The scission of lipid membranes is a common biological process, often mediated by a set of protein complexes called the ESCRTs. The ESCRT machinery, commonly used in cellular activities such as cell division, is hijacked by the human immunodeficiency virus (HIV) to exit infected cells. Although it is well known that two of the three primary components of the ESCRT complex, ESCRTI and ESCRTIII are involved in the exit of HIV from the cell, the role of the ESCRTII component is a subject of scientific debate. The interaction between the ESCRTs and Gag is fleeting, lasting from a few seconds to a few minutes, which makes it difficult for these interactions to be studied with a fluorescent microscope.

In this project, I developed colocalisation analysis and single particle tracking methods to study the association between budding HIV virions and the ESCRTII complex. Our findings show the first visual evidence of the association between the ESCRTII protein EAP45 and the HIV protein Gag. This project was done in collaboration with The Lever Lab, who devised the research question and performed the virology and biochemical work.

Read more about this exciting project in our preprint.

eap45-track

This composite shows the workflow for tracking two simultaneously moving particles, ESCRTII (magenta) and HIV-Gag (cyan). The frame of reference is centred around the HIV-Gag particle for each frame such that it is stationary over time, and the motion of the ESCRTII (magenta) particle is plotted relative to the new frame of reference. This allows for a more clear visualisation of the relative position of two moving particles.