Department of Biosciences, University of Oslo, PO Box 1066, Blindern, NO-, 0316, Oslo, Norway.
Sci Rep. 2019 Feb 20;9(1):2333. doi: 10.1038/s41598-019-38518-6.
The structure of the individual peptides of the two-peptide bacteriocin plantaricin S, an antimicrobial peptide produced by a Lactobacillus plantarum strain, has been determined in DPC micelles. The two peptides of plantaricin S, Pls-α and Pls-β, form an α-helix from and including residue 8 to 24 with a less structured region around residue 16-19 and an amphiphilic α-helix from and including residue 7 to 23, respectively. Activity assays on single amino acid-substituted GxxxG and GxxxG-like motifs show that substituting the Ser and Gly residues in the GxxxG motif in Pls-α and the SxxxG motif in Pls-β reduced or drastically reduced the antimicrobial activity. The two-peptide bacteriocin muricidin contains GxxxG-like motifs at similar positions and displays 40-50% amino acid identity with plantaricin S. Activity assays of combinations of the peptides that constitute the bacteriocins plantaricin S and muricidin show that some combinations are highly active. Furthermore, sequence alignments show that the motifs important for plantaricin S activity align with identical motifs in muricidin. Based on sequence comparison and activity assays, a membrane-inserted model of plantaricin S in which the two peptides are oriented antiparallel relative to each other and where the GxxxG and GxxxG-like motifs important for activity come close in space, is proposed.
植物乳酸杆菌产生的抗菌肽植物素 S 由两个肽组成，其在 DPC 胶束中的结构已被确定。植物素 S 的两个肽，Pls-α和 Pls-β，分别从残基 8 到 24 形成一个α-螺旋，在残基 16-19 周围有一个结构较少的区域，以及一个从残基 7 到 23 的两亲性α-螺旋。对单个氨基酸取代 GxxxG 和 GxxxG 样基序的活性测定表明，取代 Pls-α中的 GxxxG 基序中的 Ser 和 Gly 残基和 Pls-β中的 SxxxG 基序中的 Ser 和 Gly 残基降低或大大降低了抗菌活性。双肽细菌素 muricidin 含有类似位置的 GxxxG 样基序，与植物素 S 具有 40-50%的氨基酸同一性。构成细菌素植物素 S 和 muricidin 的肽的组合活性测定表明，一些组合具有很高的活性。此外，序列比对表明，对植物素 S 活性重要的基序与 muricidin 中的相同基序对齐。基于序列比较和活性测定，提出了一种植物素 S 的膜插入模型，其中两个肽彼此相对反向平行取向，并且对活性重要的 GxxxG 和 GxxxG 样基序在空间上接近。
