Splice form dependence of beta-neurexin/neuroligin binding interactions.
Alternatively spliced beta-neurexins (beta-NRXs) and neuroligins (NLs) are thought to have distinct extracellular binding affinities, potentially providing a beta-NRX/NL synaptic recognition code. We utilized surface plasmon resonance to measure binding affinities between all combinations of alternatively spliced beta-NRX 1-3 and NL 1-3 ectodomains. Binding was observed for all beta-NRX/NL pairs. The presence of the NL1 B splice insertion lowers beta-NRX binding affinity by approximately 2-fold, while beta-NRX splice insertion 4 has small effects that do not synergize with NL splicing. New structures of glycosylated beta-NRXs 1 and 2 containing splice insertion 4 reveal that the insertion forms a new beta strand that replaces the beta10 strand, leaving the NL binding site intact. This helps to explain the limited effect of splice insert 4 on NRX/NL binding affinities. These results provide new structural insights and quantitative binding information to help determine whether and how splice isoform choice plays a role in beta-NRX/NL-mediated synaptic recognition.
Koehnke
Jesko
J
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
Katsamba
Phinikoula S
PS
Ahlsen
Goran
G
Bahna
Fabiana
F
Vendome
Jeremie
J
Honig
Barry
B
Shapiro
Lawrence
L
Jin
Xiangshu
X
D017398:Alternative Splicing / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D055592:Biophysical Phenomena; D002118:Calcium / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D018360:Crystallography, X-Ray / Q000379:methods; D006031:Glycosylation; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D020890:Neuregulin-1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D020033:Protein Isoforms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020349:Surface Plasmon Resonance / Q000379:methods; D014162:Transfection; D014461:Ultracentrifugation / Q000379:methods
D015816:Cell Adhesion Molecules, Neuronal; D020890:Neuregulin-1; D020033:Protein Isoforms; C117467:neuregulin beta; C093438:neuroligin 1; D002118:Calcium