The amino-terminal helix modulates light-activated conformational changes in AsLOV2

Josiah P. Zayner, Chloe Antoniou, Tobin R. Sosnick

Research output: Contribution to journalArticlepeer-review


The mechanism of light-triggered conformational change and signaling in light-oxygen-voltage (LOV) domains remains elusive in spite of extensive investigation and their use in optogenetic studies. The LOV2 domain of Avena sativa phototropin 1 (AsLOV2), a member of the Per-Arnt-Sim (PAS) family, contains a flavin mononucleotide chromophore that forms a covalent bond with a cysteine upon illumination. This event leads to the release of the carboxy-terminal Jα helix, the biological output signal. Using mutational analysis, circular dichroism, and NMR, we find that the largely ignored amino-terminal helix is a control element in AsLOV2's light-activated conformational change. We further identify a direct amino-to-carboxy-terminal "input-output" signaling pathway. These findings provide a framework to rationalize the LOV domain architecture, as well as the signaling mechanisms in both isolated and tandem arrangements of PAS domains. This knowledge can be applied in engineering LOV-based photoswitches, opening up new design strategies and improving existing ones.

Original languageEnglish
Pages (from-to)61-74
Number of pages14
JournalJournal of Molecular Biology
Issue number1-2
Publication statusPublished - 25 May 2012


  • LOV domains
  • NMR
  • PAS domains


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