A TonB-dependent transporter is required for secretion of protease PopC across the bacterial outer membrane

• Published in: Nature communications 2019-03, Vol.10 (1), p.1360-1360, Article 1360
• Main Authors: Gómez-Santos, Nuria, Glatter, Timo, Koebnik, Ralf, Świątek-Połatyńska, Magdalena Anna, Søgaard-Andersen, Lotte
• Format: Article
• Language: English
• Subjects: 14/63; 38/1; 38/111; 38/70; 38/77; 38/88; 38/90; 42/70; 631/326; 631/45; 631/80/2023; 631/80/313; 631/80/313/2376; 82/58; 82/80; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriocins; Biological Transport; Cell Membrane - metabolism; E coli; Escherichia coli - classification; Escherichia coli - genetics; Escherichia coli - metabolism; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Humanities and Social Sciences; Imports; Isoenzymes - genetics; Isoenzymes - metabolism; Life Sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; multidisciplinary; Myxococcus xanthus; Myxococcus xanthus - classification; Myxococcus xanthus - genetics; Myxococcus xanthus - metabolism; Nutrients; Peptide Hydrolases - genetics; Peptide Hydrolases - metabolism; Periplasm; Periplasm - metabolism; Phylogeny; Protease; Proteinase; Proteins; Proton-Motive Force; Protonmotive force; Protons; Science; Science (multidisciplinary); Secretion
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09366-9

TonB-dependent transporters (TBDTs) are ubiquitous outer membrane β-barrel proteins that import nutrients and bacteriocins across the outer membrane in a proton motive force-dependent manner, by directly connecting to the ExbB/ExbD/TonB system in the inner membrane. Here, we show that the TBDT Oar in Myxococcus xanthus is required for secretion of a protein, protease PopC, to the extracellular milieu. PopC accumulates in the periplasm before secretion across the outer membrane, and the proton motive force has a role in secretion to the extracellular milieu. Reconstitution experiments in Escherichia coli demonstrate that secretion of PopC across the outer membrane not only depends on Oar but also on the ExbB/ExbD/TonB system. Our results indicate that TBDTs and the ExbB/ExbD/TonB system may have roles not only in import processes but also in secretion of proteins. TonB-dependent transporters (TBDTs) are outer membrane proteins that import nutrients and bacteriocins in bacteria. Here, Gómez-Santos et al. show that a TBDT is required for secretion of a protease in Myxococcus xanthus , suggesting that some TBDTs may be involved in protein secretion.