Bacterial Protein Transport Pathways and Analogous Conserved Pathways in Eukaryotes

Approximately 30% of the proteins in bacteria are exported to the cell surface. The export process is crucial for bacterial growth and survival, protein biogenesis, membrane function, signaling, lipid synthesis, and metabolism. This review will present recent advances in the export of proteins to the periplasm and outer membrane, primarily in Gram-negative bacteria and discuss how proteins are targeted and inserted into the inner membrane. Many systems are used for this process, which include the secretion (Sec) system, the insertase YidC, the twin-arginine translocation (Tat) system, the β-barrel assembly machinery (BAM) insertase, and the localization of lipoprotein (Lol) system, in Gram-negative bacteria. The accumulating evidence reveals that many of the fascinating insertion/translocation components used in bacteria have found their way into eukaryotic cells through evolution, now playing crucial roles in ER, mitochondria, and chloroplasts.