An activator for pyruvoyl‐dependent l‐aspartate α‐decarboxylase is conserved in a small group of the γ‐proteobacteria including Escherichia coli

Abstract

In bacteria, β-alanine is formed via the action of l-aspartate α-decarboxylase (PanD) which is one of the small class of pyruvoyl-dependent enzymes. The pyruvoyl cofactor in these enzymes is formed via the intramolecular rearrangement of a serine residue in the peptide backbone leading to chain cleavage and formation of the covalently-bound cofactor from the serine residue. This reaction was previously thought to be uncatalysed. Here we show that in Escherichia coli, PanD is activated by the putative acetyltransferase YhhK, subsequently termed PanZ. Activation of PanD both in vivo and in vitro is PanZ-dependent. PanZ binds to PanD, and we demonstrate that a PanZ(N45A) site-directed mutant is unable to enhance cleavage of the proenzyme PanD despite retaining affinity for PanD. This suggests that the putative acetyltransferases domain of PanZ may be responsible for activation to enhance the processing of PanD. Although panD is conserved among most bacteria, the panZ gene is conserved only in E. coli-related enterobacterial species including Shigella, Salmonella, Klebsiella and Yersinia. These bacteria are found predominantly in the gut flora where pantothenate is abundant and regulation of PanD by PanZ allows these organisms to closely regulate production of β-alanine and hence pantothenate in response to metabolic demand.

Genomewide landscape of gene–metabolome associations in Escherichia coli

“…YhhK knockout mutant exhibited strong similarity to several enzymes in pantothenate and coenzyme A biosynthesis ( panB , panC , panD, and panE ), with several differential metabolites in the coenzyme A biosynthesis pathway, including (R)‐pantoate and (R)‐pantothenate. Consistent with our data, YhhK was found to be an acetyl‐transferase activating PanD and recently annotated as PanZ (Nozaki et al , ; Stuecker et al , ). Similarly, metabolome profiling of ygfY deletion mutant featured common metabolic changes (Table EV3) to genes encoding subunits of succinate dehydrogenase (i.e., sdhB and sdhC) .…”

Acylation of Biomolecules in Prokaryotes: a Widespread Strategy for the Control of Biological Function and Metabolic Stress

“…In S. enterica, a GNAT homologue known as PanM (formerly YhhK) promotes cleavage and maturation of the L-aspartate-␣-decarboxylase zymogen (pro-PanD), an enzyme of the coenzyme A biosynthetic pathway (14,15). PanZ, the PanM homologue in E. coli, performs the same function in this bacterium (95,96).…”

Enhanced poly(3-hydroxypropionate) production via β-alanine pathway in recombinant Escherichia coli

“…The E . coli PanD is an unusual enzyme in that it requires pyruvate as a covalently bound, activated by the putative acetyltransferase PanZ [13]. No over-expressing of suitable PanZ in this study might be the reason of weak E .…”