Project description:Polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) hybrid systems typically use complex protein-protein interactions to facilitate direct transfer of intermediates between these multimodular megaenzymes. In the canal-associated neurons (CANs) of Caenorhabditis elegans, PKS-1 and NRPS-1 produce the nemamides, the only known hybrid polyketide-nonribosomal peptides biosynthesized by animals, through a poorly understood mechanism. Here, we use genome editing and mass spectrometry to map the roles of individual PKS-1 and NRPS-1 enzymatic domains in nemamide biosynthesis. Furthermore, we show that nemamide biosynthesis requires at least five additional enzymes expressed in the CANs that are encoded by genes distributed across the worm genome. We identify the roles of these enzymes and discover a mechanism for trafficking intermediates between a PKS and an NRPS. Specifically, the enzyme PKAL-1 activates an advanced polyketide intermediate as an adenylate and directly loads it onto a carrier protein in NRPS-1. This trafficking mechanism provides a means by which a PKS-NRPS system can expand its biosynthetic potential and is likely important for the regulation of nemamide biosynthesis.
Project description:In the seabed, chemical defences mediate inter- and intraspecific interactions and may determine organisms’ success, shaping the diversity and function of benthic communities. Sponges represent a prominent example of chemically-defended marine organisms with great ecological success. The ecological factors controlling the production of their defensive compounds and the evolutionary forces that select for these defences remain little understood. Each sponge species produces a specific and diverse chemical arsenal with fish-deterrent, antifouling and antimicrobial properties. However, some small animals (mesograzers), mainly sea slugs, have specialized in living and feeding on sponges. Feeding on chemically-defended organisms provides a strategy to avoid predators, albeit the poor nutritional value of sponges. In order to investigate the mechanisms that control sponge chemical defence, with particular focus on the response to specialist grazers, we investigated the interaction between the sponge Aplysina aerophoba and the sea slug Tylodina perversa. Here we performed controlled experiments and collected sponge samples at different time points (3h, 1d and 6d after treatment). To further elucidate if the sponge response is specific to grazing by T. perversa, we also included a treatment in which sponges were mechanically damaged with a scalpel. We compared gene expression between treatments based on RNA-Seq data.
Project description:Clinical use of intraoperative auto-transfusion requires the removal of platelets and plasma proteins due to the pump-based suction and water-soluble anticoagulant administration, which causes dilutional coagulopathy. Herein, we develop a carboxylated and sulfonated heparin-mimetic polymer-modified sponge that could spontaneously adsorb blood (1.149 kg/m-2 s-1/2) along with instantaneous anticoagulation. We demonstrate that intrinsic coagulation factors (especially XI) are inactivated by adsorption to the sponge surface, while inactivation of thrombin in the sponge-treated plasma effectively inhibits the common coagulation pathway. Benefiting from the multiple inhibitory effects of sponge on coagulation enzymes and calcium depletion, the whole blood auto-transfusion in trauma-induced hemorrhage is unprecedentedly realized. The transfusion of collected blood favors faster recovery of hemostasis compared to traditional heparinized blood in an animal model. Our work not only develops a safe and convenient approach for whole blood auto-transfusion, but also provides the mechanism of action of self-anticoagulant heparin-mimetic polymer-modified surfaces.