Regulation and characterization of novel fimbriae in Salmonella enterica serovar Typhimurium.
Final Report Abstract
S. Typhimurium encodes for a large arsenal of adhesin factors. But since their expression is tightly regulated, most of them cannot be expressed under laboratory conditions. Consequently, for most of them little is known about binding partners, structure and the role in virulence. In a first attempt, we constructed a mutant where all operons or genes encoding for known or predicted adhesins were deleted and reintroduced single operons or genes encoding for adhesins into this strain. We hoped that this strategy will lead to expression of novel adhesins since it is known that expression of adhesins is coregulated. But unfortunately, this strategy did not prove successful. Therefore, we decided to express novel adhesins under control of a versatile Tet-on system. With this strategy, we successfully expressed for the first time the complete adhesiome of S. Typhimurium. We verified expression of adhesins by Western blotting and flow cytometry. Afterwards we visualized novel adhesins by a combinatory approach using atomic force microscopy (AFM) and transmission electron microscopy (TEM). We showed ultrastructural features of so far cryptic adhesins and demonstrated that they varied widely in morphology. We also demonstrated that fimbrial adhesins of S. Typhimurium cluster into two groups of thin and thick fimbriae. Interestingly, within a consensus tree generated by using amino acid sequences of chaperon proteins, fimbriae belonging to the group of thin fimbriae clustered into a single branch. We then furthermore used our versatile epression system for the controlled and timely expression of additional virulence factors of S. Typhimurium, EHEC and Y. enterocoliticas. We could restore motility in a flagella-deficient mutant of S. Typhimurium by heterogeneous expression of FliC as well as functionally express effector proteins of the SPI-1 and SPI-2 type 3 secretion systems of S. Typhimurium in Hela-cells. Additionally we were able to express InvA and YadA of Y. enterocolitica as well as fimbriae of an E. coli EHEC strain in both Salmonella and E. coli. In summary, we developed a versatile tool for functional expression of yet cryptic adhesins and virulence factors. This allowed us to express and visualize for the first time the complete adhesiome of S. Typhimurium. This leads to new opportunities for the characterization of novel adhesins in both Salmonella and other bacterial species and to answer the question, why these bacteria encode for such a large repertoire of adhesins and what role they play in pathogenicity.
Publications
- (2019) Std fimbriae-fucose interaction increases Salmonella-induced intestinal inflammation and prolongs colonization. PLoS pathogens 15 (7) e1007915
Suwandi, Abdulhadi; Galeev, Alibek; Riedel, René; Sharma, Samriti; Seeger, Katrin; Sterzenbach, Torsten; García Pastor, Lucía; Boyle, Erin C.; Gal-Mor, Ohad; Hensel, Michael; Casadesús, Josep; Baines, John F.; Grassl, Guntram A.
(See online at https://doi.org/10.1371/journal.ppat.1007915) - (2014). Salmonella enterica Serovar Typhi conceals the invasion-associated type three secretion system from the innate immune system by gene regulation. PLOS Pathogen, 10 (7): e1004207
Winter SE, Winter MG, Poon V, Keestra AM, Sterzenbach T, Faber F, Costa LF, Cassou F, Costa EA, Alves GE, Paixao TA, Santos RL, Bäumler AJ
(See online at https://doi.org/10.1371/journal.ppat.1004207) - (2017). Functional expression of the entire adhesiome of Salmonella enterica serotype Typhimurium. Sci. Rep., 7 (1): 10326
Hansmeier N, Miskiewicz K, Elpers L, Liss V, Hensel M, Sterzenbach T
(See online at https://doi.org/10.1038/s41598-017-10598-2) - (2018). A versatile remote control system for functional expression of bacterial virulence genesbased on the tetA promotor. Int. J. Med. Microbiol., 309 (1): 54-65
Schulte M, Sterzenbach T, Miskiewicz K, Elpers L, Hensel M, Hansmeier N
(See online at https://doi.org/10.1016/j.ijmm.2018.11.001)
