1. Direct antimicrobial activities of PR-bombesin
Jianxu Li, Xueqing Xu, Haining Yu, Hailong Yang, Zhongxian Huang, Ren Lai Life Sci. 2006 Mar 20;78(17):1953-6. doi: 10.1016/j.lfs.2005.08.034. Epub 2005 Nov 2.
PR-bombesin is a bombesin-like peptide derived from the skin of the Chinese red belly toad, Bombina maxima. The 8-residue segment of N-terminal of RP-bombesin, comprising four prolines and three basic residues, is extensively different from other bombesin-like peptides. Since sequence of Pro-Arg-Pro generally plays an important role in the antimicrobial activity of proline-rich antimicrobial peptides, the componential feature of PR-bombesin indicates that it may have antimicrobial activity. In this paper, we presented the first evidence that bombesin-like peptides possess direct antimicrobial activities as some neuropeptides. It was determined by CD spectroscopy that PR-bombesin adopted a combination of random coil and beta-sheet structure, suggesting RP-bombesin is a new member of antimicrobial peptides having beta structure but without disulfide bonds. Current results also supported that PR-bombesin plays a direct defensive role besides its neuro-endocrological functions.
2. Cloning of novel bombesin precursor cDNAs from skin of Bombina maxima
Ji-Hong Shen, Shu-Bai Liu, Ying-Xia Zhang, Yang Jin, Wen-Hui Lee, Yun Zhang Regul Pept. 2005 Dec 15;132(1-3):102-6. doi: 10.1016/j.regpep.2005.09.007. Epub 2005 Oct 3.
Amphibian skin is a rich resource of bioactive peptides like proline-rich bombesin from frog Bombina maxima. A novel cDNA clone encoding a precursor protein that comprises proline-rich bombesin and a novel peptide, designated as bombestatin, was isolated from a skin cDNA library of B. maxima. The predicted primary structure of the novel peptide is WEVLLNVALIRLELLSCRSSKDQDQKESCGMHSW, in which two cysteines form a disulfide bond. A BLAST search of databases did not detect sequences with significant similarity. Bombestatin possesses dose-dependent contractile activity on rat stomach strips. The differences between cDNAs encoding PR-bombesin plus bombestatin and PR-bombesin alone are due to fragment insertions located in 3'-coding region and 3'-untranslational region, respectively.
3. A novel proline rich bombesin-related peptide (PR-bombesin) from toad Bombina maxima
Ren Lai, Hen Liu, Wen Hui Lee, Yun Zhang Peptides. 2002 Mar;23(3):437-42. doi: 10.1016/s0196-9781(01)00642-8.
A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH(2.) The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bombesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu(13)]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin.