CDPK5 play overlapping but distinct roles in sporozoite invasion and parasite egress from hepatocytes. All three kinases are expressed in sporozoites. All three are required for optimal motility of sporozoites and consequently their invasion of hepatocytes. Increased cGMP compensates for the functional loss of CDPK1 and CDPK5 during sporozoite invasion but cannot overcome CDPK4’s loss. CDPK1 and CDPK5 expression is downregulated after sporozoite invasion. CDPK5 reappears in a subset of late stage liver stages and is present in all merosomes. Chemical inhibition of CDPK4 and depletion of CDPK5 in liver stages suggests that these kinases play a role in the formation and/or release of merosomes from mature liver stages. Furthermore, depletion of CDPK5 in merosomes significantly delays a merosome-initiated erythrocytic cycle without affecting the infectivity of hepatic merozoites. These data suggest that CDPK5 is required for the release of hepatic merozoites from merosomes. Our work provides the first evidence that sporozoite invasion requires CDPK1 and CDPK5 and that the release of hepatic merozoites is a regulated process.SignificanceThe malaria-parasite Plasmodium begins its mammalian cycle by infecting hepatocytes in the liver. A single parasite differentiates into tens of thousands of hepatic merozoites which exit the host cell in vesicles called merosomes. Hepatic merozoites initiate the first round of erythrocytic infection that leads to disease symptoms. We show that optimal invasion of liver cells by Plasmodium requires the action of three closely-related parasite kinases, CDPK1, 4 and 5. Loss of any of the three enzymes in the parasite significantly reduces infection of liver cells. CDPK5 is also required for the release of hepatic merozoites from merosomes and therefore for initiating the erythrocytic cycle. A better understanding of how these kinases function could lead to drugs that prevent malaria.

scholarly journals Cytoplasmic free Ca2+ is essential for multiple steps in malaria parasite egress from infected erythrocytes

2013 ◽  
Vol 12 (1) ◽  
pp. 41 ◽  
Author(s):  
Svetlana Glushakova ◽  
Vladimir Lizunov ◽  
Paul S Blank ◽  
Kamran Melikov ◽  
Glen Humphrey ◽  
...  
Keyword(s):  
Malaria Parasite ◽  
Parasite Egress

scholarly journals Cryptosporidium parvum Subtilisin-Like Serine Protease (SUB1) Is Crucial for Parasite Egress from Host Cells

2019 ◽  
Vol 87 (5) ◽  
Author(s):  
Samantha Nava ◽  
A. Clinton White ◽  
Alejandro Castellanos-González
Keyword(s):  
Life Cycle ◽  
Serine Protease ◽  
Host Cells ◽  
Effective Vaccine ◽  
Infection Model ◽  
Target Cells ◽  
Calcium Dependent ◽  
Argonaute 2 ◽  
Parasite Egress

ABSTRACT Despite the severity and global burden of Cryptosporidium infection, treatments are less than optimal, and there is no effective vaccine. Egress from host cells is a key process for the completion of the life cycle of apicomplexan parasites. For Plasmodium species, subtilisin-like serine protease (SUB1) is a key mediator of egress. For Toxoplasma species, calcium-dependent protein kinases (CDPKs) are critical. In this study, we characterized Cryptosporidium SUB1 expression and evaluated its effect using an infection model. We found increased expression between 12 and 20 h after in vitro infection, prior to egress. We induced silencing of SUB1 (ΔSUB1) mRNA using SUB1 single-stranded antisense RNA coupled with human Argonaute 2. Silencing of SUB1 mRNA expression did not affect parasite viability, excystation, or invasion of target cells. However, knockdown led to a 95% decrease in the proportion of released merozoites in vitro (P < 0.0001). In contrast, silencing of CDPK5 had no effect on egress. Overall, our results indicate that SUB1 is a key mediator of Cryptosporidium egress and suggest that interruption of the life cycle at this stage may effectively inhibit the propagation of infection.

scholarly journals New Stages in the Program of Malaria Parasite Egress Imaged in Normal and Sickle Erythrocytes

2010 ◽  
Vol 20 (12) ◽  
pp. 1117-1121 ◽  
Author(s):  
Svetlana Glushakova ◽  
Glen Humphrey ◽  
Evgenia Leikina ◽  
Amanda Balaban ◽  
Jeffrey Miller ◽  
...  
Keyword(s):  
Malaria Parasite ◽  
Sickle Erythrocytes ◽  
Parasite Egress

scholarly journals The Plasmodium falciparum pseudoprotease SERA5 regulates the kinetics and efficiency of malaria parasite egress from host erythrocytes

2017 ◽  
Vol 13 (7) ◽  
pp. e1006453 ◽  
Author(s):  
Christine R. Collins ◽  
Fiona Hackett ◽  
Jonathan Atid ◽  
Michele Ser Ying Tan ◽  
Michael J. Blackman
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Parasite Egress
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