Biomedical subjects

Chae Oh Lim

Publications and source records attributed to Chae Oh Lim.

21 records · Page 2Linked to original sources

PubMed2002

Soybean ascorbate peroxidase suppresses Bax-induced apoptosis in yeast by inhibiting oxygen radical generation.

Bax, a mammalian proapoptotic member of the Bcl-2 family, can induce cell death when expressed in yeast or plant cells. To identify plant Bax inhibitors, we cotransformed a soybean cDNA library and the Bax gene into yeast cells and screened for expressed genes that prevented Bax-induced apoptosis. From the Bax-inhibiting genes isolated, ascorbate peroxidase (sAPX) was selected for characterization. The transcription of sAPX in plants was specifically induced by oxidative stress. Moreover, overexpression of sAPX partially suppressed the H(2)O(2)-sensitive phenotype of yeast cytosolic catalase T (Deltactt)- and thermosensitive phenotype of cytochrome c peroxidase (Deltaccp)-deleted mutant cells. Examination of reactive oxygen species (ROS) production using the fluorescence method of dihydrorhodamine 123 oxidation revealed that expression of Bax in yeast cells generated ROS, which was greatly reduced by coexpression with sAPX. Our results collectively suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Bax-induced cell death in yeast.

Apoptosis↗

PubMed2002

Characterization of a stamen-specific cDNA encoding a novel plant defensin in Chinese cabbage.

We isolated a stamen-specific cDNA, BSD1 (Brassica stamen specific plant defensin 1) that encodes a novel plant defensin peptide in Chinese cabbage (Brassica campestris L. ssp. pekinensis). Plant defensins are antimicrobial peptides containing eight highly conserved cysteine residues linked by disulfide bridges. In BSD1, the eight cysteine residues and a glutamate residue at position 29 are conserved whereas other amino acid residues of the plant defensins consensus sequence are substituted. BSD1 transcripts accumulate specifically in the stamen of developing flowers and its level drops as the flowers mature. The recombinant BSD1 produced in Escherichia coli showed antifungal activity against several phytopathogenic fungi. Furthermore, constitutive over-expression of the BSD1 gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter conferred enhanced tolerance against the Phytophthora parasitica in the transgenic tobacco plants.

Amino Acid Sequence↗

PubMed2002

Over-expression of a seed specific hevein-like antimicrobial peptide from Pharbitis nil enhances resistance to a fungal pathogen in transgenic tobacco plants.

Two hevein-like peptides from the seed of Pharbitis nil, designated Pharbitis nil antimicrobial peptide 1 (Pn-AMP1) and Pn-AMP2, had been purified previously. Both exhibit potent in vitro antifungal activity against a broad spectrum of phytopathogenic fungi. We now report the isolation of two cDNA clones, designated pnAMP-h1 and pnAMP-h2, and the corresponding genomic clones encoding these proteins from mature seeds of P. nil. Comparison of the deduced amino acid sequence to that of the mature protein suggests that the peptides are produced as a prepropeptide consisting of an N-terminal signal peptide, the mature protein and C-terminal domains. The transcripts of the two genes are accumulated seed--specifically, and the maximum transcripts are observed in the mid-to-late stage of seed development. Constitutive over-expression of the pnAMP-h2 cDNA in transgenic tobacco under the control of the cauliflower mosaic virus 35S promoter conferred enhanced resistance against the oomycete Phytophthora parasitica, the causal agent of black shank disease. Thus the Pn-AMPs may play a role in the protection of seeds and may be useful as a novel gene source to engineer plants resistant to fungal pathogens.

Amino Acid Sequence↗