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The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly

Plasmodium falciparum mediates adhesion of infected red blood cells (RBCs) to blood vessel walls by assembling a multi-protein complex at the RBC surface. This virulence-mediating structure, called the knob, acts as a scaffold for the presentation of the major virulence antigen, P. falciparum Erythr...

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Autores principales: Looker, Oliver, Blanch, Adam J., Liu, Boyin, Nunez-Iglesias, Juan, McMillan, Paul J., Tilley, Leann, Dixon, Matthew W. A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6529015/
https://www.ncbi.nlm.nih.gov/pubmed/31071194
http://dx.doi.org/10.1371/journal.ppat.1007761
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author Looker, Oliver
Blanch, Adam J.
Liu, Boyin
Nunez-Iglesias, Juan
McMillan, Paul J.
Tilley, Leann
Dixon, Matthew W. A.
author_facet Looker, Oliver
Blanch, Adam J.
Liu, Boyin
Nunez-Iglesias, Juan
McMillan, Paul J.
Tilley, Leann
Dixon, Matthew W. A.
author_sort Looker, Oliver
collection PubMed
description Plasmodium falciparum mediates adhesion of infected red blood cells (RBCs) to blood vessel walls by assembling a multi-protein complex at the RBC surface. This virulence-mediating structure, called the knob, acts as a scaffold for the presentation of the major virulence antigen, P. falciparum Erythrocyte Membrane Protein-1 (PfEMP1). In this work we developed correlative STochastic Optical Reconstruction Microscopy–Scanning Electron Microscopy (STORM-SEM) to spatially and temporally map the delivery of the knob-associated histidine-rich protein (KAHRP) and PfEMP1 to the RBC membrane skeleton. We show that KAHRP is delivered as individual modules that assemble in situ, giving a ring-shaped fluorescence profile around a dimpled disk that can be visualized by SEM. Electron tomography of negatively-stained membranes reveals a previously observed spiral scaffold underpinning the assembled knobs. Truncation of the C-terminal region of KAHRP leads to loss of the ring structures, disruption of the raised disks and aberrant formation of the spiral scaffold, pointing to a critical role for KAHRP in assembling the physical knob structure. We show that host cell actin remodeling plays an important role in assembly of the virulence complex, with cytochalasin D blocking knob assembly. Additionally, PfEMP1 appears to be delivered to the RBC membrane, then inserted laterally into knob structures.
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spelling pubmed-65290152019-05-31 The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly Looker, Oliver Blanch, Adam J. Liu, Boyin Nunez-Iglesias, Juan McMillan, Paul J. Tilley, Leann Dixon, Matthew W. A. PLoS Pathog Research Article Plasmodium falciparum mediates adhesion of infected red blood cells (RBCs) to blood vessel walls by assembling a multi-protein complex at the RBC surface. This virulence-mediating structure, called the knob, acts as a scaffold for the presentation of the major virulence antigen, P. falciparum Erythrocyte Membrane Protein-1 (PfEMP1). In this work we developed correlative STochastic Optical Reconstruction Microscopy–Scanning Electron Microscopy (STORM-SEM) to spatially and temporally map the delivery of the knob-associated histidine-rich protein (KAHRP) and PfEMP1 to the RBC membrane skeleton. We show that KAHRP is delivered as individual modules that assemble in situ, giving a ring-shaped fluorescence profile around a dimpled disk that can be visualized by SEM. Electron tomography of negatively-stained membranes reveals a previously observed spiral scaffold underpinning the assembled knobs. Truncation of the C-terminal region of KAHRP leads to loss of the ring structures, disruption of the raised disks and aberrant formation of the spiral scaffold, pointing to a critical role for KAHRP in assembling the physical knob structure. We show that host cell actin remodeling plays an important role in assembly of the virulence complex, with cytochalasin D blocking knob assembly. Additionally, PfEMP1 appears to be delivered to the RBC membrane, then inserted laterally into knob structures. Public Library of Science 2019-05-09 /pmc/articles/PMC6529015/ /pubmed/31071194 http://dx.doi.org/10.1371/journal.ppat.1007761 Text en © 2019 Looker et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Looker, Oliver
Blanch, Adam J.
Liu, Boyin
Nunez-Iglesias, Juan
McMillan, Paul J.
Tilley, Leann
Dixon, Matthew W. A.
The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title_full The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title_fullStr The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title_full_unstemmed The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title_short The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly
title_sort knob protein kahrp assembles into a ring-shaped structure that underpins virulence complex assembly
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6529015/
https://www.ncbi.nlm.nih.gov/pubmed/31071194
http://dx.doi.org/10.1371/journal.ppat.1007761
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