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Letter

Proteome Analysis of Pitcher Fluid of the Carnivorous Plant Nepenthes alata

Supporting Info

Naoya Hatano^†^‡ and Tatsuro Hamada*^§

Harima Institute at Spring-8, RIKEN, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan, and Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi-machi, Ishikawa-gun, Ishikawa 921-8836, Japan

Proteome Res., 2008, 7 (2), pp 809–816

DOI: 10.1021/pr700566d

Publication Date (Web): January 10, 2008

†

Harima Institute at Spring-8, RIKEN.

‡

Present address: Rare Sugar Research Center, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.

* To whom correspondence should be addressed: Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi-machi, Ishikawa 921-8836, Japan. Telephone: +81-76-227-7507 . Fax: +81-76-227-7557. E-mail: hamada@ishikawa-pu.ac.jp.

Ishikawa Prefectural University.

Abstract

The genus Nepenthes comprises carnivorous plants that digest insects in pitcher fluid to supplement their nitrogen uptake. In a recent study, two acid proteinases (nepenthesins I and II) were purified from the pitcher fluid. However, no other enzymes involved in prey digestion have been identified, although several enzyme activities have been reported. To identify all the proteins involved, we performed a proteomic analysis of Nepenthes pitcher fluid. The secreted proteins in pitcher fluid were separated by sodium dodecyl sulfate−polyacrylamide gel electrophoresis, and several protein bands were detected by silver staining. The proteins were identified by in-gel tryptic digestion, de novo peptide sequencing, and homology searches against public databases. The proteins included homologues of β- d-xylosidase, β-1,3-glucanase, chitinase, and thaumatin-like protein, most of which are designated “pathogenesis-related proteins”. These proteins presumably inhibit bacterial growth in the pitcher fluid to ensure sufficient nutrients for Nepenthes growth.

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