How mithramycin stereochemistry dictates its structure and DNA binding function.
MEDCHEMCOMM 2019;
10:735-741. [PMID:
31191864 DOI:
10.1039/c9md00100j]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/28/2019] [Indexed: 12/16/2022]
Abstract
An aureolic acid natural product mithramycin (MTM) has been known for its potent antineoplastic properties. MTM inhibits cell growth by binding in the minor groove of double-stranded DNA as a dimer, in which the two molecules of MTM are coordinated to each other through a divalent metal ion. A crystal structure of an MTM analogue, MTM SA-Phe, in the active metal ion-coordinated dimeric form demonstrates how the stereochemical features of MTM define the helicity of the dimeric scaffold for its binding to a right-handed DNA double helix. We also show crystallographically and biochemically that MTM, but not MTM SA-Phe, can be inactivated by boric acid through formation of a large macrocyclic species, in which two molecules of MTM are crosslinked to each other through 3-side chain-boron-sugar intermolecular bonds. We discuss these structural and biochemical properties in the context of MTM biosynthesis and the design of MTM analogues as anticancer therapeutics.
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