Structural characterization of Escherichia coli phosphatidylserine decarboxylase

Abstract

Phosphatidylserine decarboxylase in Escherichia coli is one of a small group of pyruvoyl-dependent enzymes (Satre,. M., and Kennedy, E. P. (1978) J. Biol. Chem. 253, 479-483). The DNA sequence of the structural gene (psd) and partial protein sequence studies demonstrate that the enzyme contains two nonidentical subunits, α (M(r) = 7,332) and β (M(r) = 28,579), which are derived from a single proenzyme. These two subunits are blocked at their respective amino termini. Reduction of the enzyme with NaCNBH3 in the presence of radiolabeled phosphatidylserine resulted in association of the label with the α subunit. Similar reduction in the presence of ammonium ions exposed a new amino terminus for..