Engineering and structure of transient ionotropic glutamate receptor complexes

All aspects of brain function rely on the interplay between networks of functionally related neuronal cells.

These cells are connected by synapses, which are specialized cellular compartments dedicated to rapid electrical and chemical signalling.

Excitatory neurotransmission in the vertebrate central nervous system (CNS) is largely mediated by the ionotropic glutamate receptors (iGluRs).

These postsynaptic receptors conduct cations into the cell in response to binding of the neurotransmitter glutamate released from presynaptic vesicles. Accumulation and positioning of iGluRs at neuronal synapses are crucial for enabling correct neurotransmission.

While it is known that extracellular scaffolding proteins (ESPs) interact with iGluRs to stabilize these receptors at synapses, the transient, low-affinity nature of these protein interactions has so far precluded complex structure determination and therefore a precise mechanistic understanding of their function.

The aim of this proposal is to implement state-of-the-art techniques of protein engineering to stabilise iGluR:ESP interactions for structure determination by affinity maturation of their interaction interfaces.

I will focus on two well-established complexes: Cerebellin-Glutamate receptor Delta (Cbln-GluD) and Neuronal Pentraxin-AMPA receptor (NP-AMPAR).

Structural insights into the full-length synapse-spanning Cbln-GluD and NP-AMPAR interactions will elucidate how clustering and trans-synaptic anchoring of iGluRs contribute to synaptic transmission, as well as pave the way for the design of engineered synaptic organizer proteins capable of remodelling synapses.

During this project I will gain experience in protein engineering which will allow me to establish a career as an independent scientist with a focus on tackling complex structural biology problems with translational applications.