Abstract
Intrabacterial lipid Inclusions (ILI), known as oil/fat bodies or adiposomes, are organelles found in intracellular pathogens, such as mycobacteria. They are composed of neutral lipids, mainly triacylglycerol, surrounded by a phospholipid monolayer containing a wide array of proteins. In the past decade, several groups have fostered the research on elucidating the ILI composition though the combination of a large panel of broad-range techniques, including proteomics, lipidomics or metabolomics, portraying an unexpected level of complexity. Although ILI with their associated proteins are thought to play various roles related to the metabolism and storage of neutral lipids, membrane biosynthesis, reduction of cytotoxicity and signal transduction; their exact role and contribution in virulence, their origin and evolution remain largely unknown. This chapter aims to summarize the current knowledge on the biology of ILI, their occurrence and evolution. It also reports the latest achievements regarding the procedures used to prepare and purify ILI as well as to cutting-edge methods, such as proximity labelling to identify protein partners associated with ILI. The access to newly discovered ILI-associated partners and their possible link with pathogenicity opens the path to a tremendous and fascinating emerging area in the mycobacterial field.