Malonate decarboxylase of Pseudomonas putida is composed of five subunits

Abstract

Two different forms of malonate decarboxylase were purified from Pseudomonas putida. The active form was composed of the five different subunits α (60 kDa), β (33 kDa), γ (28 kDa), δ (13 kDa), and ϵ (30 kDa) and the inactive form was composed of the four subunits lacking the ϵ subunit. The former catalyzed the decarboxylation of malonate to acetate, but the latter could not, although it retained both activities of acetyl-CoA:malonate CoA transferase and malonyl-CoA decarboxylase. The δ subunit of the active form was acylated by the incubation with [2- 14C]malonyl-CoA, but the δ subunit of the inactive form was not labeled. From the above results and the N-terminal amino acid sequence analysis, it was concluded that the ϵ subunit was an essential subunit to function as malonyl-CoA:ACP transacylase, which was an indispensable component of the enzyme for the cyclic decarboxylation of malonate.