Investigating the thylakoid membrane: Journal Club with Guy Mayneord

In this week’s Journal Club, Grantham Scholar Guy Mayneord led a session based on his own supervisor Dr Matt Johnson’s work on photosynthesis. Here, explains the important role of the thylakoid membrane in this process, and questions surrounding our understanding of it.

This weeks paper

Visualising the dynamic structure of the plant photosynthetic membrane‘ by A. V. Ruban and M. P. Johnson

Guy Mayneord

Photosynthesis is possibly the most important chemical process for all of life on earth. Yet the thylakoid membrane in the chloroplast of plant cells, where photosynthesis occurs, has relatively little known about its dynamics, organisation, or responses to changes in the environment. Such changes in the environment can lead to drops in crop yields caused by damage to the machinery that carries out photosynthesis. In this journal club we discussed a recent review, co-written by my own supervisor Dr Matt Johnson which summarised our current understanding of the thylakoid membrane’s adaptive behaviour.

The paper discusses the multitude of adaptive mechanisms used by plant chloroplasts in order to adapt to light changes at the level of the thylakoid membrane. Such adaptations are currently reasonably understood, but there are still some areas that are under debate, or yet to be elucidated. For example, we understand the mechanisms by which light is captured in these systems, and filtered into molecular machines that convert this energy into a useful chemical form. However, when light intensity suddenly increases (eg, from clouds parting overhead) the resulting increase in captured energy can lead to damage of the molecular machinery.

In the longer term, if we can understand how these systems work, we may be able to reduce the energy costs of these adaptations by decreasing sensitivity, or fine tuning plants to specific environments where we could grow them. In addition, the lessons learned in these natural systems could be applied to the design of artificial protein-based solar cells, so that they too could adapt to different conditions while maintaining a high degree of efficiency.

Our discussion was mainly centred on the use of these systems, and how a better understanding would aid sustainability. Understandably, a number of people raised issues with the ways in which we currently survey these systems, with the most informative methods involving removal of the thylakoid membranes from the cell, which can arguably give inaccurate information on such dynamic systems. This is understandably an issue with current methods, as very few techniques currently exist in order to observe the thylakoids in situ. Methods employed by our labs arguably show the most native structures of these thylakoid membranes by using atomic force microscopy (AFM) to ‘feel’ the membrane, as opposed to other imaging methods, which damage the sample to a greater degree, and involve sample preparations which could drastically change the architecture of the membranes.

Thus, AFM and derived methods such as affinity AFM seem to be the most appropriate way to continue research on the thylakoid membrane, ultimately helping us to better understand the important processes it hosts.