title: Targeting of proConA to the plant vacuole depends on its nine amino-acid C-terminal propeptide.
abstract: Concanavalin A (ConA) is a well characterized and extensively used lectin accumulated in the protein bodies of jack bean cotyledons. ConA is synthesized as an inactive precursor proConA. The maturation of inactive proConA into biologically active ConA is a complex process including the removal of an internal glycopeptide and a C-terminal propeptide (CTPP), followed by a head-to-tail ligation of the two largest polypeptides. The cDNA encoding proConA was cloned and expressed in tobacco BY-2 cells. ProConA was slowly transported to the vacuole where its maturation into ConA was similar to that in jack bean cotyledons, apart from an incomplete final ligation. To investigate the role of the nine amino acid CTPP, a truncated form lacking the propeptide (proConADelta9) was expressed in BY-2 cells. In contrast to proConA, proConADelta9 was rapidly chased out of the endoplasmic reticulum (ER) and secreted into the culture medium. The CTPP was then fused to the C-terminal end of a secreted form of green fluorescent protein (secGFP). When expressed in tobacco BY-2 cells and leaf protoplasts, the chimaeric protein was located in the vacuole whereas secGFP was located in the culture medium and in the vacuole. Altogether, our results show we have isolated a new C-terminal vacuolar sorting determinant.
authors.affiliation: CNRS UMR 6037, IFRMP 23, GDR 2590, Université de Rouen, UFR des Sciences, Bâtiment Extension Biologie, Mont-Saint-Aignan, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Saint-Jore-Dupas
authors.forename: Saint-Jore-Dupas
authors.initials: SJ
authors.lastname: Claude
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Gilbert
authors.forename: Gilbert
authors.initials: G
authors.lastname: Marie-Agnès
authors.forename: Catalina
authors.initials: C
authors.lastname: Ramis
authors.forename: Ramis
authors.initials: R
authors.lastname: Catalina
authors.forename: Nadine
authors.initials: N
authors.lastname: Paris
authors.forename: Paris
authors.initials: P
authors.lastname: Nadine
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Kiefer-Meyer
authors.forename: Kiefer-Meyer
authors.initials: KM
authors.lastname: Marie-Christine
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Neuhaus
authors.forename: Neuhaus
authors.initials: N
authors.lastname: Jean-Marc
authors.forename: Loïc
authors.initials: L
authors.lastname: Faye
authors.forename: Faye
authors.initials: F
authors.lastname: Loïc
authors.forename: Véronique
authors.initials: V
authors.lastname: Gomord
authors.forename: Gomord
authors.initials: G
authors.lastname: Véronique
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D003208:Concanavalin A / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D018076:DNA, Complementary; D016521:Electrophoresis, Gel, Pulsed-Field; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism*; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D009842:Oligopeptides; D011498:Protein Precursors; D003208:Concanavalin A