Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.
Peptides. 2012 Apr;34(2):283-9. doi: 10.1016/j.peptides.2012.01.015. Epub 2012 Jan 28.
Buforin IIb-a synthetic analog of buforin II that contains a proline hinge between the two α-helices and a model α-helical sequence at the C-terminus (3× RLLR)-is a potent cell-penetrating antimicrobial peptide. To develop novel antimicrobial peptides with enhanced activities and specificity/therapeutic index, we designed several analogs (Buf III analogs) by substitutions of amino acids in the proline hinge region and two α-helices of buforin IIb, and examined their antimicrobial activity and mechanism of action. The substitution of hydrophobic residues ([F(6)] and [V(8)]) in the proline hinge region with other hydrophobic residues ([W(6)] and [I(8)]) did not affect antimicrobial activity, while the substitution of the first four amino acids RAGL with a model α-helical sequence increased the antimicrobial activity up to 2-fold. Like buforin IIb, Buf III analogs penetrated the bacterial cell membranes without significantly permeabilizing them and were accumulated inside Escherichia coli. Buf III analogs were shown to bind DNA in vitro and the DNA binding affinity of the peptides correlated linearly with their antimicrobial potency. Among the Buf III analogs, the therapeutic index of Buf IIIb and IIIc (RVVRQWPIGRVVR and KLLKQWPIGKLLK, respectively) were improved 7-fold compared to that of buforin IIb. These results indicate that Buf III analogs appear to be promising candidates for future development as novel antimicrobial agents.
Buforin IIb 是一种人工合成的 Buforin II 类似物，其两个 α-螺旋之间有一个脯氨酸铰链，C 末端有一个模型 α-螺旋序列（3×RLLR），是一种有效的细胞穿透性抗菌肽。为了开发具有增强活性和特异性/治疗指数的新型抗菌肽，我们通过替换 Buforin IIb 中脯氨酸铰链区域和两个 α-螺旋中的氨基酸设计了几种类似物（Buf III 类似物），并研究了它们的抗菌活性和作用机制。用其他疏水性残基（[W(6)]和[I(8)])替换脯氨酸铰链区域中的疏水性残基([F(6)]和[V(8)])不影响抗菌活性，而用模型α-螺旋序列取代前四个氨基酸 RAGL 则将抗菌活性提高了 2 倍。与 Buforin IIb 一样，Buf III 类似物穿透细菌细胞膜而不会显著使其通透性增加，并在大肠杆菌中积累。Buf III 类似物在体外显示与 DNA 结合，并且肽的 DNA 结合亲和力与它们的抗菌效力呈线性相关。在 Buf III 类似物中，Buf IIIb 和 IIIc（RVVRQWPIGRVVR和 KLLKQWPIGKLLK，分别）的治疗指数比 Buforin IIb 提高了 7 倍。这些结果表明，Buf III 类似物似乎是作为新型抗菌剂开发的有前途的候选物。
