Disentangling the neuromolecular networks involved in speech and language

As a biochemist/biophysicist working primarily with proteins, I am naturally drawn to the mechanisms of interactions of biological macromolecules. My name is Sylvia Fanucchi, and I am a senior Lecturer in the Protein Structure Function Research Unit (PSFRU) at the University of the Witwatersrand (Wits) in South Africa. I am interested in how things work at the molecular and atomic level, and how the structure of macromolecules leads to their function. This has inspired my research for the past six years which involves disentangling the neuromolecular networks involved in speech and language. With the GCRF START grant, the doors to collecting the detailed structural information we need through studying and obtaining crystal structures, have been opened for groups in Africa like ours. I have had multiple opportunities, thanks to the grant, to send crystals to the UK’s world class national synchrotron, Diamond Light Source (Diamond).

My research appeals so much to me because our ability to speak, to think, to read is fundamental to humankind. Indeed, my research question started with “what defines speech and language?” but has since expanded to include questions about cognition, reading, and a number of disorders associated with these such as Autism, Dyslexia, Epilepsy and Schizophrenia. Dyslexia, for example, occurs in at least one in 10 people world-wide, putting more than 700 million children and adults worldwide at risk of life-long illiteracy and social exclusion.[1].

Globally, it is estimated that one in 160 children has an Autism Spectrum Disorder (ASD), although estimates vary significantly across studies, and between developed[2] and developing countries[3]. In Southern Africa, very little is known about the prevalence ASD and it is understood that many cases go undiagnosed. Because these disorders can be debilitating and impact on the quality of life of those living with these disorders, and because there is currently no known cure, it is of utmost importance that the complex neuromolecular mechanisms that define these disorders be explored and far better understood. It is hoped that through our research more robust forms of therapeutics could be developed.

Piecing together neuromolecular complexes and networks

In my work, I investigate protein-protein and protein-nucleic acid interactions and try to piece together the neuromolecular complexes and networks that form in both space and time to better understand the mechanism of their interaction and how this is associated with language and cognition, as well as how changes in these may lead to certain disorders. I use an array of biochemical and biophysical techniques to achieve this study and the most prominent of these include, fluorescence anisotropy, isothermal titration calorimetry, hydrogen exchange mass spectrometry and single molecule kinetics. These techniques are used to study binding kinetics and thermodynamics as well as the dynamics and motions of molecules and their interactions with each other, such as the interaction between a protein and DNA, or the interaction between two proteins. The work we have done has mostly been conducted at the PSFRU but I also have collaborations with Dr Previn Naicker and Dr Stoyan Stoychev at the CSIR in Pretoria who assist with mass spectroscopy, and Dr Carlos Penedo[4] from the University of St Andrews in Scotland, UK, who assists with single molecule studies.

The promising biophysical studies conducted in this work will benefit greatly from detailed structural information, provided currently through access to Diamond with the GCRF START grant. Knowledge of the structures of macromolecular complexes allows us to fully understand our system at a level of detail that is otherwise unattainable. And this information, in addition to the dynamics/thermodynamics/kinetics data, will enable us to understand the complexity of these networks at atomic resolution. This will foster a deeper understanding of these mechanisms and enable detailed therapeutics to be designed that would help regulate these disorders, particularly if single strong contributing factors could be identified. Crystallography and solving the structures of the individual interacting partners, as well as of the complexes is therefore of fundamental importance in this project.

FOXP2 protein – the “the language gene”

The protein that sparked this investigation is a transcription factor (a protein that regulates the expression of genes) called FOXP2. FOXP2 was dubbed “the language gene” in the early 2000s when a mutation in this gene that severely impeded DNA binding was found to result in a form of verbal dyspraxia in a family of individuals in the UK. Because FOXP2 is a transcription factor, it is located in the nucleus of cells and its role is to bind to the promotor region of certain genes and facilitate/regulate their transcription to mRNA which ultimately results in the translation and thus expression of that particular protein. Therefore, the regulation of transcription (and hence translation) of any protein will have a direct effect on the functioning of that protein. Our focus is thus on transcriptional regulation because it is the process that initiates downstream effects and predicts which genes will be turned on or off and hence, crudely put, controls the way we function.

Over the past three years, this project therefore focused on the mechanism of DNA binding of FOXP2. Through this work we were able to meticulously describe what drives the interaction of the DNA-binding domain with cognate DNA. We identified electrostatic interactions that played a critical role, we studied binding sequences to gain insight into binding specificity and affinity, we outlined how a domain-swapped dimerisation event that is unique to this subfamily of FOX proteins was able to assist in the dynamics of the DNA binding event, and we described the thermodynamic and kinetic events that occur during binding. In essence, by describing how the transcription factor interacted with DNA, we were able to tell which sequences it preferred, which conditions were most favourable for transcription, and how the structure and fold of the protein was necessary for transcription to occur. Knowing this helps us understand what is necessary for certain genes to be turned on or turned off and how we could interfere with this process.

