title: The crystal structure of saporin SO6 from Saponaria officinalis and its interaction with the ribosome.
abstract: The 2.0 A resolution crystal structure of the ribosome inactivating protein saporin (isoform 6) from seeds of Saponaria officinalis is presented. The fold typical of other plant toxins is conserved, despite some differences in the loop regions. The loop between strands beta7 and beta8 in the C-terminal region which spans over the active site cleft appears shorter in saporin, suggesting an easier access to the substrate. Furthermore we investigated the molecular interaction between saporin and the yeast ribosome by differential chemical modifications. A contact surface inside the C-terminal region of saporin has been identified. Structural comparison between saporin and other ribosome inactivating proteins reveals that this region is conserved and represents a peculiar motif involved in ribosome recognition.
authors.affiliation: Department of Biochemical Sciences and CNR Centre for Molecular Biology, University of Rome 'La Sapienza', Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Savino
authors.forename: L
authors.initials: L
authors.lastname: Federici
authors.forename: R
authors.initials: R
authors.lastname: Ippoliti
authors.forename: E
authors.initials: E
authors.lastname: Lendaro
authors.forename: D
authors.initials: D
authors.lastname: Tsernoglou
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D000922:Immunotoxins; D008239:Lysine / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D010944:Plants / Q000737:chemistry*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D054789:Ribosome Inactivating Proteins, Type 1; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D000076985:Saporins; D012639:Seeds / Q000737:chemistry; D016415:Sequence Alignment; D013387:Succinic Anhydrides / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D015003:Yeasts / Q000166:cytology
chemical_list: D000922:Immunotoxins; D010446:Peptide Fragments; D010940:Plant Proteins; D020033:Protein Isoforms; D054789:Ribosome Inactivating Proteins, Type 1; D013387:Succinic Anhydrides; C031801:succinic anhydride; D009699:N-Glycosyl Hydrolases; D000076985:Saporins; D014357:Trypsin; D008239:Lysine