Dataset Information

Dual-Resolving of Positional and Geometric Isomerism of C=Cs via Bifunctional Visible-light-activated Photocycloaddition-Photoisomerization Reaction System

ABSTRACT: The biological functions of lipids largely depend on their chemicalspatial structures. The position and configuration of C=C bonds are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we developed a bifunctional visible-light-activated photocycloaddition-photoisomerization reaction system, which enabled the dual-resolving of the positional and geometric isomerism of C=C bonds in lipids when combined with liquid chromatographic mass spectrometry. The dual-pathway reaction mechanism was demonstrated by experiments and density functional theory calculations. Based on this bifunctional reaction system, a workflow of deep structural lipidomics was established, and allowed the revealing of unique patterns of cis-trans-isomers in bacteria, as well as the tracking of C=C positional isomers changes in mouse brain ischemia. This study not only offers a powerful tool for deep lipid structural biology, but also provides a new paradigm for developing the multifunctional visible-light-induced reaction.

ORGANISM(S): Homo Sapiens Arabidopsis Thaliana

SUBMITTER: Suming Chen

PROVIDER: PXD031819 | iProX | Sat Feb 19 00:00:00 GMT 2022

REPOSITORIES: iProX

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Dual-resolving of positional and geometric isomers of C=C bonds via bifunctional photocycloaddition-photoisomerization reaction system.

Feng Guifang G Gao Ming M Wang Liwei L Chen Jiayi J Hou Menglu M Wan Qiongqiong Q Lin Yun Y Xu Guoyong G Qi Xiaotian X Chen Suming S

Nature communications 20220512 1

The biological functions of lipids largely depend on their chemical structures. The position and configuration of C=C bonds are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a bifunctional visible-light-activated photocycloaddition-photoisomerization reaction system, which enables the dual-resolving of the positional and geometric isomerism of C=C bonds in lipids w ...[more]

PMID: 35550511

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Project description:Proteolysis Targeting Chimeras (PROTACs) hijack the ubiquitin proteasome system to ubiquitinate target proteins, targeting them for degradation by the proteasome. An understudied process that is essential to the PROTAC mechanism of action is ubiquitination of the target protein and ubiquitin (Ub) chain elongation. These phenomena are difficult to study structurally due the instability of the thioester-linked ubiquitin (Ub)-E2 conjugates that rapidly discharges ubiquitin onto the target protein, catalysed by a Cullin-RING E3 Ubiquitin Ligase (CRL). To overcome this, stable isopeptide-linked Ub-E2 conjugates were generated using an active site mutant of the chain elongation E2 enzyme UBE2R1 and used in structural studies of a model PROTAC system consisting of neddylated CRL2VHL, MZ1 and BRD4(BD2)-Ub. This approach resulted in multiple novel cryo-EM structures of the active CRL in complex with the model substrate and MZ1. To validate the conformation of the Ub-Ube2R1-Rbx1 within these structures, a ubiquitin-directed photoreactive probe (UDPRP) was designed. The UDPRP consists of a stable-isopeptide linked Ub-Ube2R1 conjugate as used in the except the ubiquitin is site-specifically labelled with the photocrosslinker, N-maleimido-diazirine. The diazirine based photocrosslinker is site-specifically labelled to ubiquitin through cysteine-maleimide chemistry. Upon exposure to UV light (365 nM) forms a reactive carbene intermediate which either rapidly inserts into X-H bonds (including O-H, N-H, S-H and C-H bonds) and can therefore covalently trap proteins in close-proximity. In a photocrosslinking assay containing neddylated-CRL2VHL and the UDPRP. The UDPRP crosslinked to Rbx1, the RING portion of the multi-subunit CRL E3. To map the site of crosslinking the photo-crosslinked product was excised from the gel and analysed by mass-spectrometry. Four inter-protein crosslinked peptides from ubiquitin-rbx1 were detected, with an andromeda score >90, linking ubiquitin E34C to the last three C-terminal residues of Rbx1.

Dataset Information

Dual-Resolving of Positional and Geometric Isomerism of C=Cs via Bifunctional Visible-light-activated Photocycloaddition-Photoisomerization Reaction System

Publications

Dual-resolving of positional and geometric isomers of C=C bonds via bifunctional photocycloaddition-photoisomerization reaction system.

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