A PATHWAY OF THE AUTOTROPHIC CO2 FIXATION IN CHLOROFLEXUS-AURANTIACUS

Autotrophically grown cells of Chloroflexus aurantiacus B-3 were shown to possess activity of ATP-dependent malate lyase (acetylating CoA). ATP: malate lyase is supposed to be the specific enzyme of the cycle of the autotrophic CO2 fixation, in which pyruvate synthase, pyruvate phosphate dikinase, phosphoenol-pyruvate (PEP) carboxylase and malate dehydrogenase are involved as well. The main product of the CO2 fixation cycle is glyoxylate, which could further be converted into 3-phosphoglyceric acid (3-PGA) in the reactions of either glycerate or serine pathway. The enzymes of both pathways were detected in C. auratiacus B-3. The results of the in vivo studies of glyxoylate and glycine metabolism, as well as the inhibitor analysis using fluoroacetate (FAc), isonicotinic acid hydrazide (INH), and 4-aminopterin (4-AP) confirm the operation of the proposed pathway in Chloroflexus.