Application of ring-closing metathesis macrocyclization to the development of Tsg101-binding antagonists

Abstract

HIV-1 viral budding involves binding of the viral Gag p6 protein to the ubiquitin E2 variant domain of the human tumor susceptibility gene 101 protein (Tsg101). Recognition of p6 by Tsg101 is mediated in part by a proline-rich motif that contains the sequence "Pro-Thr-Ala-Pro" ("PTAP"). Using the p6-derived 9-mer sequence "PEPTAPPEE", we had previously improved peptide binding affinity by employing N-alkylglycine ("peptoid") residues. The current study applies ring-closing metathesis macrocyclization strategies to Tsg101-binding peptide-peptoid hybrids as an approach to stabilize binding conformations and to observe the effects of such macrocyclization on Tsg101-binding affinity and bioavailability. Viral release is a necessary component of HIV-1 replication. To be an efficient process, viral budding relies on recruitment of the ubiquitin E2 variant (UEV) domain of the human tumor susceptibility gene 101 protein (Tsg101) by major structural proteins of HIV-1.1 , 2 This entails the direct interaction of the Tsg101 UEV domain with a proline rich motif (PRM) within the viral Gag p6 protein that contains a conserved sequence, Pro-Thr/Ser-Ala-Pro ["P(T/S)AP"]. 3 , 4 Over-expression of the Tsg101 UEV inhibits virus release by interfering with processing of the p6 domains and this effect is abrogated by mutation within the P(T/S)AP binding site. In theory, blocking this critical Tsg101-p6 interaction could prevent viral budding and provide a basis for new targeted antiretroviral therapies.5 , 6 This is supported by the recent finding that inhibition of HIV budding can be achieved by cyclic peptides that interfere with Tsg101-Gag interactions.7In an effort to develop Tsg101-binding inhibitors using the reported p6-derived 9-mer wildtype (WT) sequence "P 1 E 2 P 3 T 4 A 5 P 6 P 7 E 8 E 9 ," we had previously improved Tsg101-binding affinity by applying hydrazone-and hydrazide-library techniques.8 We also reported an oxime-*Corresponding authors. liuf@ncifcrf.gov (F. Liu); tburke@helix.nih.gov (T.R. Burke).. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Supporting information Supporting information associated with this article, including reaction yields and analytical data for products 8a -8g, mass spectral data for peptides and peptide -peptoid hybrids and Tsg101 -binding affinities can be found, in the online version, at doi:10.1016/j.bmcl.2009.10.105. NIH Public Access Author ManuscriptBioorg Med Chem Lett. Author manuscript; available in PMC 2011 January 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript based post solid-phase diversification...

A Theoretical Investigation into the Luminescent Properties of d8‐Transition‐Metal Complexes with Tetradentate Schiff Base Ligands

“…However, macrocycles based on α‐amino acids connected with other organic linkers7–13 are also included in this family. Ring‐closing olefin metathesis has played a crucial role in the preparation of a variety of cyclic peptides, useful in medicinal chemistry,14 ranging from simple di‐,15–23 tri‐,24–28 and tetrapeptides29–33 to macrocycles 34–40. In addition, some cyclic peptides are assemblies of α‐amino acids with β‐amino acids and other building blocks 41–43.…”

HIV Type 1 Gag as a Target for Antiviral Therapy

“…212,213 Finally, the binding conformations were stabilized and cellular uptake was increased by peptide circularization. 214 Efforts are underway in our laboratory to test these peptoids for their ability to inhibit HIV-1 budding in cell-based assays. In an independent study, Tavassoli et al designed a bacterial reverse two-hybrid system (RTHS) to identify inhibitors of the p6-Tsg101 interaction.…”

The Synthesis of Macrocycles for Drug Discovery

“…The optimized process has been subsequently applied to the preparation of modified macrolide structures. 243 In another example involving nickel, in this case as a co-catalyst, the use of mixtures of PEG 400 /MeOH as solvent enabled an intramolecular Glaser-Hay coupling 244 of simple terminal alkynes (140) to form 14-to 27-membered macrocyclic diynes (141,Scheme 11.18) to be conducted at comparatively high concentrations (up to 0.1 M). This was attributed to the aggregation properties of the PEG preferentially solubilizing the organic substrates, thus creating a phase separation from the copper-nickel catalyst system.…”