Role of a conserved arginine residue during catalysis in serine palmitoyltransferase.

摘要: All sphingolipid-producing organisms require the pyridoxal 5'-phosphate (PLP)-dependent serine palmitoyltransferase (SPT) to catalyse first reaction on de novo sphingolipid biosynthetic pathway. SPT is a member of alpha oxoamine synthase (AOS) family that catalyses Claisen-like condensation palmitoyl-CoA and L-serine form 3-ketodihydrosphingosine (KDS). Protein sequence alignment across various species reveals an arginine residue, not involved in PLP binding, be strictly conserved all prokaryotic SPTs, lcb2 subunits eukaryotic SPTs members AOS family. Here we use UV-vis spectroscopy site-directed mutagenesis, combination with substrate analogue, show equivalent residue (R370) from Sphingomonas wittichii required key PLP:L-serine quinonoid intermediate condenses thus plays essential role enzyme catalysis.