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
Abstract
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.
Utility of Treponemal Testing from Aqueous Fluid in the Diagnosis of Ocular Syphilis in Patients with HIV/AIDS
OCULAR IMMUNOLOGY AND INFLAMMATION
Authors: Nair, Nivedita; Sudharshan, Sridharan; Anand, Appakkudal R.; Biswas, Jyotirmay; Therese, K. Lily
Abstract
Purpose: Ocular syphilis is re-emerging globally especially in patients with human immunodeficiency virus (HIV). Atypical manifestations of ocular syphilis and/or other associated opportunistic infections often lead to a diagnostic dilemma. We evaluated the utility of aqueous humor (AH)Treponema pallidumhemagglutination assay (TPHA) titers in the diagnosis of ocular syphilis. Methods: Retrospective case series of five HIV positive patients with positive syphilis serology in whom AH sampling was performed. All patients had ocular manifestations suspicious of infectious etiology. Results: Panuveitis with/without retinitis was the commonest presentation. Along with blood investigations, polymerase chain reaction (PCR) testing from AH was done forMycobacterium tuberculosis(MTB),Herpes Simplex Virus(HSV),Varicella Zoster Virus(VZV),Cytomegalovirus(CMV), andToxoplasma gondii. In addition, serum antibody titers for Toxoplasma, rapid plasma reagin (RPR) and TPHA tests for syphilis were done. In patients with raised serum RPR/TPHA, aqueous TPHA titers were also assessed. Mean serum RPR titer was >= 1:32 and TPHA titer was >= 1:1280. Aqueous humor titers of TPHA was high in all patients (range >= 1:320 to >= 1:5120). Aqueous PCR was negative for all other infectious etiologies in four patients. In one patient, PCR-CMV was also positive, suggestive of a dual infection. Post-treatment with highly active antiretroviral therapy (HAART) and appropriate anti-syphilitic regime, complete resolution of lesions with corresponding fall in the serum RPR/TPHA titers were noted in all patients. Conclusions: Ocular syphilis with atypical presentations is usually diagnosed based on a positive syphilis serology and by excluding other infectious causes. In the present study, we have shown an excellent correlation between raised AH TPHA titers with serological values and the clinical presentation. Considering the ease of collection of AH in contrast to vitreous fluids, the AH-TPHA assay could potentially be a valuable tool in the diagnosis of ocular syphilis.