title: Exploration of binding affinity and selectivity of brucine with G-quadruplex in the c-myb proto-oncogene by electrospray ionization mass spectrometry.
abstract: BACKGROUND
  The c-myb gene is a potential therapeutic target for human tumors and leukemias. Active ingredients from natural products may be used as drugs in chemotherapy for human cancers. Here, electrospray ionization mass spectrometry (ESI-MS) was used to probe the formation and recognition of the G-quadruplex structure from the G-rich sequence that is found in the c-myb gene promoter, 5'-GGGCTGGGCTGGGCGGGG-3'. The aim of our study is to evaluate a potential binder for the c-myb gene from natural products, and thereby to modulate c-myb gene expression.
  
  
  METHODS
  ESI-MS, as an effective method, was utilized not only to characterize the formation of the G-quadruplex in the c-myb oncogene, but also as a tool to probe the binding characteristics of alkaloid molecules with the target G-quadruplex DNA.
  
  
  RESULTS
  ESI-MS results with the support of circular dichroism (CD) spectra demonstrated the formation of an intramolecular parallel-stranded G-quadruplex in the c-myb oncogene promoter. A screening of six alkaloid molecules showed that brucine (P1) had a strong binding affinity to the c-myb G-quadruplex DNA. It is notable that P1 can bind selectively to the c-myb G-quadruplex with respect to duplex DNAs, as well as to G-quadruplexes in other types of gene sequences. According to ESI-MS results, in which the stability was tested by capillary heating and collision-induced dissociation, the binding of P1 could thermally stabilize the c-myb G-quadruplex DNA.
  
  
  CONCLUSIONS
  In this work, brucine (P1), an alkaloid molecule, has been found to bind to the intramolecular parallel G-quadruplex in the c-myb oncogene promoter with high affinity and selectivity, and could thermally stabilize the c-myb G-quadruplex DNA, indicating that the binding of P1 has the potential to modulate c-myb gene expression. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.|National and Local Joint Engineering Research Center of Biomedical Functional Materials, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Hai
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
authors.forename: Gu
authors.initials: G
authors.lastname: Yuan
mesh_terms: D001665:Binding Sites; D054856:G-Quadruplexes; D006801:Humans; D007700:Kinetics; D011401:Promoter Regions, Genetic; D000090063:Proto-Oncogene Mas; D020598:Proto-Oncogene Proteins c-myb / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013331:Strychnine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
chemical_list: C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D020598:Proto-Oncogene Proteins c-myb; C083806:brucine; D013331:Strychnine