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September 5, 2006
Source:
Proceedings of the National
Academies of Sciences (PNAS)
September 5, 2006 | vol. 103 | no. 36 | 13315-13320
http://www.pnas.org/cgi/content/abstract/103/36/13315?etoc
- 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
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.
Source:
http://www.pnas.org/cgi/content/abstract/103/36/13315?etoc
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