From Western Cape to Great Western: South African PhD student Cathrine Pfukwa wins award for experiment with ancient antibiotic here at the CLF
10 May 2018
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- Helen Towrie

Only 2 years into her PhD, Cathrine has already made huge strides in this exciting, cutting-edge project, which has particular importance in our current climate where more and more bacteria, funguses and viruses are becoming resistant to antibiotics.

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Amongst the Boland Mountains in the winelands of South Africa sits Stellenbosch University, a campus with an incredible history. Residing in prestigious grounds within a town which hosts a unique mixture of architecture both old and new, the university is home to a community of 29,000 students, including 4,000 foreign students from 100 countries. In addition, there are 3,000 permanent staff members living within the five campuses.

Since its establishment in 1918, Stellenbosch University has offered an impressively wide variety of courses – including, uniquely due to its location, a degree in Winery. Although situated in Western Cape of South Africa, the university has established close ties with the CLF.

Tony Parker, STFC fellow and CLF scientist here in RAL, is a Professor Extraordinaire at Stellenbosch since 2011 – awarded such a title due to his work in supporting the development of lasers in South Africa and his role in supporting the establishment of the LRI (Laser Research Institute) back in 2000. Today, the LRI is recognised as a leader in the laser science community in South Africa and the African continent.  On top of this, Tony also runs the CLF-South Africa Newton Fund, along with David Neely who runs the CLF-China and Rajeev Pattathil who runs CLF-India. The Newton fund is part of BEIS, which fulfils the aim of being a collaborative scientific establishment, working together with other nations.

It was at LRI that Stellenbosch's Cathrine Pfukwa, who completed her Masters degree with her supervisor, Dr. Pieter Neethling and Prof. Erich Rohwer, and learnt the valuable skills needed for conducting her current exciting PhD project– and potentially ground breaking – experiments on a molecule called Gramicidin S here at the CLF.

The main objective for Cathrine's research into Gramicidin S is to establish whether it could be viable for medical use. This is not the first time this has been considered – it actually was being regularly used in drugs up until a few years ago. It ceased to be used when it was found there were problems with how it changes when in contact with liquids. These issues are what Catherine and her team are working towards identifying and fixing.

Only 2 years into her PhD, Cathrine has already made huge strides in this exciting, cutting-edge project, which has particular importance in our current climate where more and more bacteria, funguses and viruses are becoming resistant to antibiotics.

Before delving into the details of the experiment, it may be helpful to give an overview of the 'wonder molecule' itself. Gramicidin S is one of the world's most ancient antibiotics and can be found naturally in many soils. The interesting thing about the chemical properties of GS is that it is not only an antibiotic, but an antifungal. These anti-fungal properties can break down biofilms, such as those which form around verrucae and which make them stubborn against treatment, and this is what renders the molecule different from other Gramicidins currently used in pharmaceuticals. GS is also unique in that it has a circular molecular structure rather than a linear one, which, among other things, makes it hydrophobic.

In collaboration with her PhD supervisors GS expert, Prof Marina Rautenbach (who is one of the only people in the world who can source GS), and Dr Pieter Neethling, Cathrine aims to pave the way toward pharmaceutical use by analysing detailed SERS images of Gramicidin's molecular structure in various environments. In her recent experiment using Ultra-LIFEtime, she hoped to identify how cross-peak reactions might affect intra-molecular stability.

Since the molecule's structure, a cyclic peptide, is a set of amino acids which are all connected and interact with each other dependent on its molecular structure, Cathrine has been trying to find out how its structure changes in differing environments (for example different solutions) using vibrational spectroscopy, both Raman and infrared spectroscopies.  In fact her stay at the CLF means Cathrine was able to successfully gain access to perform 2-dimensional infrared spectroscopy (2DIR) using the unique capabilities of the Ultra lasers. 2DIR is rather complicated:

“It's like having houses on a street," Tony Parker, Cathrine's CLF supervisor, explained, “These houses and people all currently live in harmony, but what happens if a new house is built? How will this affect the rest of the neighbourhood? Will the new neighbours get along, or which of the neighbours will interact with the new house and its family the most?..."

What this means is that changes in the shape of the GS molecule occurs when it comes into contact with certain liquids. That is in water it can have one structure but in an organic solvent it will have another. These variations in moisture content are believed to influence the way that gramicidin S interacts with its environment, with polar solvents such as water creating completion between its intra-molecular hydrogen bonding, turning more to favour inter-molecular hydrogen bonding. These forces generate different structures and thus the environment is controlling, ultimately, the activity of the peptide.

When the team, working with international expert Prof Neil Hunt (Strathclyde and student Lucy Minn​es), used infrared on Ultra-LIFEtime, which is one of the best 2D IR generators in the world, they got cross-peaks in the molecule. The changes in the spectrum holds clues to a specific structure of GS.

"This work has been fascinating to me because it has enabled me to achieve difficult goals as well pushing me to greater heights in the science research field." Cathrine Pfukwa said about the experiment, “My time at the Research Complex has been a rare opportunity and has provided me with exposure in the available labs such as the LIFEtime lab. Working in the LIFEtime lab has been interesting because this is a lab with state of the art technology which enable scientists to obtain information from fundamental processes which occur in various systems, such as biological systems which I work with."

The CLF is incredibly proud to have been home to such great research, however, that is not where Cathrine's accomplishments end. In November 2017, in recognition of her work, Cathrine was invited to give a talk to over 100 people about her use of vibrational spectroscopy to illustrate the properties of Gramicidin S at African Laser Centre Conference in South Africa. Once the talks were over, she was presented with an award in recognition of her outstanding work!

Cathrine shared her thoughts about the event, “I am very much honoured to have received this award because it has funded my doctorate studies, most importantly I am grateful to my supervisor here at the research complex Prof. A.W. Parker for equipping me with great research skills and for his tremendous support in this journey."

But this has been about more than the experiment and subsequent award; the Newton Experience tries to be a cultural exchange as well as a scientific opportunity. What it does is, on top of offering a research grant, it gives scientists and PhD students the opportunity to travel to countries they may never have experienced before. This enables the opportunity to be submerged in brand new cultures and atmospheres while gaining unique scientific knowledge and making valuable connections. For Cathrine, this experience has helped her gain confidence – so much so that colleagues at Stellenbosch were incredibly impressed by her poise and presence when she gave her talk in South Africa.

Looking forward, Cathrine will be returning to Stellenbosch to complete  her PhD studies and get involved in Student Chapter at Stellenbosch, where she can demonstrate laser capability in South Africa and possibly the world. It is renowned as a tremendous outreach programme, and Cathrine's input in it will be greatly felt.

 

Cathrine's supervisors:

Prof. Marina Rautenbach:

https://www.sun.ac.za/english/faculty/science/biochemistry/research/rautenbach-group

Dr. Pieter Neethling and Prof. Erich Rohwer:

https://www.sun.ac.za/english/faculty/science/physics/people/academic

Prof. Tony Parker: https://www.clf.stfc.ac.uk/Pages/Tony-Parker.aspx

Laser Research Institute

http://www.sun.ac.za/english/faculty/science/physics/lri

African Laser Centre: https://www.csir.co.za/csir-african-laser-centre-provides-support-youth-across-africa-0

 



Contact: Towrie, Helen (STFC,RAL,CLF)