title: Identification of a gain-of-function mutation in a Golgi P-type ATPase that enhances Mn2+ efflux and protects against toxicity.
abstract: P-type ATPases transport a wide array of ions, regulate diverse cellular processes, and are implicated in a number of human diseases. However, mechanisms that increase ion transport by these ubiquitous proteins are not known. SPCA1 is a P-type pump that transports Mn(2+) from the cytosol into the Golgi. We developed an intra-Golgi Mn(2+) sensor and used it to screen for mutations introduced in SPCA1, on the basis of its predicted structure, which could increase its Mn(2+) pumping activity. Remarkably, a point mutation (Q747A) predicted to increase the size of its ion permeation cavity enhanced the sensor response and a compensatory mutation restoring the cavity to its original size abolished this effect. In vivo and in vitro Mn(2+) transport assays confirmed the hyperactivity of SPCA1-Q747A. Furthermore, increasing Golgi Mn(2+) transport by expression of SPCA1-Q747A increased cell viability upon Mn(2+) exposure, supporting the therapeutic potential of increased Mn(2+) uptake by the Golgi in the management of Mn(2+)-induced neurotoxicity.
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
authors.forename: Somshuvra
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Adam D
authors.initials: AD
authors.lastname: Linstedt
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000409:Alanine / Q000737:chemistry; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D010766:Phosphorylation; D017354:Point Mutation; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D033921:Vesicular Transport Proteins / Q000737:chemistry
chemical_list: C107340:GOLIM4 protein, human; D033921:Vesicular Transport Proteins; D008345:Manganese; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; C403624:ATP2C1 protein, human; D000252:Calcium-Transporting ATPases; D000409:Alanine