Poster: Protein Targeting & Vesicular Trafficking
Abs #
1182: Function of N- and C-terminal propeptides in vesicular transport of horseradish C1a peroxidase
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Presenter: |
matsui, takeshi , t-matsui@bs.aist-nara.ac.jp |
Authors | matsui, takeshi (A) nakayama, hideki (A) yoshida, kazuya (A) shinmyo, atsuhiko (A) | | Affiliations: |
(A): Nara Institute of Science and Technology
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Peroxidases (PRX, EC 1.11.1.7) are widely distributed across microorganisms, plants, and animals. These enzymes catalyze the oxidation of certain substrates, and at the same time the reduction of hydrogen peroxide to water. In particular, horseradish (Armoracia rusticana) root represents the main source of commercial PRX production. The C isozyme of horseradish peroxidase (HRP C) is used as a reporter enzyme in enzyme immunoassays, diagnostic assays, and histochemistry assays. Genomic DNAs and cDNAs of HRP C and other isozymes have been cloned. It has been reported that the growth-rate was stimulated by overexpression of the prxC1a gene in tobacco and hybrid aspen.
The amino acid sequence deduced from prxC1a cDNA contained the same sequence as that determined from purified HRP C isozyme, and revealed that HRP C is initially synthesized as a preprotein containing propeptides at its N- and C-termini. Both the N-terminal propeptide (NTPP, 30 amino acids) and the C-terminal propeptide (CTPP, 15 amino acids) are excised during protein maturation. We investigated the functional role of HRP C1a NTPP and CTPP in the determination of the vesicular transport route, with using analytic system of transgenic cultured tobacco cells (Nicotiana tabacum, BY2)(1).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 was shunted into the secretory pathway.
1. Matsui et al., Vesicular transport route of horseradish C1a peroxidase is regulated by N- and C-terminal propeptides in tobacco cells Appl. Microbiol. Biotechnol. in press (2003).
