Peer-reviewed research.

First Author · bioRxiv · 2025 · Preprint

The dramatic impact of the PER–DBT interaction on circadian timekeeping and temperature compensation

E. Nicholas Petersen, C. Sullivan, H. Ludewig, D. Kern, M. Rosbash

The circadian clock relies on phosphorylation-dependent timers to dictate period length and ensure temperature compensation. Using AlphaFold2-multimer, we predicted the interaction interface between PERIOD (PER) and DOUBLETIME (DBT/CK1). Structure-guided point mutations designed at this interface produced Drosophila circadian periods exceeding 48 hours and revealed a mechanism of temperature compensation driven by PER-DBT interface dynamics.

• AlphaFold2 prediction of the PER-DBT complex interface verified by structure-guided mutagenesis
• Created charge-swap rescue mutants (E621K/K789E) supporting a critical salt bridge
• Discovered the longest circadian period mutants on record (>35 hours)
• Characterized a structural mechanism underlying temperature compensation

First Author · eLife · 2023

Mechanical activation of TWIK-related potassium channel by nanoscopic movement and rapid second messenger signaling

E. Nicholas Petersen, M. A. Pavel, S. S. Hansen, M. Gudheti, H. Wang, Z. Yuan, K. R. Murphy, W. W. Ja, H. A. Ferris, E. M. Jorgensen, S. B. Hansen

Mechanosensory ion channels like TREK-1 respond to physical force, but the molecular events upstream of gating remain debated. Mechanical shear stress moves phospholipase D (PLD2) into ordered lipid domains (GM1 rafts), where it produces localized phosphatidic acid (PA) that gates TREK-1 channels. Super-resolution dSTORM in intact Drosophila brains and temperature-clamped shear fixation showed that this raft-mediated pathway controls behavioral mechanosensation in vivo.

• Linked force-induced TREK-1 activation to PLD2 translocation rather than direct bilayer tension alone
• Developed rapid temperature-controlled shear fixation (<10s) at 37 °C
• Demonstrated dSTORM super-resolution imaging in intact Drosophila brain tissue
• Established behavioral mechanosensation defect in PLD-null Drosophila models

First Author · BBA – Biomembranes · 2020

Disruption of palmitate-mediated localization; a shared pathway of force and anesthetic activation of TREK-1 channels

E. Nicholas Petersen, M. A. Pavel, H. Wang, S. B. Hansen

Post-translational palmitoylation targets proteins to ordered membrane nanodomains. We investigated how general anesthetics and mechanical shear disrupt palmitate-dependent localization of TREK-1 channels. Both physical force and inhaled anesthetics displace TREK-1 from lipid rafts into PIP2-rich domains, establishing palmitate-mediated localization disruption as a unified molecular mechanism for channel activation.

• Identified palmitate-mediated nanodomain localization as a shared target for force and anesthetics
• Methodological critique of probe-valency and fixation artifacts in super-resolution imaging
• Mapped spatial translocation of K2P channels between lipid rafts and PIP2 signaling hubs
• Provided a structural basis for two-pore domain potassium channel gating

First Author · bioRxiv · 2019 · Preprint

Measuring anesthetic resistance in Drosophila by VAAPR

E. Nicholas Petersen, C. R. Clowes, S. B. Hansen

Detailed methodological design and validation of the VAAPR rig (Volatile Anesthetic Administration in Parallel in Drosophila). Describes chamber engineering, vapor flow control, automated machine-vision tracking, and statistical protocol for T50 anesthetic dose-response determination.

• First author method paper establishing the VAAPR behavioral testing apparatus
• Engineered multi-chamber vapor distribution manifold for quantitative pharmacology
• Provided open protocol for high-throughput Drosophila neuropharmacology

Co-First Author · Journal of Molecular Biology · 2019

A Molecular Target for an Alcohol Chain-Length Cutoff

H.-W. Chung*, E. Nicholas Petersen*, C. Cabanos, K. R. Murphy, M. A. Pavel, A. S. Hansen, W. W. Ja, S. B. Hansen (*co-first authors)

Long-chain n-alcohols exhibit a well-known ‘cutoff effect’ where anesthetic and intoxicating potency abruptly disappears past a specific carbon chain length. We synthesized homologous primary alcohols (C1–C16) and demonstrated that PLD2 enzyme inhibition mirrors the exact physical cutoff observed in fly sedation behavior, identifying PLD2 as the molecular target of the alcohol cutoff.

