Synthesis and single-molecule imaging reveal stereospecific enhancement of binding kinetics by the antitumor eEF1A antagonist SR-A3

Ternatin-family cyclic peptides inhibit protein synthesis by targeting the eukaryotic elongation factor-1α (eEF1A). A potentially related cytotoxic natural product ("A3") was isolated from Aspergillus, but only 4 of its 11 stereocenters could be assigned. Here, we synthesized SR-A3 and SS-...

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Published inbioRxiv
Main Authors Wang, Haoyuan, Yang, Haojun, Holm, Mikael, Oltion, Keely, Harrison, Tom, Amjad Ayad Qatran Al-Khdhairawi, Weber, Jean-Frederic F, Blanchard, Scott, Ruggero, Davide, Taunton, Jack
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 03.02.2022
Subjects
Cell proliferation
Elongation
Hydroxylation
Leucine
Natural products
Patent applications
Peptides
Protein biosynthesis
Stereochemistry
Stereoisomers
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Summary:Ternatin-family cyclic peptides inhibit protein synthesis by targeting the eukaryotic elongation factor-1α (eEF1A). A potentially related cytotoxic natural product ("A3") was isolated from Aspergillus, but only 4 of its 11 stereocenters could be assigned. Here, we synthesized SR-A3 and SS-A3 -- two out of 128 possible A3 epimers -- and discovered that synthetic SR-A3 is indistinguishable from naturally derived A3. Relative to SS-A3, SR-A3 exhibits enhanced residence time and rebinding kinetics, as revealed by single-molecule fluorescence imaging of elongation reactions catalyzed by eEF1A in vitro. Increased residence time -- stereospecifically conferred by the unique β-hydroxyl in SR-A3 -- was also observed in cells. Consistent with its prolonged duration of action, thrice-weekly dosing with SR-A3 led to dramatically increased survival in an aggressive Myc-driven mouse lymphoma model. Our results demonstrate the potential of SR-A3 as a cancer therapeutic and exemplify an evolutionary mechanism for enhancing cyclic peptide binding kinetics via stereospecific side-chain hydroxylation. Competing Interest Statement The University of California, San Francisco has filed a provisional patent application based on part of this work; J.T., D.R., H.Y.W., H.Y., and K.O. are listed as inventors. Footnotes * We added new results (e.g. smFRET and mouse tumor model) in this version.
DOI:10.1101/2020.10.06.325498