Manipulation of IME4 expression, a global regulation strategy for metabolic engineering in Saccharomyces cerevisiae

Metabolic engineering has been widely used for production of natural medicinal molecules.However, engineering high-yield platforms is hindered in large part by limited knowledge of complex regulatory machinery of metabolic network. N~6-Methyladenosine(m^(6)A) modification of RNA plays critical roles in regulation of gene expression. Herein, we identify 1470 putatively m^(6)A peaks within 1151 genes from the haploid Saccharomyces cerevisiae strain. Among them, the transcript levels of 94 genes falling into the pathways which are frequently optimized for chemical production, are remarkably altered upon overexpression of IME4(the yeast m^(6)A methyltransferase). In particular, IME4 overexpression elevates the mRNA levels of the methylated genes in the glycolysis, acetyl-CoA synthesis and shikimate/aromatic amino acid synthesis modules. Furthermore, ACS1 and ADH2, two key genes responsible for acetyl-CoA synthesis, are induced by IME4 overexpression in a transcription factor-mediated manner.Finally, we show IME4 overexpression can significantly increase the titers of isoprenoids and aromatic compounds. Manipulation of m^(6)A therefore adds a new layer of metabolic regulatory machinery and may be broadly used in bioproduction of various medicinal molecules of terpenoid and phenol classes.

Euphoractone,a cytotoxic meroterpenoid with an unusual entabietane-phloroglucinol skeleton,from Euphorbia fischeriana Steud.

A novel meroterpenoid,euphoractone(1),was isolated from the extracts of the roots of Euphorbia fischeriana Steud.Its structure was determined by spectroscopic methods and X-ray crystallography.1 possesses an unusual ent-abietane-phloroglucinol skeleton.The plausible biosynthetic pathway for 1 was proposed.1 showed inhibitory activities against human lung cancer H23 and H460 cells with the IC_(50)values of 21.07±3.54 and 20.91±4.07 μmol/L.

A new cytotoxic salannin-class limonoid alkaloid from seeds of Azadirachta indica A. Juss

A new cytotoxic salannin-class limonoid alkaloid, azadiramide A（1）,was isolated from seeds of Azadirachta indica A. Juss. Its structure was elucidated by extensive analysis of spectroscopic data and quantum chemical calculation. Compound 1 is a rare salannin-class limonoid alkaloid. To our best knowledge, only two compounds belonging to this type were so far found. It showed inhibitory activity against human breast cancer MDA-MB-231 cell line with IC_（50） value of 2.70±0.63 μmol/L.

Limonoids from seeds of Azadirachta indica A.Juss. and their cytotoxic activity

Four new limonoid-type nortriterpenoids, 1-detigloyl-1-O-methacryloylsalannin(1), 28-deoxo-2,3-dihydronimbolide(2), 12-acetoxy-3-O-acetyl-7-O-tigloylvilasinin(3) and 12-acetoxy-3-Oacetyl-7-O-methacryloylvilasinin(4), along with five known ones, were isolated from seeds of Azadirachta indica A. Juss. Their structures were elucidated by various spectroscopic methods, including UV, IR, MS, NMR, X-ray crystallography, quantum chemical calculation, as well as by comparison of their spectroscopic data with those reported. In the in vitro cytotoxic assay, 2 showed inhibitory activity against human breast cancer MDA-MB-231 cell line with IC_(50) value of 7.68±1.74 μmol/L, and 5 inhibited growth of human cervical cancer Hela cell line, melanoma A375 cell line and promyelocytic leukemia HL-60 cell line, with IC_(50) 12.00±2.08, 17.44±2.11, and 13.95±5.74 μmol/L, respectively.