Perforin-like protein PPLP4 is crucial for mosquito midgut infection by Plasmodium falciparum

Pore forming proteins such as those belonging to the membrane attack/perforin (MACPF) family have important functions in many organisms. Of the five MACPF proteins found in Plasmodium parasites, three have functions in cell passage and one in host cell egress. Here we report an analysis of the perforin-like protein 4, PPLP4, in the rodent parasite Plasmodium berghei. We found that the protein is expressed only in the ookinete, the invasive stage of the parasite formed in the mosquito midgut. Transcriptional analysis revealed that expression of the pplp4 gene commences during ookinete development. The protein was detected in retorts and mature ookinetes. Using two antibodies, the protein was found localized in a dotted pattern, and 3-D SIM super-resolution microcopy revealed the protein in the periphery of the cell. Analysis of a C-terminal mCherry fusion of the protein however showed mainly cytoplasmic label. A pplp4 null mutant formed motile ookinetes, but these were unable to invade and traverse the midgut epithelium resulting in severely impaired oocyst formation and no transmission to naïve mice. However, when in vitro cultured ookinetes were injected into the thorax of the mosquito, thus by-passing midgut passage, sporozoites were formed and the mutant parasites were able to infect naïve mice. Taken together, our data show that PPLP4 is required only for ookinete invasion of the mosquito midgut. Thus PPLP4 has a similar role to the previously studied PPLP3 and PPLP5, raising the question why three proteins with MACPF domains are needed for invasion by the ookinete of the mosquito midgut epithelium.

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“…berghei and P . falciparum [ 14 , 15 ]. In both cases, mutant parasites lacking the protein were unable to invade the midgut epithelium.…”

Section: Introductionmentioning

confidence: 99%

Essential role of Plasmodium perforin-like protein 4 in ookinete midgut passage

et al. 2018

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“…7-Helix-1-KO: 7-Helix-1-KO parasites were generated via single cross-over homologous recombination using the pCAM-BSD vector [85–88]. A 534-bp gene fragment homologous to a region of the N-terminus of the gene was amplified via PCR using the respective 7-Helix-1-KO primers (for primer sequences, see S2 Table).…”

Section: Methodsmentioning

confidence: 99%

A seven-helix protein constitutes stress granules crucial for regulating translation during human-to-mosquito transmission of Plasmodium falciparum

et al. 2018

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The complex life-cycle of the human malaria parasite Plasmodium falciparum requires a high degree of tight coordination allowing the parasite to adapt to changing environments. One of the major challenges for the parasite is the human-to-mosquito transmission, which starts with the differentiation of blood stage parasites into the transmissible gametocytes, followed by the rapid conversion of the gametocytes into gametes, once they are taken up by the blood-feeding Anopheles vector. In order to pre-adapt to this change of host, the gametocytes store transcripts in stress granules that encode proteins needed for parasite development in the mosquito. Here we report on a novel stress granule component, the seven-helix protein 7-Helix-1. The protein, a homolog of the human stress response regulator LanC-like 2, accumulates in stress granules of female gametocytes and interacts with ribonucleoproteins, such as CITH, DOZI, and PABP1. Malaria parasites lacking 7-Helix-1 are significantly impaired in female gametogenesis and thus transmission to the mosquito. Lack of 7-Helix-1 further leads to a deregulation of components required for protein synthesis. Consistently, inhibitors of translation could mimic the 7-Helix-1 loss-of-function phenotype. 7-Helix-1 forms a complex with the RNA-binding protein Puf2, a translational regulator of the female-specific antigen Pfs25, as well as with pfs25-coding mRNA. In accord, gametocytes deficient of 7-Helix-1 exhibit impaired Pfs25 synthesis. Our data demonstrate that 7-Helix-1 constitutes stress granules crucial for regulating the synthesis of proteins needed for life-cycle progression of Plasmodium in the mosquito vector.

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“…Other microneme proteins assigned to midgut traversal of P . berghei ookinetes include SOAP, WARP and CelTOS (cell‐traversal protein for ookinetes and sporozoites) (Yuda et al ., 2001; Dessens et al ., 2003; Kadota et al ., 2004; Li et al ., 2004; Kariu et al ., 2006; Ecker et al ., 2007, 2008; Kaneko et al ., 2015; Wirth et al ., 2015) (Table 1). …”

Section: The Zygote‐to‐ookinete Conversionmentioning

confidence: 99%

The development of malaria parasites in the mosquito midgut

Bennink

Kiesow

Pradel

2016

Cellular Microbiology

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163

155

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SummaryThe mosquito midgut stages of malaria parasites are crucial for establishing an infection in the insect vector and to thus ensure further spread of the pathogen. Parasite development in the midgut starts with the activation of the intraerythrocytic gametocytes immediately after take‐up and ends with traversal of the midgut epithelium by the invasive ookinetes less than 24 h later. During this time period, the plasmodia undergo two processes of stage conversion, from gametocytes to gametes and from zygotes to ookinetes, both accompanied by dramatic morphological changes. Further, gamete formation requires parasite egress from the enveloping erythrocytes, rendering them vulnerable to the aggressive factors of the insect gut, like components of the human blood meal. The mosquito midgut stages of malaria parasites are unprecedented objects to study a variety of cell biological aspects, including signal perception, cell conversion, parasite/host co‐adaptation and immune evasion. This review highlights recent insights into the molecules involved in gametocyte activation and gamete formation as well as in zygote‐to‐ookinete conversion and ookinete midgut exit; it further discusses factors that can harm the extracellular midgut stages as well as the measures of the parasites to protect themselves from any damage.

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Perforin-like protein PPLP4 is crucial for mosquito midgut infection by Plasmodium falciparum

Cited by 24 publications

References 38 publications

Essential role of Plasmodium perforin-like protein 4 in ookinete midgut passage

Essential role of Plasmodium perforin-like protein 4 in ookinete midgut passage

A seven-helix protein constitutes stress granules crucial for regulating translation during human-to-mosquito transmission of Plasmodium falciparum

The development of malaria parasites in the mosquito midgut

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