Proteinase inhibitor from ginkgo seeds is a member of the plant nonspecific lipid transfer protein gene family.

Full Abstract

A 9-kD proteinase inhibitor was isolated from the seeds of ginkgo (Ginkgo biloba) and purified to homogeneity. This protein was revealed to partial-noncompetitively inhibit the aspartic acid proteinase pepsin and the cysteine proteinase papain (inhibition constant = 10(-5)-10(-4) m). The cDNA of the inhibitor was revealed to contain a 357-bp open reading frame encoding a 119-amino acid protein with a potential signal peptide (27 residues), indicating that this protein is synthesized as a preprotein and secreted outside the cells. Semiquantitative reverse transcription-polymerase chain reaction revealed that this gene expresses only in seeds, not in stems, leaves, and roots, suggesting that the protein is involved in seed development and/or germination. The inhibitor showed about 40% sequence homology with type-I nonspecific lipid transfer protein (nsLTP1) from other plant species. Actually, this inhibitor exerted both lipid transfer activity and lipid-binding activity, while the protein did not show any antifungal and antibacterial activities. Furthermore, the site-directed mutagenesis study using a recombinant ginkgo nsLTP1 revealed that proline (Pro)-79 and phenylalanine-80 are important on phospholipid transfer activity and that Pro-79 and isoleucine-82 are essential for the binding activity toward cis-unsaturated fatty acids. On the other hand, the alpha-helical content of P79A and F80A mutants was significantly lower than that of the wild-type protein. It was noteworthy that the papain-inhibitory activity of P79A and F80A mutants was elevated twice as much as that of the wild-type protein. In summary, we concluded that Pro-79 plays a critical role in both the lipid transfer and binding activities of ginkgo nsLTP1.

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Author information

Author/s: Sawano, Yoriko (Y); Hatano, Ken-ichi (K); Miyakawa, Takuya (T); Komagata, Hideki (H); Miyauchi, Yumiko (Y); Yamazaki, Hiroshi (H); Tanokura, Masaru (M);

Affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Plant physiology (Plant Physiol), published in United States. (Language: eng)

Reference: 2008-Apr; vol 146 (issue 4) : pp 1909-19

Dates: Created 2008/04/08; Completed 2008/08/05;

PMID: 18305212, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Amino Acid Sequence
Antigens, Plant - chemistry; genetics; isolation & purification
Base Sequence
Carrier Proteins - chemistry; genetics; isolation & purification
Circular Dichroism
Cloning, Molecular
DNA Primers
DNA, Complementary

Electrophoresis, Polyacrylamide Gel
Ginkgo biloba - embryology
Kinetics
Molecular Sequence Data
Plant Proteins - chemistry; genetics; isolation & purification
Protease Inhibitors - chemistry; isolation & purification; pharmacology
Seeds - chemistry
Sequence Homology, Amino Acid

Associated Chemicals: Antigens, Plant (0) ; Carrier Proteins (0) ; DNA Primers (0) ; DNA, Complementary (0) ; Plant Proteins (0) ; Protease Inhibitors (0) ; lipid transfer proteins, plant (0)

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