How Are Plants Constructed? — Chromatography Explores

Plants are an amazing part of life on Earth — even David Attenborough made a whole series on them. But, they still hold many mysteries from us. Knowing more about how plants function and grow could become essential as we look a future of warmer climates and an increasing population that probably becomes even more reliant on plants for food, fuel and shelter.

A recent paper published in Nature Plants — The scaffold proteins of lignin biosynthetic cytochrome P450 enzymes — reports on how a team from the Brookhaven National Laboratory and Stony Brook University have looked at one of the fundamental issues regarding our knowledge of plants. How do they grow tall and strong?

Lignin — polymer of the world

Lignin is a cross-linked polymer that is found in plants and algae. It performs a structural role in plants and is one of the main components in cell walls, especially in wood and bark from trees as it can form rigid structures. Lignin is composed of different phenolic groups that are cross-linked together, these individual groups are known as lignols. The main lignols are: 4-hydroxy-3-methoxyphenylpropane, 3,5-dimethoxy-4-hydroxyphenylpropane, and 4-hydroxyphenylpropane. The lignols are found in different concentrations in different types of tree.

In cell walls, lignin is found in the space between cellulose and hemicellulose. It is in part the bonds lignin forms with cellulose and hemicellulose that gives a plant the mechanical strength to support itself as it grows tall. It plays a part in the transport of water in stems — lignin is more hydrophobic than other cell wall components and thus stops the absorption of the water allowing it to flow throughout the plant.

Building blocks of lignin

The team from New York were interested in looking at how enzymes work to act as a scaffold allowing lignols to build a lignin structure — how they help to channel carbon into the cell wall structure. The enzymes establish the structure of the building blocks of lignin. Previously, it was thought that the enzymes worked together and served as sites to arrange the lignol synthesis.

But the work showed that the enzymes don’t interact directly with each other, instead two different proteins embedded in the endoplasmic reticulum interact with the three enzymes. In a press release from Brookhaven, Liu one of the paper’s authors said:

‘These membrane-bound proteins serve as a scaffold to organize and stabilize the three enzymes into a type of molecular machinery that controls the metabolic pathway channeling carbon specifically into building lignin precursors.’

Chromatography was used to analyse the proteins associated with the enzymes. Using chromatography to extract plant components is discussed in the article, A Systematic Approach to Developing Terpene Extraction Conditions Utilising Supercritical Carbon Dioxide. Understanding the processes needed to help plants grow could be the first step in helping humans control plant life in the future.