Characterization of capsaicin synthase and identification of its gene (csy1) for pungency factor capsaicin in pepper (Capsicum sp.)
- B. C. Narasimha Prasad,
- Vinod Kumar,
- H. B. Gururaj,
- R. Parimalan,
- P. Giridhar, and
- G. A. Ravishankar*
- Plant Cell Biotechnology Department, Central Food Technological Research Institute (Constituent Laboratory of Council of Scientific and Industrial Research), Mysore 570020, India
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Communicated by M. S. Swaminathan, Centre for Research on Sustainable Agricultural and Rural Development, Madras, India, July 17, 2006 (received for review June 20, 2006)
Abstract
Capsaicin is a unique alkaloid of the plant kingdom restricted to the genus Capsicum. Capsaicin is the pungency factor, a bioactive molecule of food and of medicinal importance. Capsaicin is useful as a counterirritant, antiarthritic, analgesic, antioxidant, and anticancer agent. Capsaicin biosynthesis involves condensation of vanillylamine and 8-methyl nonenoic acid, brought about by capsaicin synthase (CS). We found that CS activity correlated with genotype-specific capsaicin levels. We purified and characterized CS (≈35 kDa). Immunolocalization studies confirmed that CS is specifically localized to the placental tissues of Capsicum fruits. Western blot analysis revealed concomitant enhancement of CS levels and capsaicin accumulation during fruit development. We determined the N-terminal amino acid sequence of purified CS, cloned the CS gene (csy1) and sequenced full-length cDNA (981 bp). The deduced amino acid sequence of CS from full-length cDNA was 38 kDa. Functionality of csy1 through heterologous expression in recombinant Escherichia coli was also demonstrated. Here we report the gene responsible for capsaicin biosynthesis, which is unique to Capsicum spp. With this information on the CS gene, speculation on the gene for pungency is unequivocally resolved. Our findings have implications in the regulation of capsaicin levels in Capsicum genotypes.
Footnotes
- *To whom correspondence should be addressed. E-mail: pcbt{at}cftri.res.in
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Author contributions: B.C.N.P., V.K., H.B.G., P.G., and G.A.R. designed research; B.C.N.P., V.K., H.B.G., R.P., P.G., and G.A.R. performed research; B.C.N.P., H.B.G., R.P., and G.A.R. analyzed data; and B.C.N.P. and G.A.R. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. DQ349223 (C. annuum, full-length cDNA), DQ349224 (C. frutescens, full-length cDNA), DQ349225 (C. annuum genomic DNA), and DQ349226 (C. frutescens genomic DNA)].
- Abbreviation:
- CS,
- capsaicin synthase.
- © 2006 by The National Academy of Sciences of the USA
