Spastin and atlastin, two proteins mutated in autosomal-dominant hereditary spastic paraplegia, are binding partners.
The pure hereditary spastic paraplegias (HSPs) are a group of conditions in which there is a progressive length-dependent degeneration of the distal ends of the corticospinal tract axons, resulting in spastic paralysis of the legs. Pure HSPs are most frequently inherited in an autosomal-dominant pattern and are commonly caused by mutations either in the SPG4 gene spastin or in the SPG3A gene atlastin. To identify binding partners for spastin, we carried out a yeast two-hybrid screen on a brain cDNA library, using spastin as bait. Remarkably, nearly all of the positive interacting prey clones coded for atlastin. We have verified the physiological relevance of this interaction using co-immunoprecipitation, glutathione S-transferase pull-down and intracellular co-localization experiments. We show that the spastin domain required for binding to atlastin lies within the N-terminal 80 residues of the protein, a region that is only present in the predominantly cytoplasmic, full-length spastin isoform. These data suggest that spastin and atlastin function in the same biochemical pathway and that it is the cytoplasmic function of spastin which is important for the pathogenesis of HSP. They also provide further evidence for a physiological and pathological role of spastin in membrane dynamics.
Sanderson
Christopher M
CM
The Psychological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
Connell
James W
JW
Edwards
Thomas L
TL
Bright
Nicholas A
NA
Duley
Simon
S
Thompson
Amanda
A
Luzio
J Paul
JP
Reid
Evan
E
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D015723:Gene Library; D005982:Glutathione Transferase; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding; D015419:Spastic Paraplegia, Hereditary / Q000235:genetics*; D000074181:Spastin; D020798:Two-Hybrid System Techniques; D015003:Yeasts
D008565:Membrane Proteins; D005982:Glutathione Transferase; C440006:ATL1 protein, human; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D000074181:Spastin; C400283:SPAST protein, human