title: Defining Minimal Binding Regions in Regulator of Presynaptic Morphology 1 (RPM-1) UsingCaenorhabditis elegansNeurons Reveals Differential Signaling Complexes.
abstract: The intracellular signaling protein regulator of presynaptic morphology 1 (RPM-1) is a conserved regulator of synapse formation and axon termination inCaenorhabditis elegansRPM-1 functions in a ubiquitin ligase complex with the F-box protein FSN-1 and functions through the microtubule binding protein RAE-1. Using a structure-function approach and positive selection for transgenicC. elegans, we explored the biochemical relationship between RPM-1, FSN-1, and RAE-1. This led to the identification of two new domains in RPM-1 that are sufficient for binding to FSN-1, called FSN-1 binding domain 2 (FBD2) and FBD3. Furthermore, we map the RAE-1 binding domain to a much smaller region of RPM-1. Point mutations in RPM-1 that reduce binding to RAE-1 did not affect FSN-1 binding, indicating that RPM-1 utilizes different biochemical mechanisms to bind these molecules. Analysis of RPM-1 protein complexes in the neurons ofC. eleganselucidated two further discoveries: FSN-1 binds to RAE-1, and this interaction is not mediated by RPM-1, and RPM-1 binding to FSN-1 and RAE-1 reduces FSN-1·RAE-1 complex formation. These results indicate that RPM-1 uses different mechanisms to recruit FSN-1 and RAE-1 into independent signaling complexes in neurons.
authors.affiliation: From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Baker
authors.affiliation: From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458 bgrill@scripps.edu.
authors.forename: Brock
authors.initials: B
authors.lastname: Grill
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013569:Synapses / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins
keywords: Caenorhabditis elegans (C. elegans); FSN-1; RAE-1; RPM-1; axon; neuron; structure-function; synapse