title: Rab-subfamily-specific regions of Ypt7p are structurally different from other RabGTPases.
abstract: The GTPase Ypt7p from S. cerevisiae is involved in late endosome-to-vacuole transport and homotypic vacuole fusion. We present crystal structures of the GDP- and GppNHp-bound conformation of Ypt7p solved at 1.35 and 1.6 A resolution, respectively. Despite the similarity of the overall structure to other Ypt/Rab proteins, Ypt7p displays small but significant differences. The Ypt7p-specific residues Tyr33 and Tyr37 cause a difference in the main chain trace of the RabSF2 region and form a characteristic surface epitope. Ypt7p*GppNHp does not display the helix alpha2, characteristic of the Ras-superfamily, but instead possess an extended loop L4/L5. Due to insertions in loops L3 and L7, the neighboring RabSF1 and RabSF4 regions are different in their conformations to those of other Ypt/Rab proteins.
authors.affiliation: Abteilung für Physikalische Biochemie, Max-Planck Institut für Molekulare Physiologie, Otto-Hahn Strasse 11, 44227 Dortmund, Germany.
authors.forename: Alexandru-Tudor
authors.initials: AT
authors.lastname: Constantinescu
authors.forename: Alexey
authors.initials: A
authors.lastname: Rak
authors.forename: Kirill
authors.initials: K
authors.lastname: Alexandrov
authors.forename: Heike
authors.initials: H
authors.lastname: Esters
authors.forename: Roger S
authors.initials: RS
authors.lastname: Goody
authors.forename: Axel J
authors.initials: AJ
authors.lastname: Scheidig
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006153:Guanosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D020691:rab GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D006153:Guanosine Diphosphate; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins