Molecular basis of synaptic specificity by immunoglobulin superfamily receptors in Drosophila

Elife. 2019 Jan 28:8:e41028. doi: 10.7554/eLife.41028.

Abstract

In stereotyped neuronal networks, synaptic connectivity is dictated by cell surface proteins, which assign unique identities to neurons, and physically mediate axon guidance and synapse targeting. We recently identified two groups of immunoglobulin superfamily proteins in Drosophila, Dprs and DIPs, as strong candidates for synapse targeting functions. Here, we uncover the molecular basis of specificity in Dpr-DIP mediated cellular adhesions and neuronal connectivity. First, we present five crystal structures of Dpr-DIP and DIP-DIP complexes, highlighting the evolutionary and structural origins of diversification in Dpr and DIP proteins and their interactions. We further show that structures can be used to rationally engineer receptors with novel specificities or modified affinities, which can be used to study specific circuits that require Dpr-DIP interactions to help establish connectivity. We investigate one pair, engineered Dpr10 and DIP-α, for function in the neuromuscular circuit in flies, and reveal roles for homophilic and heterophilic binding in wiring.

Keywords: D. melanogaster; cell surface receptors; crystal structure; immunoglobulin superfamily; molecular biophysics; neuromuscular system; neuroscience; protein engineering; structural biology; synapse specificity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Conserved Sequence
  • Crystallography, X-Ray
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / metabolism*
  • Immunoglobulins / chemistry
  • Immunoglobulins / metabolism*
  • Phylogeny
  • Protein Binding
  • Protein Multimerization
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / metabolism*
  • Structural Homology, Protein
  • Synapses / metabolism*

Substances

  • Drosophila Proteins
  • Immunoglobulins
  • Receptors, Cell Surface