Studies on the central metabolism of Thermus aquaticus, an extreme thermophilic bacterium: Anaplerotic reactions and their regulation

Abstract

The physiology of Thermus aquaticus strain Z05 was investigated. Substantial evidence for gene and enzyme regulation in the central metabolism of this extreme thermophile was found. Two anaplerotic pathways were detected: (1) phosphoenolpyruvate carboxylase; (2) a glyoxylate shunt which proved to be essential for growth on pyruvate as well as acetate. The synthesis of isocitrate lyase and malate synthase were found to depend on a common control mechanism. Pronounced regulatory effects were observed on the activity of malic enzyme, pyruvate kinase and phosphoenolpyruvate carboxylase. The data could be fitted together into a picture of the metabolism during glycolysis and gluconeogenesis which shows how variations of enzyme levels and activities correlate with the apparent needs of the cell. Our results call attention to a peculiar metabolic analogy between T. aquaticus and Acinetobacter