Recognition of C-terminal amino acids in tubulin by pore loops in Spastin is important for microtubule severing.
Spastin, an AAA ATPase mutated in the neurodegenerative disease hereditary spastic paraplegia, severs microtubules. Many other AAA proteins form ring-shaped hexamers and contain pore loops, which project into the ring's central cavity and act as ratchets that pull on target proteins, leading, in some cases, to conformational changes. We show that Spastin assembles into a hexamer and that loops within the central pore recognize C-terminal amino acids of tubulin. Key pore loop amino acids are required for severing, including one altered by a disease-associated mutation. We also show that Spastin contains a second microtubule binding domain that makes a distinct interaction with microtubules and is required for severing. Given that Spastin engages the MT in two places and that both interactions are required for severing, we propose that severing occurs by forces exerted on the C-terminal tail of tubulin, which results in a conformational change in tubulin, which releases it from the polymer.
White
Susan Roehl
SR
Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Evans
Katia J
KJ
Lary
Jeffrey
J
Cole
James L
JL
Lauring
Brett
B
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000473:pathology; D019556:COS Cells; D002522:Chlorocebus aethiops; D008870:Microtubules / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009434:Neural Pathways / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology; D015419:Spastic Paraplegia, Hereditary / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D000074181:Spastin; D014404:Tubulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014855:Wallerian Degeneration / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology
D000596:Amino Acids; D014404:Tubulin; D000251:Adenosine Triphosphatases; D000074181:Spastin; C400283:SPAST protein, human