Differential requirements for cyclase-associated protein (CAP) in actin-dependent processes of Toxoplasma gondii
- The Francis Crick Institute, United Kingdom
- University of Vermont, United States
- University of Connecticut, United States
Abstract
Toxoplasma gondii contains a limited subset of actin binding proteins. Here we show that the putative actin regulator cyclase-associated protein (CAP) is present in two different isoforms and its deletion leads to significant defects in some but not all actin dependent processes. We observe defects in cell-cell communication, daughter cell orientation and the juxtanuclear accumulation of actin, but only modest defects in synchronicity of division and no defect in the replication of the apicoplast. 3D electron microscopy reveals that loss of CAP results in a defect in formation of a normal central residual body, but parasites remain connected within the vacuole. This dissociates synchronicity of division and parasite rosetting and reveals that establishment and maintenance of the residual body may be more complex than previously thought. These results highlight the different spatial requirements for F-actin regulation in Toxoplasma which appear to be achieved by partially overlapping functions of actin regulators.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 4, 5, 6, 8 and 10. Data Availability: Raw data for FIB SEM supporting movies will be uploaded to EMPIAR. Raw data for FIB SEM supporting movies have been deposited to EMPIAR.
Article and author information
Author details
Matthew Robert Geoffrey Russell
Funding
Francis Crick Institute (FC001189)
- Lucy Collinson
NIH Office of the Director (AI121885)
- Romain Carmeille
- Aoife Heaslip
NIH Office of the Director (AI139201)
- Robyn Kent
- Gary E Ward
Francis Crick Institute (FC001999)
- Matthew Robert Geoffrey Russell
- Christopher J Peddie
- Lucy Collinson
NIH Office of the Director (AI137767)
- Robyn Kent
- Gary E Ward
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All experiments were performed in accordance with UK Home Office regulations (PPL 80/2616) and approved by the ethical review panel at the Francis Crick Institute.
Copyright
© 2019, Hunt et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,212
- views
-
- 308
- downloads
-
- 53
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Differential requirements for cyclase-associated protein (CAP) in actin-dependent processes of Toxoplasma gondii
eLife 8:e50598.
https://doi.org/10.7554/eLife.50598
Further reading
-
- Microbiology and Infectious Disease
The persistence of latent viral reservoirs remains the major obstacle to eradicating human immunodeficiency virus (HIV). We herein found that ICP34.5 can act as an antagonistic factor for the reactivation of HIV latency by herpes simplex virus type I (HSV-1), and thus recombinant HSV-1 with ICP34.5 deletion could more effectively reactivate HIV latency than its wild-type counterpart. Mechanistically, HSV-ΔICP34.5 promoted the phosphorylation of HSF1 by decreasing the recruitment of protein phosphatase 1 (PP1α), thus effectively binding to the HIV LTR to reactivate the latent reservoirs. In addition, HSV-ΔICP34.5 enhanced the phosphorylation of IKKα/β through the degradation of IκBα, leading to p65 accumulation in the nucleus to elicit NF-κB pathway-dependent reactivation of HIV latency. Then, we constructed the recombinant HSV-ΔICP34.5 expressing simian immunodeficiency virus (SIV) env, gag, or the fusion antigen sPD1-SIVgag as a therapeutic vaccine, aiming to achieve a functional cure by simultaneously reactivating viral latency and eliciting antigen-specific immune responses. Results showed that these constructs effectively elicited SIV-specific immune responses, reactivated SIV latency, and delayed viral rebound after the interruption of antiretroviral therapy (ART) in chronically SIV-infected rhesus macaques. Collectively, these findings provide insights into the rational design of HSV-vectored therapeutic strategies for pursuing an HIV functional cure.
-
- Biochemistry and Chemical Biology
- Microbiology and Infectious Disease
Teichoic acids (TA) are linear phospho-saccharidic polymers and important constituents of the cell envelope of Gram-positive bacteria, either bound to the peptidoglycan as wall teichoic acids (WTA) or to the membrane as lipoteichoic acids (LTA). The composition of TA varies greatly but the presence of both WTA and LTA is highly conserved, hinting at an underlying fundamental function that is distinct from their specific roles in diverse organisms. We report the observation of a periplasmic space in Streptococcus pneumoniae by cryo-electron microscopy of vitreous sections. The thickness and appearance of this region change upon deletion of genes involved in the attachment of TA, supporting their role in the maintenance of a periplasmic space in Gram-positive bacteria as a possible universal function. Consequences of these mutations were further examined by super-resolved microscopy, following metabolic labeling and fluorophore coupling by click chemistry. This novel labeling method also enabled in-gel analysis of cell fractions. With this approach, we were able to titrate the actual amount of TA per cell and to determine the ratio of WTA to LTA. In addition, we followed the change of TA length during growth phases, and discovered that a mutant devoid of LTA accumulates the membrane-bound polymerized TA precursor.
