School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
School of Molecular Sciences and The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, WA 6009, Australia.
J Nat Prod. 2021 Nov 26;84(11):2914-2922. doi: 10.1021/acs.jnatprod.1c00672. Epub 2021 Oct 21.
Plants are an excellent source of bioactive peptides, often with disulfide bonds and/or a cyclic backbone. While focus has predominantly been directed at disulfide-rich peptides, a large family of small, cyclic plant peptides lacking disulfide bonds, known as orbitides, has been relatively ignored. A recently discovered subfamily of orbitides is the PawL-derived peptides (PLPs), produced during the maturation of precursors for seed storage albumins. Although their evolutionary origins have been dated, in-depth exploration of the family's structural characteristics and potential bioactivities remains to be conducted. Here we present an extensive and systematic characterization of the PLP family. Nine PLPs were chosen and prepared by solid phase peptide synthesis. Their structural features were studied using solution NMR spectroscopy, and seven were found to possess regions of backbone order. Ordered regions consist of β-turns, with some PLPs adopting two well-defined β-turns within sequences as short as seven residues, which are largely the result of side chain interactions. Our data highlight that the sequence diversity within this family results in equally diverse structures. None of these nine PLPs showed antibacterial or antifungal activity.
植物是生物活性肽的极好来源，这些肽通常含有二硫键和/或环状骨架。虽然研究重点主要集中在富含二硫键的肽上，但一类相对被忽视的、不含二硫键的小环状植物肽，即轨道肽家族，其成员数量庞大。轨道肽家族的一个新近发现的亚家族是 PawL 衍生肽（PLP），它们是在种子贮藏白蛋白前体成熟过程中产生的。尽管已经确定了它们的进化起源，但对该家族结构特征和潜在生物活性的深入探索仍有待进行。在这里，我们对 PLP 家族进行了广泛而系统的特征描述。选择了 9 个 PLP 并通过固相肽合成进行了制备。使用溶液 NMR 光谱研究了它们的结构特征，发现其中 7 个具有肽链回文结构区域。有序区域由β-转角组成，其中一些 PLP 在短至 7 个残基的序列中采用两个明确的β-转角，这主要是由于侧链相互作用的结果。我们的数据表明，该家族内的序列多样性导致了结构的多样性。这 9 个 PLP 都没有表现出抗菌或抗真菌活性。
