PEXEL is a proteolytic maturation site for both exported and non-exported
            <i>Plasmodium</i>
            proteins

Fierro, Manuel A.; Muheljic, Ajla; Sha, Jihui; Wohlschlegel, James; Beck, Josh R.

doi:10.1128/msphere.00393-23

Cited by 2 publications

(2 citation statements)

References 64 publications

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“…First, UIS2 is a membrane protein located at the parasitophorous vacuole membrane (PVM), a barrier between the parasite and the host cell cytoplasm, during the blood stages of P. falciparum (13). As the membrane-targeting motif lies within UIS2-NTD (36), UIS2-NTD likely recruits P-eIF2alpha to the PVM for dephosphorylation. Second, P-eIF2alpha typically forms a nonproductive complex with eIF2B, where the phosphorylated Serine-containing loop binds to the cavity between eIF2Balpha and eIF2Bdelta, inhibiting the eIF2B complex’s ability to exchange GTP (37-39).…”

Section: Discussionmentioning

confidence: 99%

Structural and mechanistic insights intoPlasmodiumeIF2alpha dephosphorylation by UIS2 during the erythrocytic stage

Wu,

Wagner

2024

Preprint

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UIS2 is a promising therapeutic target for malaria due to its essential role in the transmission and infectivity ofPlasmodiumto the host hepatocytes. InPlasmodium, UIS2 acts as a phosphatase toward phosphorylated eIF2alpha at Ser59, regulating translation initiation. However, its role during the erythrocytic stage, which causes clinical symptoms, remains unclear, and its protein structure for elucidating the dephosphorylation mechanism is unavailable. In this study, we analyzed thePlasmodiumphenotype screening database and found thatUIS2-deficientPlasmodiumfails to proliferate during the erythrocytic stages. Single-cell transcriptomic data from the Malaria Cell Atlas revealedUIS2expression during both hepatic and erythrocytic stages, with significant upregulation in trophozoites and late schizonts, suggesting UIS2’s essential role in erythrocytic stage development. Structural analyses using AlphaFold modeling demonstrated that the UIS2 phosphatase domain (UIS2-PD) shares homology with human purple acid phosphatase, featuring conserved catalytic site residues. We observed that the N-terminal domain of UIS2 interacts with the S1 domain loop of a phospho-mimic mutant (Ser59Asp) eIF2alpha via electrostatic interactions. This protein interaction is distal to the phosphatase domain, indicating a unique substrate recruitment mechanism distinct from mammalian serine/threonine phosphatase PP1. Additionally, we identified a negatively charged cavity in UIS2-PD capable of binding the Ser59-containing loop in eIF2alpha for substrate recognition. Molecular docking studies showed that the phosphatase inhibitor salubrinal binds to this negatively charged cavity, potentially obstructing enzyme-substrate interactions. These structural insights into UIS2 and its interaction with eIF2alpha provide promising avenues for developing novel antimalarial drugs.Significance StatementMalaria poses a significant global health challenge, particularly with rising resistance to artemisinin therapies. This study reveals the critical role of UIS2 inPlasmodiumproliferation during the symptomatic blood stage through phenotype screening and single-cell transcriptomics. We characterized the catalytic site within UIS2-PD and discovered a surface cavity for recognizing phosphorylated eIF2alpha by UIS2-PD, which can be inhibited by small molecules. Our findings identify UIS2 as a promising target for new antimalarial drugs, addressing both blood-stage parasites to alleviate clinical symptoms and liver-stage parasites for prophylactic treatment. This dual targeting strategy could prevent malaria onset post-exposure and reduce the overall parasite burden. The protein interaction between UIS2 and eIF2alpha is chemically targetable, facilitating the development of effective UIS2 inhibitors.

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Section: Discussionmentioning

confidence: 99%

Structural and mechanistic insights intoPlasmodiumeIF2alpha dephosphorylation by UIS2 during the erythrocytic stage

Wu,

Wagner

2024

Preprint

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“…Interestingly, numerous PEXEL proteins localize at the PV/PVM rather than the host cell ( 35 , 39 – 42 ). Several recently characterized P. falciparum PEXEL proteins also localize at the PV/PVM ( 43 – 45 ). While this peripheral localization could be interpreted as non-exported, it is possible that the protein binds to the cytoplasmic face of the PVM via a peripheral protein-protein interaction following export and so biochemical assessment of membrane binding and topology is needed in order to be conclusive.…”

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confidence: 99%

Flp/ FRT -mediated disruption of ptex150 and exp2 in Plasmodium falciparum sporozoites inhibits liver-stage development

McConville,

Krol,

Steel

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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Plasmodium falciparum causes severe malaria and assembles a protein translocon (PTEX) complex at the parasitophorous vacuole membrane (PVM) of infected erythrocytes, through which several hundred proteins are exported to facilitate growth. The preceding liver stage of infection involves growth in a hepatocyte-derived PVM; however, the importance of protein export during P. falciparum liver infection remains unexplored. Here, we use the FlpL/ FRT system to conditionally excise genes in P. falciparum sporozoites for functional liver-stage studies. Disruption of PTEX members ptex150 and exp2 did not affect sporozoite development in mosquitoes or infectivity for hepatocytes but attenuated liver-stage growth in humanized mice. While PTEX150 deficiency reduced fitness on day 6 postinfection by 40%, EXP2 deficiency caused 100% loss of liver parasites, demonstrating that PTEX components are required for growth in hepatocytes to differing degrees. To characterize PTEX loss-of-function mutations, we localized four liver-stage Plasmodium export element (PEXEL) proteins. P. falciparum liver specific protein 2 (LISP2), liver-stage antigen 3 (LSA3), circumsporozoite protein (CSP), and a Plasmodium berghei LISP2 reporter all localized to the periphery of P. falciparum liver stages but were not exported beyond the PVM. Expression of LISP2 and CSP but not LSA3 was reduced in ptex150-FRT and exp2-FRT liver stages, suggesting that expression of some PEXEL proteins is affected directly or indirectly by PTEX disruption. These results show that PTEX150 and EXP2 are important for P. falciparum development in hepatocytes and emphasize the emerging complexity of PEXEL protein trafficking.

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PEXEL is a proteolytic maturation site for both exported and non-exported Plasmodium proteins

Cited by 2 publications

References 64 publications

Structural and mechanistic insights intoPlasmodiumeIF2alpha dephosphorylation by UIS2 during the erythrocytic stage

Structural and mechanistic insights intoPlasmodiumeIF2alpha dephosphorylation by UIS2 during the erythrocytic stage

Flp/ FRT -mediated disruption of ptex150 and exp2 in Plasmodium falciparum sporozoites inhibits liver-stage development

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