New Modes of GPCR Signalling
New Modes of GPCR Signalling
New Modes of GPCR Signalling
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Isolation, Characterization and Anti-Cancer Activity <strong>of</strong> SK84, a Novel<br />
Glycine-Rich Antimicrobial Peptide from Drosophila Virilis<br />
Jie Lu*, Mu-ya Shu, Ming-lei Leng, Zheng-wang Chen<br />
Institute <strong>of</strong> Biophysical & Biochemistry, College <strong>of</strong> Life Science and<br />
Technology,Huazhong University <strong>of</strong> Science & Technology, Wuhan, 430074, China<br />
We report herein the isolation and characterization <strong>of</strong> a novel glycine-rich antimicrobial<br />
peptide purified from the larvae <strong>of</strong> Drosophila virilis. A range <strong>of</strong> chromatographic<br />
methods was used for isolation and its antibacterial activity against Bacillus subtilis was<br />
employed to screen for the most active fractions. The peptide, termed SK84 due to its<br />
N-terminal serine, C-terminal lysine and a total <strong>of</strong> 84 residues, was completed<br />
sequenced using RT-PCR cDNA cloning. SK84 contains a high level <strong>of</strong> glycine (15.5%)<br />
and a hexaglycine cluster motif in the N-terminal part. SK84 displayed antibacterial<br />
activity against the tested Gram-positive bacteria (Bacillus subtilis, Bacillus<br />
thuringiensis and Staphylococcus aureus), but had no effect on Gram-negative bacteria<br />
(Pseudomonas aeruginosa, Escherichia coli) and fungi (Saccharomyces cerevisiae,<br />
Candida albicans). SK84 had specific inhibitory effects on the proliferation <strong>of</strong> several<br />
cancer cell lines (Human leukemia THP-1, liver cancer HepG2, and breast cancer<br />
MCF-7 cells), but no hemolytic activity. The results from scanning electron microscopy<br />
observations revealed that SK84 killed THP-1 cells by destroying the cell membranes.<br />
Alignment results show that SK84 is a mature protein processed from the pseudoprotein<br />
GJ19999 from Drosophila virilis, and is very similar to several pseudoproteins from<br />
different Drosophila species. SK84 induces the apoptosis <strong>of</strong> HepG2 cells by stimulating<br />
the caspase-3 activation. Our results show that SK84 represents a novel glycine-rich<br />
peptide family in Drosophila species with antimicrobial and anti-cancer cell activities.<br />
Key Words:antimicrobial peptide; glycine-rich peptide; Drosophila virilis;<br />
anti-cancer-cell activity;apoptosis.<br />
*Corresponding author to:<br />
Tel: 86-18971142265;Fax: 86-027-87792024;E-mail:lujie.jane@163.com
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