PilQs are involved in many important surface activities in microorganisms and have been recently reported to be involved in the peptidoglycan biosynthesis in E. coli. We found that the elongation of PilQ was significantly enhanced when the large base plate-like crystal was present, and that the crystals were found to be associated with pilus. DNA is one of the most important molecules in living cells. The pilus here was not only involved in cell surface display but also associated with DNA, and thus was involved in transmembrane transport. By using atomic force microscopy(AFM), we first observed that the height of the monomers was about 6.5 nm, which was close to the lateral height of DNA. This indicated that DNA might be associated with the TFP components. To verify this possibility, we forced DNA into the AFM apparatus and only observed the dependence of the length and the force balance on the height ratio in the presence of the large base plate-like crystal. These results indicated that the TFP components were involved in the transport of DNA through the surface of living bacteria. Here, we used the C12E8 to block the hydrophilic head of the TFPs. By titration, we found the maximum hydrophile of the stabilization process. Wild type (WT) and site mutants were then incubated with C12E8 and following AFM imaging, we found the bath-like of stabilized TFPs in the WT, while no large base plate-like crystals and no interactions of C12E8 with polymer ion through the maximum hydrophile of the system could be observed for mutants. This demonstrates that the stabilization of TFP might be associated with the hydrophilic head of the TFP polymer.
Nanopore fabrication has inspired scientists to explore their potential applications in biology. The applications of nanopores may range from single molecule detection  to DNA sequencing  and drug transfection  based on signal transduction and biophysical characteristics. Here, we chose to make a nanopore in the outer membrane of E. coli strain. The type IV pilus (TFP), as a well known nanostructure, was grown on the cell inner membrane by means of polymer growth and subsequent dissolution, forming a hole that was then expanded by the addition of an amphipathic ruthenium compound. d2c66b5586