PDX2

PDX2 is the putative glutamine amidotransferase subunit of the PDX1/PDX2-type pyridoxal phosphate (PLP) synthase complex that mediates de novo biosynthesis of vitamin B6 in Toxoplasma gondii (PMID:17222923). Its identification established that this parasite possesses an intact de novo PLP biosynthetic pathway rather than relying solely on salvage (PMID:17222923). Beyond this pathway-level assignment, no further mechanistic detail on PDX2 has been characterized in the available corpus.

1. 2006 Medium

   Whether Toxoplasma gondii could synthesize vitamin B6 de novo was resolved by identifying the components of its PLP synthase system, placing PDX2 as the glutamine amidotransferase subunit of this pathway.

   Evidence Biochemical characterization of the de novo PLP biosynthesis pathway in T. gondii, identifying PDX2 as a component of the PLP synthase complex

   PMID:17222923

   Open questions at the time

   • Direct enzymatic glutaminase activity of PDX2 not demonstrated
   • Physical interaction/stoichiometry with the PDX1 synthase subunit not established
   • No structural model or catalytic residue assignment