Components and Key Regulatory Steps of Lipid Biosynthesis in Actinomycetes

Abstract

The biochemical steps in fatty acid synthesis are highly conserved in bacteria and in most organisms. However, the data provided by the massive genomic sequencing revealed a surprising amount of diversity in the genes, enzymes, and genetic organization of the components responsible for bacterial lipid synthesis, with these differences being even more striking in the order Actinomycetales. Fatty acid biosynthesis is energetically very expensive for the cell; therefore, adjusting the rate of fatty acid synthesis, in order to maintain membrane lipid homeostasis, is a key factor for bacterial survival. Bacteria have evolved sophisticated and diverse mechanisms to finely control the expression of the genes responsible for the synthesis of fatty acids and, in some cases, also by regulating the activity of the pacemaker enzymes. In this chapter we summarize the main components of fatty acid biosynthesis and their regulation in different genera of actinomycetes, highlighting the main differences found between them and also with other bacteria. The main focus has been put into the acyl-CoA carboxylases, the fatty acid synthases, and on the regulatory elements that control these pathways.