OprF functions as a latch to direct Outer Membrane Vesicle release in Pseudomonas aeruginosa.

Bacterial Outer Membrane Vesicles (OMVs) contribute to virulence, competition, immune avoidance and communication. This has led to great interest in how they are formed. To date, investigation has focused almost exclusively on what controls the initiation of OMV biogenesis. Regardless of the mechanism of initiation, all species face a similar challenge before an OMV can be released: How does the OM detach from the underlying peptidoglycan (PG) in regions that will ultimately bulge and then vesiculate? The OmpA family of OM proteins (OprF in P. aeruginosa) is widely conserved and unusually abundant in OMVs across species considering their major role in PG attachment. OmpA homologs also have the interesting ability to adopt both PG-bound (two-domain) and PG-released (one-domain) conformations. Using targeted deletion of the PG-binding domain we showed that loss of cell wall association, and not general membrane destabilization, is responsible for hypervesiculation in OprF-modified strains. We therefore propose that OprF functions as a 'latch', capable of releasing PG in regions destined to become OMVs. To test this hypothesis, we developed a protocol to assess OprF conformation in live cells and purified OMVs. While >90% of OprF proteins exist in the two-domain conformation in the OM of cells, we show that the majority of OprF in OMVs is present in the one-domain conformation. With this work, we take some of the first steps in characterizing late-stage OMV biogenesis and identify a family of proteins whose critical role can be explained by their unique ability to fold into two distinct conformations.

TikTok: An Emergent Opportunity for Teaching and Learning Science Communication Online.

Increasing use of social media during the COVID-19 pandemic practice of social distancing has emphasized the value and power of effective science communication through social media. As such, it has become equally important to teach and learn how to use social media accurately and effectively for science communication. In response, we developed an activity to use the social media platform TikTok to both model and build effective 21st century science communication skills. TikTok is a short-form video sharing platform whose popularity sharply increased during the COVID-19 pandemic. By using the short, focused video style of TikTok, we modeled effective social media science communication practices to teach basic science concepts and laboratory techniques. At the end of the semester, students were then challenged to create their own informative and engaging TikToks about their team's research projects to practice effective science communication. Here we share our approach and several TikTok best practices for effective and engaging science communication teaching and learning, along with example videos created during this process.