List of Figures with captions

Figure 1 A) Structure of FadL: The α-helices of the extracellular region forming the opening of a hydrophobic groove are shown in orange. Inside the protein, several residues that can interact from the binding pocket are shown in red. The hatch domain of the intracellular region is shown in blue. Finally, one of the β-strands (strand 3 or S3), presents a bend or a kink, shown in green, that leads to the formation of an opening in the intramembrane surface of the protein. B) Transport mechanism of FadL: Schematic representation of the transport mechanism of FadL proposed by Lepore et al., 2011. The yellow box represents the bilipid layer and the red hexagons the lipopolysaccharide layer.
Figure 2 Bacterial fatty acid import systems: A) In certain Gram-negative bacteria a membrane-associated acyl-CoA synthetase imports the fatty acids to the cytosol in the form of acyl-CoA, a process known as vectorial acylation. B) In Gram-positive bacteria, single proteins have been identified in organisms such as R. jostii andM. tuberculosis which may be able to import free fatty acids into the cells, which will be later activated for their metabolization.C) In M. tuberculosis, the multiprotein complex Mce has been identified. The figure shows a hypothetical model adapted from Nazarova et al., 2019.
Figure 3 Structure of the AcrAB-TolC complex: The multiprotein complex AcrAB-TolC spans from the inner to the outer membrane.
Figure 4 Structure of Fat1: Fat1 presents two transmembrane domains and two domains which are partially integrated in the membrane. ATP/AMP binding domains are found near the two latter domains. A VLACS domain is found further in the C-terminal region. Finally, the soluble Faa1 has been observed to interact with the C-terminus of this protein to activate the imported fatty acids.
Figure 5 Intracellular trafficking of fatty acids in yeast cells: Simplified fatty acid transport routes in S. cerevisiaebased on current knowledge. Both plasma membrane transport processes and intracellular trafficking routes are showed.
Figure 6 Intracellular trafficking of fatty acids in microalgae cells: Fatty acid intracellular trafficking routes in C. reinhardtii. No transport system has been described for the outer plastid membrane and for the export of free fatty acids to the extracellular media.