Changes in targeting efficiencies of proteins to plant microbodies caused by amino acid substitutions in the carboxy-terminal tripeptide.
It has been demonstrated that the carboxyl terminus of microbody enzymes functions as a targeting signal to microbodies in higher plants. We have examined an ability of 24 carboxy-terminal amino acid sequences to facilitate the transport of a cytosolic passenger protein, beta-glucuronidase, into microbodies in green cotyledonary cells of transgenic Arabidopsis. Immunoelectron microscopic analysis revealed that carboxy-terminal tripeptide sequences of the form [C/A/S/P]-[K/R]-[I/L/M] function as a microbody-targeting signal, although tripeptides with proline at the first amino acid position and isoleucine at the carboxyl terminus show weak targeting efficiencies. All known microbody enzymes that are synthesized in a form similar in size to the mature molecule, except catalase, contain one of these tripeptide sequences at their carboxyl terminus.
Hayashi
M
M
Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan.
Aoki
M
M
Kondo
M
M
Nishimura
M
M
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D017360:Arabidopsis; D008830:Microbodies / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D030821:Plants, Genetically Modified; D021382:Protein Sorting Signals / Q000737:chemistry / Q000378:metabolism*
D000596:Amino Acids; D010940:Plant Proteins; D021382:Protein Sorting Signals