Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Poster Abstracts

12-POS Board 13 STRUCTURAL BASIS OF BRYOSTATIN-1 INTERACTIONS WITH PERIPHERAL MEMBRANE BINDING C1 DOMAINS OF PROTEIN KINASE C Sachin S Katti 1 ; Tien Nguyen 1 ; Lokendra Poudel; Savana M Green 1 ; Vytas A Bankaitis 1 ; Tatyana I Igumenova 1,2 ; 1 Texas A&M University, Cell Biology & Genetics, College Station, TX, USA 2 Texas A&M University, Biochemistry & Biophysics, College Station, TX, USA Several isoforms of Protein Kinase C (PKC) family are lipid-activated Ser/Thr kinases that translate GPCR-mediated external stimuli into intracellular signaling events. Pharmacological modulation of PKC activity at membranes holds significant promise in the treatment of various cancers and neurodegenerative disorders. To that end, several classes of lipophilic compounds have been identified that target the diacylglycerol (DAG)-dependent membrane-anchoring modules of PKC regulatory region, the conserved homology 1 domains (C1 domains). Among the DAG-mimicking macrocyclic lactones, Bryostatin-1 has gained considerable traction due to its antineoplastic, neuroprotective, and anti-retroviral activities observed in clinical studies. However, the mechanism of Bryostatin-1 driven PKC activation at the membrane remains poorly characterized. In this work, we integrate solution NMR spectroscopy, atomistic molecular dynamics simulations, and cellular membrane translocation assays to describe the interactions of Bryostatin-1 with the DAG-sensitive C1 domains of PKC and ε isoforms. NMR of the Bryostatin-1-complexed C1 domain in lipid bicelles identified the protein residues that undergo membrane insertion upon complex formation. Additional information on the geometry of protein-membrane interactions and the isoform-specific dynamics of protein and Bryostatin-1 was obtained from atomistic MD simulations. Consistent with those findings, in-cell imaging experiments show clear isoform-specific differences in Bryostatin-1-induced membrane translocation properties. Taken together, this integrative approach offers new insights into future design of effective Bryostatin analogs.

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