果蝇精液中存在的肽可以用作抗菌剂,酶抑制剂和信息素,可引起交配后雌性的生理和行为反应。了解这些肽影响繁殖的分子相互作用需要详细了解它们的分子结构。然而,这些信息通常缺乏,不能仅从基因序列和标准蛋白质组数据中收集。我们现在报道了四种精液肽的天然结构(雄激素,CG42782,Met75C和Acp54A1)来自雄性D.melanogaster的射精管。成熟的CG42782、Met75C和Acp54A1肽各自具有由二硫键形成的环状结构,这将降低构象自由度并增强代谢稳定性。此外,CG42782和Met75C中倒数第二个Pro的存在将有助于防止羧肽酶的降解。Met75C经历了更广泛的翻译后修饰,形成了N末端焦谷氨酰残基,并将粘蛋白样O-聚糖连接到Thr4的侧链。预期这两种修饰都进一步增强分泌肽的稳定性。聚糖具有罕见的两性离子结构,包含O-连接的N-乙酰基己糖胺,己糖和,不寻常的,磷酸乙醇胺。对各种基因组的调查表明,雄激素,CG42782和Acp54A1是相对较新的基因,仅限于黑腹亚组。Met75C,然而,在暗黑物种群的成员和食壳果蝇中也发现了。Andropin与cecropin基因家族有关,可能是由串联基因复制引起的,而CG42782、Met75C和Acp54A1可能从头出现。我们推测,我们报道的这些基因产物的翻译后修饰不仅对生物学功能很重要,而且为了代谢稳定性,也可能促进跨组织屏障的运输,比如雌性昆虫的血脑屏障。生物学意义:D.melanogaster的精液肽作为抗菌剂,酶抑制剂和信息素,引起交配后雌性的生理和行为反应。更全面地了解这些肽如何影响生殖,不仅需要了解它们的一级结构,以及它们的翻译后修饰。然而,这些信息通常缺乏,并且难以从标准蛋白质组数据中收集.报告的修改,包括不寻常的糖基化,增加了我们对这个模型生物中这一类重要肽的认识,parexcellent.
Peptides present in the seminal fluid of Drosophila melanogaster can function as antimicrobial agents, enzyme inhibitors and as pheromones that elicit physiological and behavioural responses in the post-mated female. Understanding the molecular interactions by which these peptides influence reproduction requires detailed knowledge of their molecular structures. However, this information is often lacking and cannot be gleaned from just gene sequences and standard proteomic data. We now report the native structures of four seminal fluid peptides (andropin, CG42782, Met75C and Acp54A1) from the ejaculatory duct of male D. melanogaster. The mature CG42782, Met75C and Acp54A1 peptides each have a cyclic structure formed by a disulfide bond, which will reduce conformational freedom and enhance metabolic stability. In addition, the presence of a penultimate Pro in CG42782 and Met75C will help prevent degradation by carboxypeptidases. Met75C has undergone more extensive post-translational modifications with the formation of an N-terminal pyroglutamyl residue and the attachment of a mucin-like O-glycan to the side chain of Thr4. Both of these modifications are expected to further enhance the stability of the secreted peptide. The glycan has a rare zwitterionic structure comprising an O-linked N-acetyl hexosamine, a hexose and, unusually,
phosphoethanolamine. A survey of various genomes showed that andropin, CG42782, and Acp54A1 are relatively recent genes and are restricted to the melanogaster subgroup. Met75C, however, was also found in members of the obscura species groups and in Scaptodrosophila lebanonensis. Andropin is related to the cecropin gene family and probably arose by tandem gene duplication, whereas CG42782, Met75C and Acp54A1 possibly emerged de novo. We speculate that the post-translational modifications that we report for these gene products will be important not only for a biological function, but also for metabolic stability and might also facilitate transport across tissue barriers, such as the blood-brain barrier of the female insect. BIOLOGICAL SIGNIFICANCE: Seminal fluid peptides of D. melanogaster function as antimicrobials, enzyme inhibitors and as pheromones, eliciting physiological and behavioural responses in the post-mated female. A fuller understanding of how these peptides influence reproduction requires knowledge not only of their primary structure, but also of their post-translational modification. However, this information is often lacking and difficult to glean from standard proteomic data. The reported modifications, including the unusual glycosylation, adds much to our knowledge of this important class of peptides in this model organism, par excellence.