Journal of Bacteriology
Journal of Bacteriology
5 years ago

Increased activity of cystathionine β-lyase suppresses 2-aminoacrylate stress inSalmonella enterica.

Melissa R Christopherson, Diana M Downs, Dustin C Ernst
Reactive enamine stress caused by intracellular 2-aminoacrylate accumulation leads to pleiotropic growth defects in a variety of organisms. Members of the well-conserved RidA/YER057c/UK114 protein family prevent enamine stress by enhancing the breakdown of 2-aminoacrylate to pyruvate. InSalmonella enterica, the disruption of RidA allows 2-aminoacrylate to accumulate and inactivate a variety of pyridoxal 5' -phosphate-dependent enzymes by generating covalent bonds with the enzyme and/or cofactor. This study was initiated to identify mechanisms that can overcome 2-aminoacrylate stress in the absence of RidA. Multi-copy suppressor analysis revealed that overproduction of the methionine biosynthetic enzyme cystathionine β-lyase (MetC; EC 4.4.1.8) alleviated the pleiotropic consequences of 2-aminoacrylate stress in aridAmutant strain. Degradation of cystathionine by MetC was not required for suppression ofridAphenotypes. The data support a model where MetC acts on a non-cystathionine substrate to generate a metabolite that reduces 2-aminoacrylate levels, representing a non-enzymatic mechanism of 2-aminoacrylate depletion.IMPORTANCERidA proteins are broadly conserved and have been demonstrated to deaminate 2-aminoacrylate and other enamines. 2-aminoacrylate is generated as an obligatory intermediate in several PLP-dependent reactions and, if it accumulates, damages cellular enzymes. This study identified a novel mechanism to eliminate 2-aminoacrylate stress that required the overproduction, but not the canonical activity, of cystathionine β-lyase. The data suggest a metabolite-metabolite interaction is responsible for quenching 2-aminoacrylate and emphasize the need for emerging technologies to probe metabolismin vivo.

Publisher URL: http://doi.org/10.1128/JB.00040-18

DOI: 10.1128/JB.00040-18

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