Production of the bioactive plant-derived triterpenoid morolic acid in engineered Saccharomyces cerevisiae
BIOTECHNOLOGY AND BIOENGINEERING
Authors: Srisawat, Pisanee; Yasumoto, Shuhei; Fukushima, Ery O.; Robertlee, Jekson; Seki, Hikaru; Muranaka, Toshiya
Morolic acid is a plant-derived triterpenoid that possesses pharmacological properties such as cytotoxicity, as well as anti-HIV, anti-HSV, anti-inflammatory, and antidiabetic effects. The significant therapeutic properties of morolic acid are desirable in the context of pharmacological and drug development research, but the low accessibility of morolic acid from natural resources limits its applications. In the present study, we developed a microbial system for the production of morolic acid. Using a combinatorial biosynthesis approach, a novel production pathway was constructed in Saccharomycescerevisiae by coexpressing BfOSC2 (germanicol synthase) from Bauhinia forficata and CYP716A49 (triterpene C-28 oxidase) from Beta vulgaris. Moreover, we reconstructed the cellular galactose regulatory network by introducing a chimeric transcriptional activator (fusion of Gal4dbd.ER.VP16) to overdrive the genes under the control of the galactose promoter. We also overexpressed truncated HMG1, encoding feedback-inhibition-resistant form of 3-hydroxy-3-methylglutaryl-coenzyme A reductase 1 and sterol-regulating transcription factor upc2-1, to increase the isoprenoid precursors in the mevalonate pathway. Using this yeast system, we achieved morolic acid production up to 20.7 +/- 1.8 mg/L in batch culture. To our knowledge, this is the highest morolic acid titer reported from a heterologous host, indicating a promising approach for obtaining rare natural triterpenoids.
HSV-1 and Zika Virus but Not SARS-CoV-2 Replicate in the Human Cornea and Are Restricted by Corneal Type III Interferon
Authors: Miner, Jonathan J.; Platt, Derek J.; Ghaznavi, Cyrus M.; Chandra, Pallavi; Santeford, Andrea; Menos, Amber M.; Dong, Zhenyu; Wang, Erin R.; Qian, Wei; Karozichian, Elysse S.; Philips, Jennifer A.; Apte, Rajendra S.
Here, we report our studies of immune-mediated regulation of Zika virus (ZIKV), herpes simplex virus 1 (HSV-1), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the human cornea. We find that ZIKV can be transmitted via corneal transplantation in mice. However, in human corneal explants, we report that ZIKV does not replicate efficiently and that SARS-CoV-2 does not replicate at all. Additionally, we demonstrate that type III interferon (IFN-lambda) and its receptor (IFN lambda R1) are expressed in the corneal epithelium. Treatment of human corneal explants with IFN-lambda, and treatment of mice with IFN-lambda eye drops, upregulates antiviral interferon-stimulated genes. In human corneal explants, blockade of IFN lambda R1 enhances replication of ZIKV and HSV-1 but not SARS-CoV-2. In addition to an antiviral role for IFN lambda R1 in the cornea, our results suggest that the human cornea does not support SARS-CoV-2 infection despite expression of ACE2, a SARS-CoV-2 receptor, in the human corneal epithelium.