title: Brucella abortus depends on pyruvate phosphate dikinase and malic enzyme but not on Fbp and GlpX fructose-1,6-bisphosphatases for full virulence in laboratory models.
abstract: The brucellae are the etiological agents of brucellosis, a worldwide-distributed zoonosis. These bacteria are facultative intracellular parasites and thus are able to adjust their metabolism to the extra- and intracellular environments encountered during an infectious cycle. However, this aspect of Brucella biology is imperfectly understood, and the nutrients available in the intracellular niche are unknown. Here, we investigated the central pathways of C metabolism used by Brucella abortus by deleting the putative fructose-1,6-bisphosphatase (fbp and glpX), phosphoenolpyruvate carboxykinase (pckA), pyruvate phosphate dikinase (ppdK), and malic enzyme (mae) genes. In gluconeogenic but not in rich media, growth of ΔppdK and Δmae mutants was severely impaired and growth of the double Δfbp-ΔglpX mutant was reduced. In macrophages, only the ΔppdK and Δmae mutants showed reduced multiplication, and studies with the ΔppdK mutant confirmed that it reached the replicative niche. Similarly, only the ΔppdK and Δmae mutants were attenuated in mice, the former being cleared by week 10 and the latter persisting longer than 12 weeks. We also investigated the glyoxylate cycle. Although aceA (isocitrate lyase) promoter activity was enhanced in rich medium, aceA disruption had no effect in vitro or on multiplication in macrophages or mouse spleens. The results suggest that B. abortus grows intracellularly using a limited supply of 6-C (and 5-C) sugars that is compensated by glutamate and possibly other amino acids entering the Krebs cycle without a critical role of the glyoxylate shunt.
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Amaia
authors.initials: A
authors.lastname: Zúñiga-Ripa
authors.affiliation: Research Unit in Biology of Microorganisms-URBM, NARILIS, UNAmur, Namur, Belgium.
authors.forename: Thibault
authors.initials: T
authors.lastname: Barbier
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Conde-Álvarez
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Estrella
authors.initials: E
authors.lastname: Martínez-Gómez
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Leyre
authors.initials: L
authors.lastname: Palacios-Chaves
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Gil-Ramírez
authors.affiliation: Grupo de Sanidad Animal, Instituto de Agrobiotecnología (CSIC-Universidad Pública de Navarra-Gobierno de Navarra), Campus de Arrosadía, Pamplona, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Grilló
authors.affiliation: Research Unit in Biology of Microorganisms-URBM, NARILIS, UNAmur, Namur, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Letesson
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain.
authors.forename: Maite
authors.initials: M
authors.lastname: Iriarte
authors.affiliation: Departamento de Microbiología e Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain imoriyon@unav.es.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Moriyón
mesh_terms: D000818:Animals; D002003:Brucella abortus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D002006:Brucellosis / Q000382:microbiology* / Q000473:pathology; D002244:Carbon / Q000378:metabolism; D004195:Disease Models, Animal; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D051379:Mice; D011772:Pyruvate, Orthophosphate Dikinase / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D002244:Carbon; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+); D011772:Pyruvate, Orthophosphate Dikinase; D006597:Fructose-Bisphosphatase