title: Membrane topology of the electrogenic aspartate-alanine antiporter AspT of Tetragenococcus halophilus.
abstract: AspT is an electrogenic aspartate:alanine exchange protein that represents the vectorial component of a proton-motive metabolic cycle found in some strains of Tetragenococcus halophilus. AspT is the sole member of a new family, the Aspartate: Alanine Exchanger (AAE) family, in secondary transporters, according to the computational classification proposed by Saier et al. (http://www.biology.ucsd.edu/~msaier/transport/). We analyzed the topology of AspT biochemically, by using fusion methods in combination with alkaline phosphatase or beta-lactamase. These results suggested that AspT has a unique topology; 8 TMS, a large cytoplasmic loop (183 amino acids) between TMS5 and TMS6, and N- and C-termini that both face the periplasm. These results demonstrated a unique 2D-structure of AspT as the novel AAE family.
authors.affiliation: Laboratory of Enzymology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Nanatani
authors.forename: Fumito
authors.initials: F
authors.lastname: Ohonishi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoneyama
authors.forename: Tasuku
authors.initials: T
authors.lastname: Nakajima
authors.forename: Keietsu
authors.initials: K
authors.lastname: Abe
mesh_terms: D000595:Amino Acid Sequence; D017920:Antiporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism*; D016983:Enterococcus / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D017920:Antiporters; D011993:Recombinant Fusion Proteins