6aeo

Publication Abstract from PubMed

Type VI secretion system (T6SS), as a macromolecular system, is commonly found in Gram-negative bacteria and responsible for exporting effectors. T6SS consists of 13 core proteins. TssL is a component of the membrane complex and plays a pivotal role in T6SS. Here, we report the crystal structure of the C-terminal periplasmic domain of TssL (TssLCter) from Serratia marcescens FS14. The TssLCter (310-503) contain a five-stranded anti-parallel beta-sheet flanked by five alpha-helices and a short N-terminal helix. Structural comparisons revealed that it belongs to the OmpA-like family with a remarked difference in the conformation of the loop3-5. In OmpA-like family, the corresponding loop is located close to loop2-3, forming a cavity with a small opening together with the longest alpha5, whereas in TssLCter, loop3-5 flipped away from this cavity region. In addition, significant differences in the peptidoglycan (PG) binding site suggest that big conformational change must take place to accomplish the PG binding for TssLCter. Furthermore, a long flexible loop between helices alpha1 and alpha2 is unique in TssL. TssL would have a big conformational change during the delivery of the Hcp needle and effectors. So we speculate that the long flexible endows TssL the adaptation of its evolutionary new function.

Crystal structure of the periplasmic domain of TssL, a key membrane component of Type VI secretion system.,Wang X, Sun B, Xu M, Qiu S, Xu D, Ran T, He J, Wang W Int J Biol Macromol. 2018 Dec;120(Pt B):1474-1479. doi:, 10.1016/j.ijbiomac.2018.09.166. Epub 2018 Sep 26. PMID:30266644^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.