PXD071945

PXD071945 is an original dataset announced via ProteomeXchange.

Title	Total Synthesis and Biological Evaluation of Leptosphaerone B and Derivatives of Microketide A
Description	Microketide A and B are fungal polyketides reported to display potent activity against Gram-negative pathogens, yet the complex and low yielding isolation from fungal cultures and a lack of synthetic access have prevented detailed investigation of their mode of action and structure-activity relationship. Here, we report the first total synthesis of two close analogues of microketide A, dihydro-MikA, and 11-deoxy-MikA as well as of racemic leptosphaerone B, another member of this cyclohexenone-based natural product family. Our route features a modular assembly of highly functionalized fragments and enables divergent access to analogs through selective dihydroxylation and late-stage fragment fusion. Despite extensive exploration of multiple C–C bond-forming strategies, unfavorable sterics and competing eliminations prevented successful connection of the fully elaborated fragments required for microketide A. The synthesized compounds leptosphaerone B, dihydro-MikA, and 11-deoxy-MikA were evaluated for antibacterial activity and human cytotoxicity but showed no effects up to 200 μM. Competitive residue-specific chemoproteomics and in vitro nucleophile-trapping experiments further revealed no covalent protein engagement, indicating that these scaffolds are intrinsically weak electrophiles and unlikely to act through Michael addition. Together, our findings suggest that microketide A possesses a restrictive structure–activity relationship, in which even subtle modifications abolish biological function. The synthetic strategy described herein provides a robust platform for exploiting alternative modifications for in-depth structure activity relationship studies assessing the biological potential of this natural product.
HostingRepository	PRIDE
AnnounceDate	2026-03-01
AnnouncementXML	Submission_2026-02-28_16:46:12.833.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Martin Frederik Köllen
SpeciesList	scientific name: Escherichia coli (strain K12); NCBI TaxID: NEWT:83333; scientific name: Staphylococcus aureus subsp. aureus NCTC 8325; NCBI TaxID: NEWT:93061;
ModificationList	No PTMs are included in the dataset
Instrument	Orbitrap Eclipse; timsTOF Pro

Revision	Datetime	Status	ChangeLog Entry
0	2025-12-13 02:50:34	ID requested
⏵ 1	2026-02-28 16:46:13	announced

10.1021/ACS.JNATPROD.5C01581;

submitter keyword: Full proteome, Orbitrap Eclipse, timsTOF, S. aureus,E. coli, isoDTB-ABPP

Stephan Axel Sieber
contact affiliation	TUM School of Natural Sciences, Department of Bioscience, Center for Functional Protein Assemblies (CPA), Chair of Organic Chemistry II, Technical University of Munich, 85748 Garching bei München, Germany
contact email	stephan.sieber@tum.de
lab head
Martin Frederik Köllen
contact affiliation	TUM School of Natural Sciences, Department of Bioscience, Center for Functional Protein Assemblies (CPA), Chair of Organic Chemistry II, Technical University of Munich, 85748 Garching bei München, Germany
contact email	martin.koellen@tum.de
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD071945
     1. Label: PRIDE project
     2. Name: Total Synthesis and Biological Evaluation of Leptosphaerone B and Derivatives of Microketide A