Large alkyl side-chains of isoleucine and leucine in the NPIRL region constitute the core of the vacuolar sorting determinant of sporamin precursor.
The N-terminal propeptide of the sporamin precursor contains vacuolar targeting information within the Asn-26/Pro-27/Ile-28/Arg-29/Leu-30 (NPIRL) sequence. An Agrobacterium-mediated transient expression assay with tobacco BY-2 cells was employed to investigate the role of each amino acid of the NPIRL region in vacuolar targeting. Replacement of Asn-26, Pro-27, Ile-28 and Leu-30 with several amino acids caused secretion of the mutant prosporamin. Leu was the only amino acid that could be substituted for Ile-28 without affecting transport. Exchange of Leu-30 for amino acids with small side-chains abolished vacuolar delivery. These results indicate that the consensus composition of the NPIRL sequence is [preferably Asn]-[not acidic]-[Ile or Leu]-[any amino acid]-[large and hydrophobic] and suggest that the large alkyl side-chains of Ile-28 and Leu-30 constitute the core of the vacuolar sorting determinant.
Matsuoka
K
K
Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Nakamura
K
K
D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000254:growth & development; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001692:Biological Transport; D002478:Cells, Cultured; D006868:Hydrolysis; D007532:Isoleucine / Q000737:chemistry*; D007930:Leucine / Q000737:chemistry*; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D010947:Plants, Toxic; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000378:metabolism; D013329:Structure-Activity Relationship; D014026:Nicotiana / Q000166:cytology / Q000382:microbiology; D014170:Transformation, Genetic; D014617:Vacuoles / Q000378:metabolism*
D010940:Plant Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; C067142:sporamin protein, Ipomoea batatas; D007532:Isoleucine; D007930:Leucine