title: The twisted relation between Pnu and SWEET transporters.
abstract: The evolutionary relation between sugar and vitamin transporters from the SWEET and Pnu families is unclear. They have similar 3D structures, but differ in the topology of their secondary structure elements, and lack significant sequence similarity. Here we analyze the structures and sequences of different members of the SWEET and Pnu transporter families and propose an evolutionary pathway by which they may have diverged from a common ancestor. A 3D domain swapping event can explain the topological differences between the families, as well as the puzzling observation that a highly conserved and essential sequence motif of the SWEET family (the PQ loop) is absent from the Pnu transporters.
authors.affiliation: University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands.
authors.forename: Michael
authors.initials: M
authors.lastname: Jaehme
authors.affiliation: University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Guskov
authors.affiliation: University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands. Electronic address: d.j.slotboom@rug.nl.
authors.forename: Dirk Jan
authors.initials: DJ
authors.lastname: Slotboom
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D001692:Biological Transport; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family / Q000235:genetics / Q000502:physiology; D017433:Protein Structure, Secondary
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins
keywords: Pnu; SWEET; membrane transporter; membrane transporter fold; protein evolution; protein topology