A high affinity RIM-binding protein/Aplip1 interaction prevents the formation of ectopic axonal active zones.
Synaptic vesicles (SVs) fuse at active zones (AZs) covered by a protein scaffold, at Drosophila synapses comprised of ELKS family member Bruchpilot (BRP) and RIM-binding protein (RBP). We here demonstrate axonal co-transport of BRP and RBP using intravital live imaging, with both proteins co-accumulating in axonal aggregates of several transport mutants. RBP, via its C-terminal Src-homology 3 (SH3) domains, binds Aplip1/JIP1, a transport adaptor involved in kinesin-dependent SV transport. We show in atomic detail that RBP C-terminal SH3 domains bind a proline-rich (PxxP) motif of Aplip1/JIP1 with submicromolar affinity. Pointmutating this PxxP motif provoked formation of ectopic AZ-like structures at axonal membranes. Direct interactions between AZ proteins and transport adaptors seem to provide complex avidity and shield synaptic interaction surfaces of pre-assembled scaffold protein transport complexes, thus, favouring physiological synaptic AZ assembly over premature assembly at axonal membranes.
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Matthias
http://orcid.org/0000-0002-1739-5825
M
Siebert
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Mathias A
http://orcid.org/0000-0002-0947-9172
MA
Böhme
Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.
Jan H
JH
Driller
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Husam
H
Babikir
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Malou M
MM
Mampell
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Ulises
U
Rey
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Niraja
http://orcid.org/0000-0002-2867-7131
N
Ramesh
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Tanja
T
Matkovic
Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.
Nicole
N
Holton
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Suneel
S
Reddy-Alla
Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Fabian
F
Göttfert
Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Dirk
D
Kamin
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Christine
C
Quentin
Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States.
Susan
S
Klinedinst
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Till Fm
http://orcid.org/0000-0002-2917-5889
TF
Andlauer
Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Stefan W
SW
Hell
Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States.
Catherine A
CA
Collins
Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.
Markus C
MC
Wahl
Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany.
Bernhard
http://orcid.org/0000-0001-7928-4488
B
Loll
Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany.
Stephan J
SJ
Sigrist
D000818:Animals; D001370:Axonal Transport; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D061848:Optical Imaging; D011485:Protein Binding; D025941:Protein Interaction Mapping; D021381:Protein Transport; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism*
C524132:APP-like protein interacting protein 1, Drosophila; D002352:Carrier Proteins; D029721:Drosophila Proteins; C577877:RIM protein, Drosophila; D020692:rab3 GTP-Binding Proteins
AZ scaffold proteins; D. melanogaster; active zone; axonal transport; neuroscience; synapses; transport adaptor