Vesicular transport route of horseradish C1a peroxidase is regulated by N- and C-terminal propeptides in tobacco cells
Peroxidases (PRX, EC 220.127.116.11) are widely distributed across microorganisms, plants, and animals; and, in plants, they have been implicated in a variety of secondary metabolic reactions. In particular, horseradish (Armoracia rusticana) root represents the main source of commercial PRX production. The prxC1a gene, which encodes horseradish PRX (HRP) C, is expressed mainly in the roots and stems of the horseradish plant. HRP C1a protein is shown to be synthesized as a preprotein with both a N-terminal (NTPP) and a C-terminal propeptide (CTPP). These propeptides, which might be responsible for intracellular localization or secretion, are removed before or concomitant with production of the mature protein. We investigated the functional role of HRP C1a NTPP and CTPP in the determination of the vesicular transport route, using an analytical system of transgenically cultured tobacco cells (Nicotiana tabacum, BY2). Here, we report that NTPP and CTPP are necessary and sufficient for accurate localization of mature HRP C1a protein to vacuoles of the vesicular transport system. We also demonstrate that HRP C1a derived from a preprotein lacking CTPP is shunted into the secretory pathway.
KeywordsEnhance Green Fluorescence Protein Vesicular Transport Enhance Green Fluorescence Protein Gene Enhance Green Fluorescence Protein Fluorescence Sporamin
We are grateful to Dr. Kazuhito Fujiyama of Osaka University for useful discussion and for technical advice regarding the IEF experiment. We would also like to thank Dr. Masami Sekine and Dr. Ko Kato of the Nara Institute of Science and Technology for their helpful discussion. This research was supported by a Grant-in-Aid for scientific research from the Ministry of Education, Science and Culture of Japan.
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