Plants may look simple, however when it comes to cell division things are more complicated than in animals; Lisa Smith's project team seek to understand how a plant-specific molecular motor powers successful cell division
Despite the discovery of cells in plants 350 years ago, and the importance of plant cell division to life on Earth, many aspects of cell division are simply not understood in plants. Cell division is more complicated in plants where the daughter cells are separated by centrifugal construction of a new cell membrane and cell wall from the centre of the division plane, than in animals and bacteria where cell separation occurs via constriction of the cell membrane. Amongst the gaps in our knowledge of plant cell division are key details of how the new cell membranes and walls are assembled to split a mother cell into two daughter cells. The cellular structures used to separate DNA into the daughter cells also differ between plants and animals, with these differences reflected by changes in the molecular motors that move cell components and construct the scaffolding needed for cell division.
A diverse array of molecular motors mediates cell division by directionally moving along structural microtubule chains. These motor proteins have a microtubule-binding kinesin domain separated from a cargo-binding domain by a stalk. The kinesin domain ‘walks’ along the microtubules. While the kinesin domain is conserved between proteins and species, the cargo-binding domains are highly divergent even within a single species, reflecting functional diversity. Despite the involvement of many kinesins in the extensive rearrangements required for cell division, the functions of most remain unknown.
In the research funded by the Leverhulme Trust, we seek to understand how a plant-specific molecular motor powers successful cell division. We have recently identified a plant kinesin which is extremely interesting because it affects plant development and is one of two kinesins in the model plant Arabidopsis that contains a cargo-binding domain that can potentially bind carbohydrates and peptides. This kinesin could therefore bind both cytoskeletal components and cell wall carbohydrates. We speculate that this kinesin may represent an important adaption of plants to terrestrial life through a key conserved function in cell wall formation during cell division.
In this project, we have four objectives which will help us to understand the function of this motor protein. Firstly, we will investigate the localisation of the kinesin in relation to key cell structures during cell division. Secondly, we will identify why developmental defects arise when the kinesin is absent. We will dissect the function of each part of the protein for our third objective. And finally, we will determine whether the kinesin can bind to carbohydrates and identify interacting compounds.