• Identified PLD2 as the molecular target explaining the alcohol chain-length cutoff
• Co-first author on biochemical SAR and fly behavioral sedation assays
• Purified recombinant PLD2 from yeast and reconstituted into proteoliposomes
• Demonstrated physical cutoff transition between C10 and C12 primary alcohols

First Author · Nature Communications · 2016

Kinetic disruption of lipid rafts is a mechanosensor for phospholipase D

E. Nicholas Petersen, H.-W. Chung, A. Nayebosadri, S. B. Hansen

We introduced a kinetic non-tension model of mechanotransduction. Mechanical shear stress disrupted ordered GM1 lipid rafts, mixing substrate and enzyme and activating PLD2. Live-cell 3D-dSTORM captured these changes at sub-second reconstructed frame rates.

• First-author publication in Nature Communications
• Discovered kinetic (non-tension) lipid raft disruption mechanism for mechanosensation
• Developed sub-second reconstructed live-cell 3D-dSTORM imaging (~250 ms frame rate)
• Invented live-cell real-time PLD activity assay under fluid shear stress

Co-Author · PNAS · 2020

Studies on the mechanism of general anesthesia

M. A. Pavel, E. Nicholas Petersen, H. Wang, R. A. Lerner, S. B. Hansen

For over 120 years, the Meyer-Overton correlation linked general anesthetic potency to lipid solubility, yet direct membrane-mediated gating mechanisms remained unproven. We show that inhaled anesthetics disrupt ordered GM1 lipid rafts, releasing PLD2 to generate PA and activate TREK-1 channels. In Drosophila, knocking out PLD2 renders flies resistant to volatile anesthesia, validating a membrane-mediated mechanism in whole animals.

• Linked anesthetic disruption of GM1 lipid rafts to PLD2 activation and TREK-1 gating
• Demonstrated inhaled anesthetics trigger PLD2 catalytic activation in live cells and fly brains
• Used a custom VAAPR assay rig to quantify in vivo anesthetic resistance in Drosophila
• Showed that PLD2 knockout flies resist volatile anesthesia

Co-Author · Anesthesia & Analgesia · 2019

Polymodal Mechanism for TWIK-Related K+ Channel Inhibition by Local Anesthetic

M. A. Pavel, H.-W. Chung, E. Nicholas Petersen, S. B. Hansen

Investigated how charged local anesthetics (e.g. tetracaine, bupivacaine) inhibit TREK-1 potassium channels via direct pore block versus membrane domain perturbation.

• Characterized dual mechanism of local anesthetic inhibition on two-pore domain potassium channels
• Applied super-resolution SMLM to map local anesthetic-induced channel localization changes

Co-Author · PNAS · 2013

Nascent peptides that block protein synthesis in bacteria

C. J. Woolstenhulme, S. Parajuli, D. W. Healey, D. P. Valverde, E. Nicholas Petersen, A. L. Starosta, N. R. Guydosh, W. E. Johnson, D. N. Wilson, A. R. Buskirk

Identified specific nascent peptide motifs that stall translation by interacting with the E. coli ribosome exit tunnel using yeast two-hybrid selection and radiolabeled 35S pulse-chase kinetics.

• Co-author on PNAS study identifying bacterial ribosome stalling peptides
• Executed genetic selections and 35S radiolabeled pulse-chase translation assays

Co-Author · PNAS · 2020

Reply to van Swinderen and Hines: Drosophila model establishes the lipid membrane as a target of anesthetics

S. B. Hansen, R. A. Lerner, M. A. Pavel, E. Nicholas Petersen

• Defended lipid membrane anesthetic mechanism against alternative neuronal models
• Re-affirmed quantitative T50 behavioral assays in genetic knockout flies