York Research Spotlight : Luke Mackinder

Department: Biology

Current project: Creating a spatially defined, multidimensional, protein interactome of the eukaryotic algal CO2 concentrating mechanism

Advice to aspiring scientists: ‘Having interests outside of academia actually really helps to relax. Its good to have a break from your work. It allows you to be more creative and focused when you come back to do science’

Selected publication: Mackinder et al. (2017) A spatial interactome reveals the protein organization of the algal CO2 concentrating mechanism. (Cell)

While there are many different and extremely complex areas of study which our University’s academic staff devote their time to, the people behind the research are similarly just as unique as the scientific questions they ask. Dr Luke Mackinder is certainly no exception. The surfer and mountain biker has devoted his academic career to studying eukaryotic algae and their ability to photosynthesise much more efficiently than most land plants. Their improved photosynthetic capability means that these microscopic organisms fix as much as 40% of the globes CO2, making them especially important in current times when anthropogenically caused CO2 emissions are higher than ever.

Luke Mackinder enjoying the single track climbs, Emma McCrary trail, Santa Cruz Mountains, California, U.S.A. © 2015 Shawn Boye

The eukaryotic green algae of interest to Dr Mackinder live mainly in bodies of water and have the ability to collect CO2 in a specific region of their cell, called a pyrenoid, using a process known as a CO2 concentrating mechanism (CCM). While the ability to concentrate CO2 within a particular compartment was not particularly useful 3 billion years ago when the planet had much higher CO2 levels and the first photosynthetic organisms evolved to absorb the greenhouse gas, the current lower levels of atmospheric CO2 mean that green algae must now actively compile CO2 in high concentrations where photosynthesis occurs. If CCMs did not exist and these organisms did not concentrate CO2 into specialised compartments, these photosynthetic organisms would consequently end up fixing high amounts of O2 instead, in a process known as photorespiration. Through photorespiration, the organism does not gain but wastes energy. While the loss of energy via photorespiration still occurs at a low level, the presence of CCMs prevents the process from occurring in frequencies that would be fatal.

 A recent hypothesis proposed by Dr Mackinder and his colleagues is the result of research into a model species of eukaryotic algae known as Chlamydomonas reinhardtii. This algal species has a very effective CCM with the pyrenoid critical for it being able to perform highly efficient photosynthesis. The newly proposed hypothesis postulates that the pyrenoid is liquid based rather than crystalline as previously theorised. The implications of the pyrenoid being liquid would be that C.reinhardtii is better able to quickly adapt to changing environmental CO2 concentrations than previously thought. In the case of a crystalline pyrenoid, adaptation to changing CO2 would be time-consuming and would use energy. A liquid pyrenoid also means that during replication the organism could produce 2 pyrenoids via fission of the original pyrenoid on the time scale of mere seconds.

A transmission electron microscope image of a C.reinhardtii specimen. The model species worked on by Dr Mackinder Image: Dartmouth College

While there initially may not seem to be any immediate applications of this research to benefit humans, Dr Mackinder and colleagues propose the possibility of introducing CCMs into higher plant life such as agricultural crops. Introduction of these mechanisms could potentially lead to substantially higher photosynthetic rates by such plants, which may produce higher crop yields in order to feed an ever-growing human population.

Just recently awarded the 2018 President’s medal for cell biology by the Society for Experimental Biology which he will be accepting in Florence this July, Dr Mackinder is one of the many devoted scientists on campus whose research into the unknown could have potentially monumental implications not only for humanity but for the planet as a whole.

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