A way to identify archaellins in Halobacterium salinarum archaella by FLAG-tagging

In the current study, haloarchaea Halobacterium salinarum cells were transformed individually with each of the modified archaellin genes (flaA1, flaA2 and flaB2) containing an oligonucleotide insert encoding the FLAG peptide (DYKDDDDK). The insertion site was selected to expose the FLAG peptide on the archaella filament surface. Three types of transformed cells synthesizing archaella, containing A1, A2, or B2 archaellin modified with FLAG peptide were obtained. Electron microscopy of archaella has demonstrated that in each case the FLAG peptide is available for the specific antibody binding. It was shown for the first time that the B2 archaellin, like archaellins A1 and A2, is found along the whole filament length

Angiogenin Enhances Cell Migration by Regulating Stress Fiber Assembly and Focal Adhesion Dynamics

Angiogenin (ANG) acts on both vascular endothelial cells and cancer cells, but the underlying mechanism remains elusive. In this study, we carried out a co-immunoprecipitation assay in HeLa cells and identified 14 potential ANG-interacting proteins. Among these proteins, β-actin, α-actinin 4, and non-muscle myosin heavy chain 9 are stress fiber components and involved in cytoskeleton organization and movement, which prompted us to investigate the mechanism of action of ANG in cell migration. Upon confirmation of the interactions between ANG and the three proteins, further studies revealed that ANG co-localized with β-actin and α-actinin 4 at the leading edge of migrating cells. Down-regulation of ANG resulted in fewer but thicker stress fibers with less dynamics, which was associated with the enlargements of focal adhesions. The focal adhesion kinase activity and cell migration capacity were significantly decreased in ANG-deficient cells. Taken together, our data demonstrated that the existence of ANG in the cytoplasm optimizes stress fiber assembly and focal adhesion formation to accommodate cell migration. The finding that ANG promoted cancer cell migration might provide new clues for tumor metastasis research