TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis

ABSTRACT In the protozoan parasite Toxoplasma gondii, protein kinases have been shown to play key roles in regulating parasite motility, invasion, replication, egress, and survival within the host. The tyrosine kinase-like (TKL) family of proteins are an unexplored set of kinases in Toxoplasma. Of t...

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Autores principales: Joseph M. Varberg, Isabelle Coppens, Gustavo Arrizabalaga, Rajshekhar Y. Gaji
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Publicado: American Society for Microbiology 2018
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spelling oai:doaj.org-article:eb07f9187fe0497192722b5ff1dc6c172021-11-15T15:53:26ZTgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis10.1128/mBio.00301-182150-7511https://doaj.org/article/eb07f9187fe0497192722b5ff1dc6c172018-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00301-18https://doaj.org/toc/2150-7511ABSTRACT In the protozoan parasite Toxoplasma gondii, protein kinases have been shown to play key roles in regulating parasite motility, invasion, replication, egress, and survival within the host. The tyrosine kinase-like (TKL) family of proteins are an unexplored set of kinases in Toxoplasma. Of the eight annotated TKLs in the Toxoplasma genome, a recent genome-wide loss-of-function screen showed that six are important for tachyzoite fitness. By utilizing an endogenous tagging approach, we showed that these six T. gondii TKLs (TgTKLs) localize to various subcellular compartments, including the nucleus, the cytosol, the inner membrane complex, and the Golgi apparatus. To gain insight into the function of TKLs in Toxoplasma, we first characterized TgTKL1, which contains the plant-like enhanced disease resistance 1 (EDR1) domain and localizes to the nucleus. TgTKL1 knockout parasites displayed significant defects in progression through the lytic cycle; we show that the defects were due to specific impairment of host cell attachment. Transcriptomics analysis identified over 200 genes of diverse functions that were differentially expressed in TgTKL1 knockout parasites. Importantly, numerous genes implicated in host cell attachment and invasion were among those most significantly downregulated, resulting in defects in microneme secretion and processing. Significantly, all of the mice inoculated intraperitoneally with TgTKL1 knockout parasites survived the infection, suggesting that TgTKL1 plays an essential role in acute toxoplasmosis. Together, these findings suggest that TgTKL1 mediates a signaling pathway that regulates the expression of multiple factors required for parasite virulence, underscoring the potential of this kinase as a novel therapeutic target. IMPORTANCE Toxoplasma gondii is a protozoan parasite that can cause chronic and life-threatening disease in mammals; new drugs are greatly needed for treatment. One attractive group of drug targets consists of parasite kinases containing unique features that distinguish them from host proteins. In this report, we identify and characterize a previously unstudied kinase, TgTKL1, that localizes to the nucleus and contains a domain architecture unique to plants and protozoa. By disrupting TgTKL1, we showed that this kinase is required for the proper expression of hundreds of genes, including many that are required for the parasite to gain entry into the host cell. Specifically, parasites lacking TgTKL1 have defects in host cell attachment, resulting in impaired growth in vitro and a complete loss of virulence in mice. This report provides insight into the importance of the parasite tyrosine kinase-like kinases and establishes TgTKL1 as a novel and essential virulence factor in Toxoplasma.Joseph M. VarbergIsabelle CoppensGustavo ArrizabalagaRajshekhar Y. GajiAmerican Society for Microbiologyarticleapicomplexan parasiteskinaseToxoplasma gondiihost cell invasionMicrobiologyQR1-502ENmBio, Vol 9, Iss 2 (2018)
institution DOAJ
collection DOAJ
language EN
topic apicomplexan parasites
kinase
Toxoplasma gondii
host cell invasion
Microbiology
QR1-502
spellingShingle apicomplexan parasites
kinase
Toxoplasma gondii
host cell invasion
Microbiology
QR1-502
Joseph M. Varberg
Isabelle Coppens
Gustavo Arrizabalaga
Rajshekhar Y. Gaji
TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
description ABSTRACT In the protozoan parasite Toxoplasma gondii, protein kinases have been shown to play key roles in regulating parasite motility, invasion, replication, egress, and survival within the host. The tyrosine kinase-like (TKL) family of proteins are an unexplored set of kinases in Toxoplasma. Of the eight annotated TKLs in the Toxoplasma genome, a recent genome-wide loss-of-function screen showed that six are important for tachyzoite fitness. By utilizing an endogenous tagging approach, we showed that these six T. gondii TKLs (TgTKLs) localize to various subcellular compartments, including the nucleus, the cytosol, the inner membrane complex, and the Golgi apparatus. To gain insight into the function of TKLs in Toxoplasma, we first characterized TgTKL1, which contains the plant-like enhanced disease resistance 1 (EDR1) domain and localizes to the nucleus. TgTKL1 knockout parasites displayed significant defects in progression through the lytic cycle; we show that the defects were due to specific impairment of host cell attachment. Transcriptomics analysis identified over 200 genes of diverse functions that were differentially expressed in TgTKL1 knockout parasites. Importantly, numerous genes implicated in host cell attachment and invasion were among those most significantly downregulated, resulting in defects in microneme secretion and processing. Significantly, all of the mice inoculated intraperitoneally with TgTKL1 knockout parasites survived the infection, suggesting that TgTKL1 plays an essential role in acute toxoplasmosis. Together, these findings suggest that TgTKL1 mediates a signaling pathway that regulates the expression of multiple factors required for parasite virulence, underscoring the potential of this kinase as a novel therapeutic target. IMPORTANCE Toxoplasma gondii is a protozoan parasite that can cause chronic and life-threatening disease in mammals; new drugs are greatly needed for treatment. One attractive group of drug targets consists of parasite kinases containing unique features that distinguish them from host proteins. In this report, we identify and characterize a previously unstudied kinase, TgTKL1, that localizes to the nucleus and contains a domain architecture unique to plants and protozoa. By disrupting TgTKL1, we showed that this kinase is required for the proper expression of hundreds of genes, including many that are required for the parasite to gain entry into the host cell. Specifically, parasites lacking TgTKL1 have defects in host cell attachment, resulting in impaired growth in vitro and a complete loss of virulence in mice. This report provides insight into the importance of the parasite tyrosine kinase-like kinases and establishes TgTKL1 as a novel and essential virulence factor in Toxoplasma.
format article
author Joseph M. Varberg
Isabelle Coppens
Gustavo Arrizabalaga
Rajshekhar Y. Gaji
author_facet Joseph M. Varberg
Isabelle Coppens
Gustavo Arrizabalaga
Rajshekhar Y. Gaji
author_sort Joseph M. Varberg
title TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
title_short TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
title_full TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
title_fullStr TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
title_full_unstemmed TgTKL1 Is a Unique Plant-Like Nuclear Kinase That Plays an Essential Role in Acute Toxoplasmosis
title_sort tgtkl1 is a unique plant-like nuclear kinase that plays an essential role in acute toxoplasmosis
publisher American Society for Microbiology
publishDate 2018
url https://doaj.org/article/eb07f9187fe0497192722b5ff1dc6c17
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