Pelegrini Patricia B, Murad André M, Silva Luciano P, Dos Santos Rachel C P, Costa Fabio T, Tagliari Paula D, Bloch Carlos, Noronha Eliane F, Miller Robert N G, Franco Octavio L
Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
Peptides. 2008 Aug;29(8):1271-9. doi: 10.1016/j.peptides.2008.03.013. Epub 2008 Mar 22.
Bacterial pathogens cause an expressive negative impact worldwide on human health, with ever increasing treatment costs. A significant rise in resistance to commercial antibiotics has been observed in pathogenic bacteria responsible for urinary and gastro-intestinal infections. Towards the development of novel approaches to control such common infections, a number of defense peptides with antibacterial activities have been characterized. In this report, the peptide Pg-AMP1 was isolated from guava seeds (Psidium guajava) and purified using a Red-Sepharose Cl-6B affinity column followed by a reversed-phase HPLC (Vydac C18-TP). Pg-AMP1 showed no inhibitory activity against fungi, but resulted in a clear growth reduction in Klebsiella sp. and Proteus sp., which are the principal pathogens involved in urinary and gastro-intestinal hospital infections. SDS-PAGE and mass spectrometry (MALDI-ToF) characterized Pg-AMP1 a monomer with a molecular mass of 6029.34Da and small quantities of a homodimer. Amino acid sequencing revealed clear identity to the plant glycine-rich protein family, with Pg-AMP1 the first such protein with activity towards Gram-negative bacteria. Furthermore, Pg-AMP1 showed a 3D structural homology to an enterotoxin from Escherichia coli, and other antibacterial proteins, revealing that it might act by formation of a dimer. Pg-AMP1 shows potential, in a near future, to contribute to development of novel antibiotics from natural sources.
细菌病原体在全球范围内对人类健康造成了严重的负面影响，治疗成本也在不断增加。在引起泌尿系统和胃肠道感染的病原菌中，对商用抗生素的耐药性显著上升。为了开发控制此类常见感染的新方法，人们对一些具有抗菌活性的防御肽进行了表征。在本报告中，肽Pg-AMP1从番石榴籽（番石榴）中分离出来，并使用Red-Sepharose Cl-6B亲和柱进行纯化，随后进行反相高效液相色谱（Vydac C18-TP）。Pg-AMP1对真菌没有抑制活性，但能明显抑制克雷伯氏菌属和变形杆菌属的生长，这两种菌是泌尿系统和胃肠道医院感染的主要病原菌。SDS-PAGE和质谱分析（MALDI-ToF）表明Pg-AMP1是一种分子量为6029.34Da的单体以及少量的同型二聚体。氨基酸测序显示其与富含甘氨酸的植物蛋白家族具有明显的同源性，Pg-AMP1是首个对革兰氏阴性菌具有活性的此类蛋白。此外，Pg-AMP1与大肠杆菌的一种肠毒素以及其他抗菌蛋白具有三维结构同源性，表明它可能通过形成二聚体发挥作用。在不久的将来，Pg-AMP1有望为天然来源新型抗生素的开发做出贡献。
