Type 4 Secretion Systems (T4SS)

These systems are present in both Gram-negative and Gram- positive bacteria. They form multi-megaDalton machines embedded in membranes and are responsible for the secretion of both proteins and nucleic acid substrates. They play major roles in pathogenicity of, for example, Helicobacter pylori, the causative agent of ulcers. They also mediate transfer of plasmid DNAs during conjugation, a process that leads to the spread of antibiotics resistance genes. T4S systems are composed of 12 proteins named VirB1-11 and VirD4 that assemble into a formidable nanomachine of more than 3 megaDalton in size and spanning the two membranes of Gram-negative bacteria.
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Download a recent review and our landmark papers in Nature and Science. Costa TR, Ilangovan A, Ukleja M, Redzej A, Santini JM, Smith TK, Egelman EH, Waksman G (2016). Structure of the Bacterial Sex F Pilus Reveals an Assembly of a Stoichiometric Protein-Phospholipid Complex. Cell. 166(6):1436-1444.e10 Trokter M, Felisberto-Rodrigues C, Christie PJ and Waksman G (2014). Recent advances in the structural and molecular biology of type IV secretion systems. Curr Opin Struct Biol. 2014 Aug;27:16-23. doi: 10.1016/ Epub 2014 Apr 5.  Low HH, Gubellini F, Rivera-Calzada A, Braun N, Connery S, Dujeancourt A, Lu F, Redzej A, Fronzes R, Orlova EV, Waksman G (2014). Structure of a type IV secretion system. Nature. 2014 Apr 24;508(7497):550-3. doi: 10.1038/nature13081. Epub 2014 Mar 9 Wallden K, Rivera-Calzada A, G. Waksman (2010). Type IV secretion systems: versatility and diversity in function. Cell Microbiol. Sep 1;12(9):1203-12. Review Chandran, R. Fronzes, S. Duquerroy, N. Cronin, J. Navaza, and G. Waksman (2009). Crystal structure of the outer membrane complex of a type IV secretion system. Nature. 462:1011-1015 R. Fronzes, E. Schaefer, H. Saibil, E. Orlova and G. Waksman (2009). Structure of type IV secretion core complex. Science. 323:266-268. Copyleft notice: The text of this webpage is available for modification and reuse under the terms of the Creative Commons Attribution-Sharealike 3.0 Unported License and the GNU Free Documentation License.
Type 4 Secretion Systems Pilus biogenesis