Bidirectional transport along microtubules: cooperation of Kif1C and dynein

Programme overview:
This MRC-funded doctoral training partnership (DTP) brings together cutting-edge molecular and analytical sciences with innovative computational approaches in data analysis to enable students to address hypothesis-led biomedical research questions. This is a 4-year programme whose first year involves a series of taught modules and two laboratory-based research projects that lead to an MSc in Interdisciplinary Biomedical Research. The first two terms consist of a selection of taught modules that allow students to gain a solid grounding in multidisciplinary science. Students also attend a series of masterclasses led by academic and industry experts in areas of molecular, cellular and tissue dynamics, microbiology and infection, applied biomedical technologies and artificial intelligence and data science. During the third and summer terms students conduct two eleven-week research projects in labs of their choice.

Project:
Our cells constantly produce proteins, nucleic acids and lipids which must be transported throughout the cell to the locations where they are needed. Microtubules act as the molecular highways on which motor proteins carry theses cargoes. These molecular motors typically travel in one direction: kinesins go towards the plus end of the microtubule, while dynein goes towards the opposite end.

Many cargoes simultaneously bind both dynein and kinesin, and move bidirectionally. Ideas have been put forward as to how cargo transport with opposing motors works. The tug-of-war model suggests that the ratio of forward and backward motors controls the overall direction, but research has shown that this is probably not the dominant mechanism for producing bi-directional transport, because removal one of these motors affects transport in both directions. This leads to the phenomenon of co-dependence - both forward and reverse motors are required for faithful transport in either direction, suggesting these motors support rather than fight one another. To move beyond the tug-of-war model, we need to examine how bi-directional motor complexes work. What are they key molecules, and key interactions? How do motors support each other? What allows a complex to swap directions?

We will first manufacture the proteins we are interested in using established insect cell expression techniques. We will attempt to reform bi-directional complexes and investigate their characteristics under a microscope. We aim to tease apart this complex to understand the importance of key molecules, and how they are providing directional bias. Simultaneously we will design experiments in live cells that can test key aspects of this transport mechanism. Finally we will attempt to recapitulate what we see down the microscope using computational simulation, with the hope to better our understanding of the process and elucidate new avenues for research.