Knowns and Unknowns of Vitamin B ₆ Metabolism in Escherichia coli

Abstract

Vitamin B6 is an ensemble of six interconvertible vitamers: pyridoxine (PN), pyridoxamine (PM), pyridoxal (PL), and their 5′-phosphate derivatives, PNP, PMP, and PLP. Pyridoxal 5′-phosphate is a coenzyme in a variety of enzyme reactions concerning transformations of amino and amino acid compounds.

Characterization of the Escherichia coli pyridoxal 5′‐phosphate homeostasis protein (YggS): Role of lysine residues in PLP binding and protein stability

“…The concentration of free PLP in the cell is low since most of this cofactor is bound to proteins. 4 Therefore, a signaling protein whose role was to sense PLP levels should have a high affinity for this cofactor. The binding of PLP to YggS, and the consequent changes in protein conformation or flexibility, may regulate its interactions with other cellular components involved in vitamin B 6 homeostasis.…”

“…Some features of YggS, such as the high affinity for PLP and the possible change in conformation and/or flexibility induced by PLP binding, together with the striking results obtained in the in vivo experiments, point toward a role of YggS as a component of an unknown regulatory pathway. The concentration of free PLP in the cell is low since most of this cofactor is bound to proteins 4 . Therefore, a signaling protein whose role was to sense PLP levels should have a high affinity for this cofactor.…”

“… 4 How PLP is provided to PLP‐dependent enzymes while maintaining a low concentration in its free form remains unknown even in the best‐studied model organisms such as Escherichia coli. 3 , 4 Recent studies have shown that the PLP Homeostasis Protein (PLPHP), named YggS in E . coli and previously named PROSC in humans, a member of the COG0325 family, is somehow ubiquitously involved in PLP homeostasis.…”

Tailored Pyridoxal Probes Unravel Novel Cofactor‐Dependent Targets and Antibiotic Hits in Critical Bacterial Pathogens

“…While the intriguing perspective on wt cell labelling is followed up later in this study, we here focused on E. coli K12 ΔpdxJ for quantitative LC‐MS/MS analysis to compare the performance directly with S. aureus . For this, we utilized the refined workflow as described above and incubated all 13 probes individually with live cells at 100 μM for 2 h. A closer inspection of the corresponding volcano plots revealed a significant enrichment of 38 enzymes comprising 61 % of functionally assigned or predicted PLP ‐DEs in E. coli (Figure 2E, F, Figure SI6, Table SI2) [30, 33] …”

Maßgeschneiderte Pyridoxal‐Sonden enthüllen neue Cofaktor‐abhängige Enzyme und antibiotische Treffer in kritischen bakteriellen Krankheitserregern

“…Dazu verwendeten wir den oben beschriebenen verfeinerten Arbeitsablauf und inkubierten alle 13 Sonden einzeln mit lebenden Zellen in einer Konzentration von 100 μM für 2 Stunden. Eine genauere Betrachtung der entsprechenden Volcano‐Plots zeigte eine signifikante Anreicherung von 38 Enzymen, was einem Anteil von 61 % der funktionell zugeordneten oder vorhergesagten PLP ‐DEs in E. coli entspricht (Abbildung 2E, F, Abbildung SI6, Tabelle SI2) [30, 33] . Bemerkenswert ist, dass diese Abdeckung die individuellen Labellingpräferenzen aller Sonden widerspiegelt, was zeigt, dass ihre Vielfalt der Schlüssel zum Zugang zu den verschiedenen Bindungsstellen der Enzyme ist.…”