title: Leishmania infantum Asparagine Synthetase A Is Dispensable for Parasites Survival and Infectivity.
abstract: A growing interest in asparagine (Asn) metabolism has currently been observed in cancer and infection fields. Asparagine synthetase (AS) is responsible for the conversion of aspartate into Asn in an ATP-dependent manner, using ammonia or glutamine as a nitrogen source. There are two structurally distinct AS: the strictly ammonia dependent, type A, and the type B, which preferably uses glutamine. Absent in humans and present in trypanosomatids, AS-A was worthy of exploring as a potential drug target candidate. Appealingly, it was reported that AS-A was essential in Leishmania donovani, making it a promising drug target. In the work herein we demonstrate that Leishmania infantum AS-A, similarly to Trypanosoma spp. and L. donovani, is able to use both ammonia and glutamine as nitrogen donors. Moreover, we have successfully generated LiASA null mutants by targeted gene replacement in L. infantum, and these parasites do not display any significant growth or infectivity defect. Indeed, a severe impairment of in vitro growth was only observed when null mutants were cultured in asparagine limiting conditions. Altogether our results demonstrate that despite being important under asparagine limitation, LiAS-A is not essential for parasite survival, growth or infectivity in normal in vitro and in vivo conditions. Therefore we exclude AS-A as a suitable drug target against L. infantum parasites.
authors.affiliation: Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.|Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Faria
authors.affiliation: Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.|Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Loureiro
authors.affiliation: Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.|Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Santarém
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.|Protein Crystallography Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Macedo-Ribeiro
authors.affiliation: Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.|Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Tavares
authors.affiliation: Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.|Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.|Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
authors.forename: Anabela
authors.initials: A
authors.lastname: Cordeiro-da-Silva
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001216:Asparagine / Q000378:metabolism; D001217:Aspartate-Ammonia Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D018314:Leishmania infantum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D007898:Leishmaniasis, Visceral / Q000469:parasitology*; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D015800:Protozoan Proteins; D005973:Glutamine; D001216:Asparagine; D000641:Ammonia; D001217:Aspartate-Ammonia Ligase