ABSTRACT
Objective: To explore the pharmacological mechanism of traditional Chinese medicine (TCM) Magnoliae Officinalis Cortex by systems pharmacology (SP). Methods: A database of magnolia components was established by using the database of TCM ingredients and a large number of literature search. After that, ADME was used to screen the active compounds of magnolia, and these ingredients and an in silico software were used to identify targets. Finally, the pharmacological mechanism of magnolia was analyzed by SP methods network analysis and pathway analysis. Results: The most comprehensive database of magnolia ingredients to date have been established, containing a total of 144 magnolia compounds. After screening, we obtained seven magnolia active compounds which meet the conditions and identified 54 interacting targets. The network analysis showed that these targets were mainly related to intestinal motility, inflammation, diabetes and thrombus. Through pathway analysis, we found that a total of 152 biological pathways were involved in the targets of magnolia, and these pathways were involved in cancer-related mechanisms in addition to the above diseases. Conclusion: This study not only uses SP to reveal the pharmacological mechanisms of magnolia on intestinal motility, inflammation, diabetes, thrombus and cancer, but also reflects the typical “multi-component, multi-target, multi-channel” TCM characteristics of magnolia and provides a new SP technology to explore the pharmacological mechanism of TCM.
ABSTRACT
N-methyladenosine (mA), a ubiquitous RNA modification, is installed by METTL3-METTL14 complex. The structure of the heterodimeric complex between the methyltransferase domains (MTDs) of METTL3 and METTL14 has been previously determined. However, the MTDs alone possess no enzymatic activity. Here we present the solution structure for the zinc finger domain (ZFD) of METTL3, the inclusion of which fulfills the methyltransferase activity of METTL3-METTL14. We show that the ZFD specifically binds to an RNA containing 5'-GGACU-3' consensus sequence, but does not to one without. The ZFD thus serves as the target recognition domain, a structural feature previously shown for DNA methyltransferases, and cooperates with the MTDs of METTL3-METTL14 for catalysis. However, the interaction between the ZFD and the specific RNA is extremely weak, with the binding affinity at several hundred micromolar under physiological conditions. The ZFD contains two CCCH-type zinc fingers connected by an anti-parallel β-sheet. Mutational analysis and NMR titrations have mapped the functional interface to a contiguous surface. As a division of labor, the RNA-binding interface comprises basic residues from zinc finger 1 and hydrophobic residues from β-sheet and zinc finger 2. Further we show that the linker between the ZFD and MTD of METTL3 is flexible but partially folded, which may permit the cooperation between the two domains during catalysis. Together, the structural characterization of METTL3 ZFD paves the way to elucidate the atomic details of the entire process of RNA mA modification.