The focus of our work then moved from DNA binding to the complex network of neuromolecular protein-protein interactions and we began to piece together other interacting partners of FOXP2 and how these interactions affected transcriptional regulation. One specific interaction has yielded a very interesting link to Autism that we are currently exploring further. I have established a very fruitful collaboration with Dr Carlos Penedo from the University of St Andrews primarily through a Newton Fellowship from the Royal Society and the single molecule work done through this collaboration has helped to resolve intricate details about these interactions that I am very excited about[5].

Fast and remote access to diffraction and data collection with Diamond and the GCRF START grant

The opportunities to send crystals to Diamond with the assistance of the GCRF START grant have been revolutionary in enabling us to have fast and remote access to diffraction and data collection that would otherwise have been logistically far more difficult to achieve, and therefore far more sparsely accomplished. Unfortunately, up to now, crystallisation in this project has been a challenge and so far, we are yet to achieve the crystals we require. The fact that the proteins we are attempting to crystallise have not yet had their structures solved and published in the Global Protein Data Bank (PDB) attests to the challenge we knew we would face in obtaining good diffraction data. And while we have obtained some crystals successfully, none of the data we have obtained has been worthy of solving the structure. Nevertheless, the fact that we can obtain crystals is promising and I am determined to persevere with this work until we are successful.

My students are all working on aspects of this project. They work on protein-protein interactions, crystallisation and structural biology, biophysics, and biochemistry. I am currently supervising 5 PhD students and 4 MSc students from diverse backgrounds, 8 of whom are females. I also have 2 postdoctoral Fellows – one from Lesotho and one from Kenya – that have worked under me for the past two years.  In 2020, I graduated 2 PhD students and 2 MSc students. The students are given the autonomy to operate equipment, design experiments and analyse their data. Where possible, and covid-19 pandemic permitting, I encourage them to participate in international workshops and to visit other labs to gain experience and exposure.

Riyaadh Mayet is one of the early career MSc Students in my team.

“The GCRF START grant has enabled the African continent to foster development in synchrotron techniques through collaboration with the UK.” she says. “My MSc project deals with the structural biology of DNA-binding by the TBR1 T-box transcription factor implicated in Autism. The grant has enabled me to send my samples to the Diamond Light Source for diffraction, and without it, it would be very difficult if not impossible to obtain such data. It has also taught me how to better collaborate with fellow researchers, as well as given me the opportunity to learn how to diffract crystals to obtain atomic resolution data. Lastly, I have indirectly benefitted through learning about protein crystallography from fellow researchers who have used the START grant.”

Despite the challenges we have encountered with solving structures in this project, I am very grateful for the support received through the GCRF START grant and the support structures put in place – in particular, in bringing together a strong network of South African crystallographers. Knowing that I have this group of colleagues available across the country that forms a support structure is very reassuring. I am confident that the assistance and opportunities offered to me by this grant over the years is going to result in the ultimate success of my crystal structure dreams for this project and I am both grateful and excited for what the future holds.

Commenting on Sylvia’s research project and the access to infrastructure such as the Diamond synchrotron, Head of School of Molecular and Cell Biology (MCB), Prof Marianne J. Cronje, says,

“I am wholly in support of these research endeavours. Dr Sylvia Fanucchi is an incredibly talented researcher and her position within the school’s Protein Structure Function Research Unit strengthens her efforts by providing access to high-end research infrastructure to support her research in the school.”

Addressing disability is referenced in many of the UN’s Sustainable Development Goals (SDGs), namely health, education, economic growth and employment, inequality, accessibility of human settlements, and others.  Read more about the SDGs here.

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[1] https://www.dyslexia-and-literacy.international/wp-content/uploads/2016/04/DI-Duke-Report-final-4-29-14.pdf accessed 20.02.2021

[2] In the USA~10% of school children struggle with dyslexia and ~1 of every 59 school children is diagnosed with ASD (Yuhang Lin et al Int. J. Environ. Res. Public Health 2020, 17, 7140). The number with ASD has increased over the years reflecting both an increase in awareness as well as a potential increase in environmental triggers although the disorder is currently believed to be predominantly genetically determined.

[3] https://www.who.int/news-room/fact-sheets/detail/Autism-spectrum-disorders (accessed 20.02.2021)

[4] https://risweb.st-andrews.ac.uk/portal/en/persons/carlos-penedo(e1903c4a-e36d-4555-9c7e-e604c9873ba0).html

[5] Thulo M, Rabie MA, Pahad N, Donald HL, Blane AA, Perumal CM, Penedo JC, Fanucchi S. Biosci Rep. 2021 Jan 29;41(1):BSR20202128. doi: 10.1042/BSR20202128