title: Structure of astrotactin-2: a conserved vertebrate-specific and perforin-like membrane protein involved in neuronal development.
abstract: The vertebrate-specific proteins astrotactin-1 and 2 (ASTN-1 and ASTN-2) are integral membrane perforin-like proteins known to play critical roles in neurodevelopment, while ASTN-2 has been linked to the planar cell polarity pathway in hair cells. Genetic variations associated with them are linked to a variety of neurodevelopmental disorders and other neurological pathologies, including an advanced onset of Alzheimer's disease. Here we present the structure of the majority endosomal region of ASTN-2, showing it to consist of a unique combination of polypeptide folds: a perforin-like domain, a minimal epidermal growth factor-like module, a unique form of fibronectin type III domain and an annexin-like domain. The perforin-like domain differs from that of other members of the membrane attack complex-perforin (MACPF) protein family in ways that suggest ASTN-2 does not form pores. Structural and biophysical data show that ASTN-2 (but not ASTN-1) binds inositol triphosphates, suggesting a mechanism for membrane recognition or secondary messenger regulation of its activity. The annexin-like domain is closest in fold to repeat three of human annexin V and similarly binds calcium, and yet shares no sequence homology with it. Overall, our structure provides the first atomic-resolution description of a MACPF protein involved in development, while highlighting distinctive features of ASTN-2 responsible for its activity.
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Tao
authors.initials: T
authors.lastname: Ni
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Karl
authors.initials: K
authors.lastname: Harlos
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK gilbert@strubi.ox.ac.uk.
authors.forename: Robert
authors.initials: R
authors.lastname: Gilbert
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D055495:Neurogenesis; D010802:Phylogeny; D011485:Protein Binding; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014714:Vertebrates / Q000235:genetics / Q000378:metabolism*
chemical_list: C000593289:ASTN2 protein, human; D006023:Glycoproteins; D007295:Inositol Phosphates; D009419:Nerve Tissue Proteins; C516441:inositol trispyrophosphate
keywords: X-ray crystallography; astrotactin-2; biophysical interaction analysis; membrane attack complex-perforin protein; neural migration control