Antimicrobial activity against Porphyromonas gingivalis and mechanism of action of the cationic octadecapeptide AmyI-1-18 and its amino acid-substituted analogs

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• 作者：Masayuki Taniguchi¹ ; ² ; ^{mtanig@eng.niigata-u.ac.jp} ; Akihito Ochiai¹ ; Kiyoshi Takahashi¹ ; Shun-ichi Nakamichi¹ ; Takafumi Nomoto¹ ; Eiichi Saitoh³ ; Tetsuo Kato⁴ ; Takaaki Tanaka¹
• 关键词：Antibacterial peptide ; Substitution of amino acid ; Porphyromonas gingivalis ; Cationic peptide ; Hydrophobicity
• 刊名：Journal of Bioscience and Bioengineering
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：122
• 期：6
• 页码：652-659
• 全文大小：445 K
• 卷排序：122

文摘

The antimicrobial peptide AmyI-1-18 is a cationic α-helical octadecapeptide derived from α-amylase in rice (Oryza sativa L. japonica) that contains four cationic amino acid residues (two arginines and two lysines). To enhance the antibacterial activity of AmyI-1-18 against Porphyromonas gingivalis (a bacterium associated with periodontal disease), we synthesized 12 analogs bearing substitutions with alanine, leucine, and/or arginine that were designed based on helical wheel projections and investigated their antibacterial properties. The antibacterial properties of four analogs bearing substitution of a single arginine or lysine with alanine were almost similar to those of AmyI-1-18, suggesting that the antibacterial properties depend on the presence of three cationic amino acid residues. Of three single arginine-substituted analogs, AmyI-1-18(G12R) exhibited an antibacterial activity 2.8-fold higher [50% growth-inhibitory concentration (IC50): 4.6 μM] than that of AmyI-1-18 (IC50: 13 μM). Likewise, the antibacterial properties of two single leucine-substituted analogs were significantly enhanced; in particular, AmyI-1-18(N3L) exhibited an antibacterial activity (IC50: 2.5 μM) 5.2-fold higher than that of AmyI-1-18. The hemolytic activity of AmyI-1-18(N3L) against mammalian red blood cells was low (2% at 50 μM). A membrane-depolarization assay using a membrane potential-sensitive fluorescent dye revealed that, similar to AmyI-1-18, the antibacterial activity of AmyI-1-18(N3L) was not dependent on its membrane-disrupting activity. Our results demonstrate that the antibacterial properties of AmyI-1-18 against P. gingivalis are significantly improved, without a significant increase in hemolytic activity, by replacing asparagine with leucine at position 3.