Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.

Asparagine synthetase (AS) catalyzes the ATP-dependent conversion of aspartate into asparagine using ammonia or glutamine as nitrogen source. There are two distinct types of AS, asparagine synthetase A (AS-A), known as strictly ammonia-dependent, and asparagine synthetase B (AS-B), which can use eit...

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Autores principales:	Inês Loureiro, Joana Faria, Christine Clayton, Sandra Macedo Ribeiro, Nilanjan Roy, Nuno Santarém, Joana Tavares, Anabela Cordeiro-da-Silva
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270
Acceso en línea:	https://doaj.org/article/c0ab720a2516465d9ac83aeaad32d3fa
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spelling	oai:doaj.org-article:c0ab720a2516465d9ac83aeaad32d3fa2021-11-18T09:16:37ZKnockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.1935-27271935-273510.1371/journal.pntd.0002578https://doaj.org/article/c0ab720a2516465d9ac83aeaad32d3fa2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24340117/?tool=EBIhttps://doaj.org/toc/1935-2727https://doaj.org/toc/1935-2735Asparagine synthetase (AS) catalyzes the ATP-dependent conversion of aspartate into asparagine using ammonia or glutamine as nitrogen source. There are two distinct types of AS, asparagine synthetase A (AS-A), known as strictly ammonia-dependent, and asparagine synthetase B (AS-B), which can use either ammonia or glutamine. The absence of AS-A in humans, and its presence in trypanosomes, suggested AS-A as a potential drug target that deserved further investigation. We report the presence of functional AS-A in Trypanosoma cruzi (TcAS-A) and Trypanosoma brucei (TbAS-A): the purified enzymes convert L-aspartate into L-asparagine in the presence of ATP, ammonia and Mg(2+). TcAS-A and TbAS-A use preferentially ammonia as a nitrogen donor, but surprisingly, can also use glutamine, a characteristic so far never described for any AS-A. TbAS-A knockdown by RNAi didn't affect in vitro growth of bloodstream forms of the parasite. However, growth was significantly impaired when TbAS-A knockdown parasites were cultured in medium with reduced levels of asparagine. As expected, mice infections with induced and non-induced T. brucei RNAi clones were similar to those from wild-type parasites. However, when induced T. brucei RNAi clones were injected in mice undergoing asparaginase treatment, which depletes blood asparagine, the mice exhibited lower parasitemia and a prolonged survival in comparison to similarly-treated mice infected with control parasites. Our results show that TbAS-A can be important under in vivo conditions when asparagine is limiting, but is unlikely to be suitable as a drug target.Inês LoureiroJoana FariaChristine ClaytonSandra Macedo RibeiroNilanjan RoyNilanjan RoyNuno SantarémJoana TavaresAnabela Cordeiro-da-SilvaPublic Library of Science (PLoS)articleArctic medicine. Tropical medicineRC955-962Public aspects of medicineRA1-1270ENPLoS Neglected Tropical Diseases, Vol 7, Iss 12, p e2578 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270
spellingShingle	Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Inês Loureiro Joana Faria Christine Clayton Sandra Macedo Ribeiro Nilanjan Roy Nilanjan Roy Nuno Santarém Joana Tavares Anabela Cordeiro-da-Silva Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
description	Asparagine synthetase (AS) catalyzes the ATP-dependent conversion of aspartate into asparagine using ammonia or glutamine as nitrogen source. There are two distinct types of AS, asparagine synthetase A (AS-A), known as strictly ammonia-dependent, and asparagine synthetase B (AS-B), which can use either ammonia or glutamine. The absence of AS-A in humans, and its presence in trypanosomes, suggested AS-A as a potential drug target that deserved further investigation. We report the presence of functional AS-A in Trypanosoma cruzi (TcAS-A) and Trypanosoma brucei (TbAS-A): the purified enzymes convert L-aspartate into L-asparagine in the presence of ATP, ammonia and Mg(2+). TcAS-A and TbAS-A use preferentially ammonia as a nitrogen donor, but surprisingly, can also use glutamine, a characteristic so far never described for any AS-A. TbAS-A knockdown by RNAi didn't affect in vitro growth of bloodstream forms of the parasite. However, growth was significantly impaired when TbAS-A knockdown parasites were cultured in medium with reduced levels of asparagine. As expected, mice infections with induced and non-induced T. brucei RNAi clones were similar to those from wild-type parasites. However, when induced T. brucei RNAi clones were injected in mice undergoing asparaginase treatment, which depletes blood asparagine, the mice exhibited lower parasitemia and a prolonged survival in comparison to similarly-treated mice infected with control parasites. Our results show that TbAS-A can be important under in vivo conditions when asparagine is limiting, but is unlikely to be suitable as a drug target.
format	article
author	Inês Loureiro Joana Faria Christine Clayton Sandra Macedo Ribeiro Nilanjan Roy Nilanjan Roy Nuno Santarém Joana Tavares Anabela Cordeiro-da-Silva
author_facet	Inês Loureiro Joana Faria Christine Clayton Sandra Macedo Ribeiro Nilanjan Roy Nilanjan Roy Nuno Santarém Joana Tavares Anabela Cordeiro-da-Silva
author_sort	Inês Loureiro
title	Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
title_short	Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
title_full	Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
title_fullStr	Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
title_full_unstemmed	Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.
title_sort	knockdown of asparagine synthetase a renders trypanosoma brucei auxotrophic to asparagine.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/c0ab720a2516465d9ac83aeaad32d3fa
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Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine.

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