Repellent signaling by Slit requires the leucine-rich repeats.
Slit is a repellent axon guidance cue produced by the midline glia in Drosophila that is required to regulate the formation of contralateral projections and the lateral position of longitudinal tracts. Four sequence motifs comprise the structure of Slit: a leucine-rich repeat (LRR), epidermal growth factor-like (EGF) repeats, a laminin-like globular (G)-domain, and a cysteine domain. Here we demonstrate that the LRR is required for repellent signaling and in vitro binding to Robo. Repellent signaling by slit is reduced by point mutations that encode single amino acid changes in the LRR domain. By contrast to the EGF or G-domains, the LRR domain is required in transgenes to affect axon guidance. Finally, we show that the midline repellent receptor, Robo, binds Slit proteins with internal deletions that also retain repellent activity. However, Robo does not bind Slit protein missing the LRR. Taken together, our data demonstrate that Robo binding and repellent signaling by Slit require the LRR region.
Battye
R
R
Department of Biology, McMaster University, Hamilton Ontario, L8S 4K1 Canada.
Stevens
A
A
Perry
R L
RL
Jacobs
J R
JR
D000483:Alleles; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000294:innervation; D015870:Gene Expression; D007150:Immunohistochemistry; D007814:Larva; D007930:Leucine / Q000235:genetics*; D009132:Muscles / Q000196:embryology / Q000294:innervation; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D010641:Phenotype; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013329:Structure-Activity Relationship; D019076:Transgenes; D000097905:Roundabout Proteins
D029721:Drosophila Proteins; D007930:Leucine; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C066819:sli protein, Drosophila