Walker J R, Roth J R, Altman E
Center for Molecular BioEngineering, University of Georgia, Athens 30602, USA.
J Pept Res. 2001 Nov;58(5):380-8. doi: 10.1034/j.1399-3011.2001.00897.x.
We have created a system in which synthetically produced novel bioactive peptides can be expressed in vivo in Escherichia coli. Twenty thousand of these peptides were screened and 21 inhibitors were found that could inhibit the growth of E. coli on minimal media. The inhibitors could be placed into one of two groups, 1-day inhibitors, which were partially inhibitory, and 2-day inhibitors, which were completely inhibitory. Sequence analysis showed that two of the most potent inhibitors were actually peptide-protein chimeras in which the peptides had become fused to the 63 amino acid Rop protein which was also contained in the expression vector used in this study. Given that Rop is known to form an incredibly stable structure, it could be serving as a stabilizing motif for these peptides. Sequence analysis of the predicted coding regions from the next 10 most inhibitory peptides showed that four of the 10 peptides contained one or more proline residues either at or very near the C-terminal end of the peptide which could act to prevent degradation by peptidases. Collectively, based on what we observed in our screen of synthetic bioactive peptides that could prevent the growth of E. coli and what has been learned from structural studies of naturally occurring bioactive peptides, the presence of a stabilizing motif seems to be important for small peptides, if they are to be biologically active.
我们创建了一个系统，在该系统中，合成产生的新型生物活性肽能够在大肠杆菌体内表达。对其中2万种肽进行了筛选，发现有21种抑制剂能够抑制大肠杆菌在基本培养基上的生长。这些抑制剂可分为两组，一组是1天抑制剂，具有部分抑制作用；另一组是2天抑制剂，具有完全抑制作用。序列分析表明，两种最有效的抑制剂实际上是肽 - 蛋白质嵌合体，其中肽与63个氨基酸的Rop蛋白融合，本研究中使用的表达载体中也含有该蛋白。鉴于已知Rop能形成极其稳定的结构，它可能作为这些肽的稳定基序。对接下来10种抑制作用最强的肽的预测编码区进行序列分析表明，这10种肽中有4种在肽的C末端或非常靠近C末端处含有一个或多个脯氨酸残基，这些脯氨酸残基可起到防止肽酶降解的作用。总体而言，基于我们在筛选能够阻止大肠杆菌生长的合成生物活性肽时所观察到的情况，以及从天然存在的生物活性肽的结构研究中所学到的知识，如果小肽要具有生物活性，稳定基序的存在似乎很重要。
