Mussawar Ahmad, AMRA
Bacteria are of the most primitive forms of life on the planet. However, even the fundamental tasks of growing and surviving requires the precise orchestration of what is a complex network of chemical reactions. How is this orchestration conducted? How does it enable the cell to adapt and survive?
On 8 August 2020, Dr Ahmad Mannan Sahib, a postdoctoral research associate at the University of Warwick’s Integrative Synthetic Biology Centre and School of Engineering led an AMRA Research Café addressing precisely these questions.
He described some examples of control systems in bacteria, including from his own work, and discussed how the design of those systems encoded in the DNA beautifully solve the problem bacteria face, when adapting to survive in an ever changing environment.
The talk started with a description of a control system, reflecting on a thermostat example to enable the audience of almost 30 to get to grips with the concept of what a control system is.
It then went on to discuss a number of example control systems in bacteria, and how they solve problems at different scales, starting at the molecular level, then cellular level and then at the level of the population and even interspecies.
It was fascinating, not only to gain an insight on how the control system works, but also learn about the control strategies adopted by nature and how their design optimally solved the problem faced.
One of my favourite examples was that of the population level. To ensure long-term survival, bacteria populations need to increase genetic diversity. The question is when should that genetic diversity be increased? Let’s first think about the problem. We all understand that increasing genetic diversity is important for the long-term survival of populations. When there is a drastic change of environment, most of the population may not be able to survive in it, but a subgroup of them with slightly different genetic makeup may be better adapted to survive in the new environment. If the population is all identical and precisely suited to a very specific environment, there is a risk it may not survive a sudden change.
Investing in some genetic diversity is therefore advantageous to ensuring continuity of the species in the long-term. This is however not without some cost. Since not all the population is perfectly suited to the current environment, a sub-population may not grow as well. Too much genetic diversity and growth of the overall population suffers, putting at risk it’s continuity. How is this genetic diversity controlled?
Well, one of the control’s components is a protein molecule called Ada. This protects DNA from damage during a process called methylation. Interestingly, the cells have only one molecule per cell, on average. So, when cells are growing rapidly under the best conditions, some cells may not have any Ada while others do. In turn, this means that some cells will be more susceptible to DNA damage, resulting in more mutations and so greater genetic diversity! So what does this mean? A component of the control system involved in facilitating genetic diversity is in play only when the population is growing fast and can therefore “afford” to diversify and accept unfit members of the population, a beautifully simple and elegant solution to the question of when to invest in diversification.
After describing the designs in nature, Dr Ahmad Mannan Sahib then went on to discuss how these controls can be engineered and repurposed in application for the service of mankind. Examples included bioremediation, where bacteria could be used for pollution control, as well as therapeutic applications with experiments on using engineering bacteria to break down cancer tissue.
However, he then went on to discuss the challenges that need to be addressed in order to meet these visions of application, namely that human-centric objectives oft en oppose those in nature.
To conclude the talk, Dr Ahmad Mannan Sahib suggested that we should learn from nature, distil design principles, and repurpose them for human needs. He also reflected on the following verse from the Holy Quran:
فَاَقِمۡ وَجۡہَکَ لِلدِّیۡنِ حَنِیۡفًا ؕ فِطۡرَتَ اللّٰہِ الَّتِیۡ فَطَرَ النَّاسَ عَلَیۡہَا ؕ لَا تَبۡدِیۡلَ لِخَلۡقِ اللّٰہِ ؕ ذٰلِکَ الدِّیۡنُ الۡقَیِّمُ ٭ۙ وَ لٰکِنَّ اَکۡثَرَ النَّاسِ لَا یَعۡلَمُوۡنَ
“So set thy face to the service of religion as one devoted to God. And follow the nature made by Allah – the nature in which He has created mankind. There is no altering the creation of Allah. That is the right religion. But most men know not.” (Surah al-Rum, Ch.30: V.31)
He commented on his understanding of this verse, in which Allah advises mankind to learn from nature in order to harness it, and not to go against it as there is “no altering the creation of Allah”.
Further, he reflected on the importance of seeking knowledge around creation and nature by referring to, “But most men know not”.
After the talk there was a question and answer session that delivered engaging conversation and may lead to collaborations in the future, insha-Allah.
To listen to the full talk, please visit: www.youtube.com/watch?v=8L37-SoQr9c
The next AMRA Cafe will be held at the end of September and details will be circulated to the AMRA membership.
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