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 ⌬ppdK and ⌬mae mutants was severely impaired and growth of the double ⌬fbp-⌬glpX mutant was reduced. In macrophages, only the ⌬ppdK and ⌬mae mutants showed reduced multiplication, and studies with the ⌬ppdK mutant confirmed that it reached the replicative niche. Similarly, only the ⌬ppdK and ⌬mae 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.

A T4SS Effector Targets Host Cell Alpha-Enolase Contributing to Brucella abortus Intracellular Lifestyle

“…showed that during the chronic stage of infection, B. abortus replicates more efficiently in Alternatively Activated Macrophages (AAMs) than in Classically Activated Macrophages (CAM), and this preference was related to the ability of the pathogen to use the high availability of glucose in AAMs (Xavier et al, 2013). A metabolic mutational study carried out by Zuñiga-Ripa et al, indicated that gluconeogenesis is dispensable for Brucella during the intracellular stage of infection, whereas the triose phosphate pathway and the tricarbolixic cycle seems to be relevant during this stage, which is consistent with the idea that intracellular Brucella metabolizes 6C sugars and probably amino acids provided by the host (Zúñiga-Ripa et al, 2014). All these lines of evidence suggest that Brucella has evolved sophisticated mechanisms to ensure its persistence by manipulating the host-cell metabolism in its own benefits.…”

Brucella abortus Induces a Warburg Shift in Host Metabolism That Is Linked to Enhanced Intracellular Survival of the Pathogen

“…While classically activated M1 macrophages undergo a shift to Warburg-like metabolism upon exposure to pathogen-associated molecular patterns (PAMPs), Xavier and colleagues have shown that B. abortus preferentially infects alternatively activated M2 macrophages in mice, which have an opposite metabolic profile, showing decreased aerobic glycolysis (12). As recently noted (26,33), the physiological characteristics of host cell types and tissues colonized by Brucella spp. during the course of disease vary significantly, and it may be that lactate catabolism is important in some in vivo microenvironments but irrelevant in others.…”

Brucella Genital Tropism: What's on the Menu

“…On one hand, the rather high concentration of glycerol in Gerhard and Wilson's medium seems metabolically unnecessary and it has been interpreted to mean that non-nutritional properties, such as a proper control of the E h of the medium, could contribute (Gerhardt, 1958). On the other, even though impurities such as vitamins or amino acids in the reagent used in early studies cannot be ruled out (Gerhardt, 1958; Plommet, 1991), recent observations in vitro also support the complementarity role of glycerol (Zúñiga-Ripa et al, 2014). …”