The glycerol-3-phosphate dehydrogenases GpsA and GlpD constitute the oxidoreductive metabolic linchpin for Lyme disease spirochete host infectivity and persistence in the tick

Abstract

We have identified GpsA, a predicted glycerol-3-phosphate dehydrogenase, as a virulence factor in the Lyme disease spirochete Borrelia (Borreliella) burgdorferi: GpsA is essential for murine infection and crucial for persistence of the spirochete in the tick. B. burgdorferi has a limited biosynthetic and metabolic capacity; the linchpin connecting central carbohydrate and lipid metabolism is at the interconversion of glycerol-3-phosphate and dihydroxyacetone phosphate, catalyzed by GpsA and another glycerol-3-phosphate dehydrogenase, GlpD. Using a broad metabolomics approach, we found that GpsA serves as a dominant regulator of NADH and glycerol-3-phosphate levels in vitro, metabolic intermediates that reflect the cellular redox potential and serve as a precursor for lipid and lipoprotein biosynthesis, respectively. Additionally, GpsA was required for survival under nutrient stress, regulated overall reductase activity and controlled B. burgdorferi morphology in vitro. Furthermore, during in vitro nutrient stress, both glycerol and N-acetylglucosamine were bactericidal to B. burgdorferi in a GlpD-dependent manner. This study is also the first to identify a suppressor mutation in B. burgdorferi: a glpD deletion restored the wild-type phenotype to the pleiotropic gpsA mutant, including murine infectivity by needle inoculation at high doses, survival under nutrient stress, morphological changes and the metabolic imbalance of NADH and glycerol-3-phosphate. These results illustrate how basic metabolic functions that are dispensable for in vitro growth can be essential for in vivo infectivity of B. burgdorferi and may serve as attractive therapeutic targets.

Riboflavin salvage by Borrelia burgdorferi supports carbon metabolism and is essential for survival in the tick vector

“…In our analysis, glycerol 3‐phosphate (Gro3P) was found to be the metabolite with the greatest fold change difference between the Δ bb0318 mutant and wild‐type B. burgdorferi (Figure 1b and Table S2). In B. burgdorferi , Gro3P is generated by the reduction of the glycolysis intermediate dihydroxyacetone phosphate (DHAP) by GpsA/BB0368 (Drecktrah et al, 2022) and/or phosphorylation of imported glycerol by GlpK/BB0241, a putative glycerol kinase (Schwan et al, 2003). In addition, Gro3P is believed to be converted to DHAP by a putative Gro3P dehydrogenase, GlpD/BB0243 (Fraser et al, 1997; Gherardini et al, 2021).…”

“…It was recently demonstrated that the complementary activities of GlpD and GpsA control the intracellular pool of Gro3P (Drecktrah et al, 2022). Therefore, beyond decreased activity of GlpD due to FAD deficiency, we explored the possibility that the accumulation of Gro3P in the absence of bb0318 may have resulted from dysregulation of glpD or gpsA expression.…”

“…This result led to the discovery of the contribution of the BB0316‐BB0319 riboflavin transport system to the expression of the glycerol utilization gene glpD and to experimental definition of GlpD as an FAD‐dependent, peripheral membrane glycerol 3‐phosphate dehydrogenase. Together these findings suggested that Gro3P accumulation in Δ bb0318 B. burgdorferi was the consequence of both reduced GlpD protein abundance and activity and therefore an imbalance in the GpsA/GlpD driven reciprocal interconversion of Gro3P and DHAP (Drecktrah et al, 2022) favoring the conversion of DHAP to Gro3P by GpsA. A shift toward Gro3P accumulation was recently demonstrated for a B. burgdorferi mutant lacking glpD (Drecktrah et al, 2022), providing further support for the proposed mechanism of increased levels of Gro3P in Δ bb0318 B. burgdorferi .…”

“…Together these findings suggested that Gro3P accumulation in Δ bb0318 B. burgdorferi was the consequence of both reduced GlpD protein abundance and activity and therefore an imbalance in the GpsA/GlpD driven reciprocal interconversion of Gro3P and DHAP (Drecktrah et al, 2022) favoring the conversion of DHAP to Gro3P by GpsA. A shift toward Gro3P accumulation was recently demonstrated for a B. burgdorferi mutant lacking glpD (Drecktrah et al, 2022), providing further support for the proposed mechanism of increased levels of Gro3P in Δ bb0318 B. burgdorferi .…”

Metabolic network models ofGardnerellapangenome identify interactions in the vaginal environment

“…One such essential gene, gpsA , is a predicted glycerol-3-phosphate dehydrogenase, and it is involved in phospholipid synthesis. Previous research has identified gpsA as a virulence factor in Lyme disease, as well as enhancing nasopharyngeal colonization of Streptococcus pneumoniae (Drecktrah et al, 2022; Green et al, 2021). Another conserved essential gene, suhB , is an inositol monophosphatase.…”