Contribution of Each Amino Acid Residue in Polymyxin B3 to Antimicrobial and Lipopolysaccharide Binding Activity
作者:Kazushi Kanazawa、Yuki Sato、Kazuhiro Ohki、Keiko Okimura、Yoshiki Uchida、Mitsuno Shindo、Naoki Sakura
DOI:10.1248/cpb.57.240
日期:——
This study on the structure–activity relationship of polymyxin B, a cyclic peptide antibiotic, used sixteen synthetic polymyxin B3 analogs including alanine scanning analogs to elucidate the contribution of the side chains to antimicrobial activity and lipopolysaccharide (LPS) binding. Of these analogs, [Ala5]-polymyxin B3 showed greatly reduced antimicrobial activity against Escherichia coli (E. coli), Salmonella Typhimurium (S. Typhimurium) and Pseudomonas aeruginosa (P. aeruginosa) with MIC values of 4—16 nmol/ml, suggesting that the Dab (α,γ-diaminobutyric acid) residue at position 5 is the most important residue contributing to bactericidal activity. The antibacterial contribution of Dab when located within the lactam ring (positions 5, 8 and 9) was greater than when located outside the ring (positions 1 and 3). [D-Ala6]-, [L-Phe6]-, [Ala7]-, and [Gly7]-polymyxin B3 analogs retained potent antimicrobial activity, indicating that neither the reduction of hydrophobic character of the D-Phe6-Leu7 region nor the D-configuration at position 6 is indispensable for antimicrobial activity. LPS binding studies showed that decreased hydrophobicity of the lactam ring had little effect, but the Nγ-amino function of the Dab residues at position 1, 3, 5, 8 and 9 greatly affected LPS binding, with the contribution of Dab5 being the most significant.
这项关于多粘菌素 B(一种环肽抗生素)结构-活性关系的研究使用了 16 种合成多粘菌素 B3 类似物,包括丙氨酸扫描类似物,以阐明侧链对抗菌活性和脂多糖 (LPS) 结合的贡献。在这些类似物中,[Ala5]-多粘菌素 B3 对大肠杆菌 (E. coli)、鼠伤寒沙门氏菌 (S. Typhimurium) 和铜绿假单胞菌 (P. aeruginosa) 的抗菌活性大大降低,MIC 值为 4-16 nmol/ml,这表明第 5 位的 Dab(α,γ-二氨基丁酸)残基是有助于杀菌活性的最重要的残基。 Dab 位于内酰胺环内(位置 5、8 和 9)时的抗菌贡献大于位于环外(位置 1 和 3)时的抗菌贡献。 [D-Ala6]-、[L-Phe6]-、[Ala7]- 和 [Gly7]-多粘菌素 B3 类似物保留了有效的抗菌活性,表明D-Phe6-Leu7 区域的疏水性和第 6 位 D-构型的减少对于抗菌活性是必不可少的。 LPS结合研究表明,内酰胺环疏水性降低影响不大,但1、3、5、8和9位Dab残基的Nγ-氨基功能极大地影响了LPS结合,其中Dab5的贡献最为显着。