Malaria parasite translocon structure and mechanism of effector export

Ho, Chi-Min; Beck, Josh R.; Lai, Mason; Cui, Yanxiang; Goldberg, Daniel E.; Egea, Pascal F.; Zhou, Hong

doi:10.1107/s0108767320099675

Cited by 15 publications

(39 citation statements)

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“…Considering the wide distribution of the conductance, it may possible that the EXP2 formed polydisperse-sized nanopores assembled from 5 to 9 monomers, with the 7-mer nanopore most frequently observed. This result was consistent with the in vivo condition that the EXP2 nanopore is combined with other translocon components [38].…”

Section: Analysis Of the Pore Size And The Number Of Assembled Exp2 M...supporting

confidence: 90%

“…Although cryo‐electron microscopy observations showed the rigid structure of EXP2 as a part of the translocon [38], it is necessary to investigate the dynamic pore size of EXP2 in the lipid bilayer without the other translocon components. The size of the pore can be theoretically calculated using the current conductance of the step signals and Hille's equation as follows:

\begin{equation}R\; = \left( {l + \frac{{\pi r}}{2}} \right)\;\frac{\rho }{{\pi {r^2}}}\end{equation}

…”

Section: Resultsmentioning

confidence: 99%

“…We have focused on EXP2 as the peptide‐detectable nanopore because a translocon can transport a protein chain with unthreaded through the pore. The translocon called PTEX supports the malaria parasites to proliferate in human red blood cells by exporting proteins [38]. PTEX is composed of five proteins; EXP2 constitutes the transmembrane pore (Figure S1), while the other components play a role in unfolding the luggage proteins.…”

Section: Introductionmentioning

confidence: 99%

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Single polypeptide detection using a translocon EXP2 nanopore

et al. 2021

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DNA sequencing using nanopores has already been achieved and commercialized; the next step in advancing nanopore technology is towards protein sequencing. Although trials have been reported for discriminating the 20 amino acids using biological nanopores and short peptide carriers, it remains challenging. The size compatibility between nanopores and peptides is one of the issues to be addressed. Therefore, exploring biological nanopores that are suitable for peptide sensing is key in achieving amino acid sequence determination. Here, we focus on EXP2, the transmembrane protein of a translocon from malaria parasites, and describe its pore‐forming properties in the lipid bilayer. EXP2 mainly formed a nanopore with a diameter of 2.5 nm assembled from 7 monomers. Using the EXP2 nanopore allowed us to detect poly‐L‐lysine (PLL) at a single‐molecule level. Furthermore, the EXP2 nanopore has sufficient resolution to distinguish the difference in molecular weight between two individual PLL, long PLL (Mw: 30,000–70,000) and short PLL (Mw: 10,000). Our results contribute to the accumulation of information for peptide‐detectable nanopores.

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Section: Analysis Of the Pore Size And The Number Of Assembled Exp2 M...supporting

confidence: 90%

\begin{equation}R\; = \left( {l + \frac{{\pi r}}{2}} \right)\;\frac{\rho }{{\pi {r^2}}}\end{equation}

…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Single polypeptide detection using a translocon EXP2 nanopore

et al. 2021

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“…From a technical perspective, the current work demonstrates an approach for direct visualization, at near-atomic resolution, of native protein complexes as they exist on membranes or in the cellular milieu. As such, notwithstanding obvious challenges in dealing with species only existing transiently in cells, this approach opens the door for structural study of native macromolecular complexes to capture their multiple conformational states ( e.g., changes in binding partners 53 or cycling through sub-complexes like the spliceosome 54,55 ) and during various functional stages ( e.g. , genesis of RBC in health and progression of pathology in diseases 56 ).…”

Section: Discussionmentioning

confidence: 99%

Structure, dynamics and assembly of the ankyrin complex on human red blood cell membrane

Xia

Liu

2022

Preprint

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The cytoskeleton of red blood cell (RBC) is anchored to cell membrane by the ankyrin complex. This complex is assembled during RBC genesis and comprises primarily band 3, protein 4.2 and ankyrin, whose mutations contribute to numerous human inherited diseases. High-resolution structures of the ankyrin complex have been long sought-after to understand its assembly and disease-causing mutations. Here, we analyzed native complexes on human RBC membrane by stepwise fractionation. Cryo-electron microscopy structures of nine band 3-associated complexes reveal that protein 4.2 stabilizes the cytoplasmic domain of band 3 dimer. In turn, the superhelix-shaped ankyrin binds to this protein 4.2 via ankyrin repeats (ARs) 6-13 and to another band 3 dimer via ARs 17-20, bridging two band 3 dimers in the ankyrin complex. Integration of these structures with both prior and our biochemical data supports a model of ankyrin complex assembly during erythropoiesis and identifies interactions essential for mechanical stability of RBC.

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“…Anthrax toxin inflicts harm on the host only after translocation across host cell membranes. Protein translocation consists of two steps: recruitment of a cytotoxic enzyme to the cell surface accompanied by partial unfolding and threading of the enzyme through the narrow conduit of a translocon, which spans the host cell membrane (Ho et al, 2018;Krantz et al, 2006;Matouschek, 2003;Wickner and Schekman, 2005;Zhang et al, 2004). Specific to anthrax, two enzyme factors, edema factor (EF, 89 kDa) and lethal factor (LF, 91 kDa), are translocated by the membrane protein protective antigen (PA, 83 kDa).…”

Section: Introductionmentioning

confidence: 99%