Biology subjects

Dapper, C.

Publications and source records attributed to Dapper, C..

3 recordsLinked to original sources

bioRxiv2025

Defining the minimal enzymatic requirements for fatty acid scavenging from lysophosphatidylcholine by erythrocytic Plasmodium falciparum

Host-derived lysophosphatidylcholine (LPC) is a significant source of choline and fatty acids for the intraerythrocytic malaria parasite Plasmodium falciparum. Two lysophospholipases play a dominant role in LPC catabolism: exported lipase 2 (XL2) and exported lipase homolog 4 (XLH4). Loss of these two enzymes greatly reduces, but does not abrogate, the parasites ability to utilize LPC as a source of fatty acids. In this study, we identify a third enzyme, termed "prodrug activation and resistance esterase" (PARE), that mediates low levels of LPC hydrolysis. Loss of PARE alone had no effect on the parasites ability to scavenge fatty acids from LPC. However, when combined with the loss of XL2 and XLH4, knockdown of PARE impacted the parasites ability to scavenge both choline and fatty acids from LPC. Furthermore, PARE/XL2/XLH4-deficient parasites were unable to complete a replication cycle when cultured in defined media with LPC as the sole source of exogenous fatty acids. We show that PARE is a membrane-associated enzyme with a substantial presence at the parasite periphery and propose a model whereby PARE catalyzes the hydrolysis of inwardly-diffusing LPC. Our findings reveal that asexual P. falciparum is dependent on parasite-encoded enzymes for LPC catabolism and rule out host erythrocyte enzymes as a physiologically-relevant source of lysophospholipase activity.

microbiology↗

bioRxiv2023

Metabolism of host lysophosphatidylcholine in Plasmodium falciparum-infected erythrocytes

The human malaria parasite Plasmodium falciparum requires exogenous fatty acids to support its growth during the pathogenic, asexual erythrocytic stage. Host serum lysophosphatidylcholine (LPC) is a significant fatty acid source, yet the metabolic processes responsible for the liberation of free fatty acids from exogenous LPC are unknown. Using a novel assay for LPC hydrolysis in P. falciparum-infected erythrocytes, we have identified small-molecule inhibitors of key in situ lysophospholipase activities. Competitive activity-based profiling and generation of a panel of single-to-quadruple knockout parasite lines revealed that two enzymes of the serine hydrolase superfamily, termed exported lipase (XL) 2 and exported lipase homolog (XLH) 4, are the dominant lysophospholipase activities in parasite-infected erythrocytes. The parasite ensures efficient exogenous LPC hydrolysis by directing these two enzymes to distinct locations: XL2 is exported to the erythrocyte, while XLH4 is retained within the parasite. While XL2 and XLH4 were individually dispensable with little effect on LPC hydrolysis in situ, loss of both enzymes resulted in a strong reduction in fatty acid scavenging from LPC, hyperproduction of phosphatidylcholine, and an enhanced sensitivity to LPC toxicity. Notably, growth of XL/XLH- deficient parasites was severely impaired when cultured in media containing LPC as the sole exogenous fatty acid source. Furthermore, when XL2 and XLH4 activities were ablated by genetic or pharmacologic means, parasites were unable to proliferate in human serum, a physiologically-relevant fatty acid source, revealing the essentiality of LPC hydrolysis in the host environment and its potential as a target for anti-malarial therapy.

microbiology↗

bioRxiv2019

Internalization of erythrocyte acylpeptide hydrolase is required for asexual replication of Plasmodium falciparum

The human malaria parasite Plasmodium falciparum causes disease as it replicates within the hosts erythrocytes. We have found that an erythrocyte serine hydrolase, acylpeptide hydrolase (APEH), accumulates within developing asexual parasites. Internalization of APEH was associated with a proteolytic event that reduced the size of the catalytic polypeptide from 80 to 55 kDa, which suggests that the enzyme resides in the food vacuole. A triazole urea APEH inhibitor, termed AA74-1, was employed to characterize the role of parasite-internalized APEH. In vitro, AA74-1 was a potent and highly selective inhibitor of both host erythrocyte and parasite-internalized APEH. When added to cultures of parasite-infected erythrocytes, AA74-1 was a relatively poor inhibitor of replication over one asexual replication cycle; however, its potency increased dramatically after a second cycle. This enhancement of potency was not abrogated by the addition of exogenous isopentenyl pyrophosphate, which distinguishes it from the well-characterized "delayed death" phenomenon that is observed with inhibitors that target the parasite apicoplast. Analysis of inhibition by AA74-1 in vivo revealed that a concentration of 100 nM was sufficient to quantitatively inhibit erythrocyte APEH. In contrast, the parasite-internalized APEH pool was inefficiently inhibited at concentrations up to 100-fold higher. Together, these findings provide evidence for an essential catalytic role for parasite-internalized APEH and suggest a model for AA74-1 growth inhibition whereby depletion of parasite APEH activity requires the internalization of inactive host cell APEH over two replication cycles. IMPORTANCENearly half a million deaths were attributed to malaria in 2017. Protozoan parasites of the genus Plasmodium cause disease in humans while replicating asexually within the hosts erythrocytes, with P. falciparum responsible for most of the mortality. Understanding how Plasmodium spp. has adapted to its unique host erythrocyte environment is important for developing malaria control strategies. Here, we demonstrate that P. falciparum co-opts a host erythrocyte serine hydrolase termed acylpeptide hydrolase. By showing that the parasite requires acylpeptide hydrolase activity for replication, we expand our knowledge of host cell factors that contribute to robust parasite growth.

microbiology↗