LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany.
Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN, 47405, USA.
Sci Rep. 2018 Aug 1;8(1):11552. doi: 10.1038/s41598-018-29884-8.
Flagellin is amongst the most abundant proteins in flagellated bacterial species and constitutes the major building block of the flagellar filament. The proteins FliW and FliS serve in the post-transcriptional control of flagellin and guide the protein to the flagellar type III secretion system (fT3SS), respectively. Here, we present the high-resolution structure of FliS/flagellin heterodimer and show that FliS and FliW bind to opposing interfaces located at the N- and C-termini of flagellin. The FliS/flagellin/FliW heterotrimer is able to interact with FlhA-C suggesting that FliW and FliS are released during flagellin export. After release, FliW and FliS are recycled to execute a new round of post-transcriptional regulation and targeting. Taken together, our study provides a mechanism explaining how FliW and FliS synchronize the production of flagellin with the capacity of the fT3SS to secrete flagellin.
鞭毛蛋白是鞭毛细菌中最丰富的蛋白质之一，构成了鞭毛丝的主要结构单元。FliW 和 FliS 分别在鞭毛蛋白的转录后控制和引导蛋白进入鞭毛型 III 型分泌系统（fT3SS）中发挥作用。在这里，我们呈现了 FliS/鞭毛蛋白异二聚体的高分辨率结构，并表明 FliS 和 FliW 结合到鞭毛蛋白的 N 端和 C 端的相对接界面上。FliS/鞭毛蛋白/FliW 三聚体能够与 FlhA-C 相互作用，表明 FliW 和 FliS 在鞭毛蛋白输出过程中被释放。释放后，FliW 和 FliS 被回收，以执行新一轮的转录后调控和靶向。总之，我们的研究提供了一种机制，解释了 FliW 和 FliS 如何协调鞭毛蛋白的产生与 fT3SS 分泌鞭毛蛋白的能力。
