Purine limitation prevents the exogenous pyridoxal 5′-phosphate accumulation of <i>Salmonella enterica yggS</i> mutants

Pyridoxal 5'-phosphate is the active form of vitamin B₆ and is an essential cofactor in all domains of life. PLP can be synthesized <i>de novo</i> or salvaged from the environment from one of the six B₆ vitamers. B₆ vitamer levels appear to be tightly regulated, and alterations in their levels can have deleterious effects, most notably being the development of B6-dependent epilepsy in humans. YggS homologs are broadly conserved across multiple organisms and considered to be involved in maintaining B₆ homeostasis, though no specific mechanism has been defined. The current study showed that the exogenous accumulation of PLP caused by a lack of YggS can be prevented by purine limitation. The demonstration that purine limitation impacts exogenous PLP accumulation separates one consequence of a <i>yggS</i> mutation for further study and contributes to continuing efforts to define the biochemical and physiological roles of the COG0325 family of proteins.