Structural basis of photosensitivity in a bacterial light-oxygen-voltage/ helix-turn-helix (LOV-HTH) DNA-binding protein

Abigail I. Nash, Reginald McNulty, Mary Elizabeth Shillito, Trevor E. Swartz, Roberto A. Bogomolni, Hartmut Luecke, Kevin H. Gardner

Research output: Contribution to journalArticlepeer-review

142 Scopus citations


Light-oxygen-voltage (LOV) domains are blue light-activated signaling modules integral to a wide range of photosensory proteins. Upon illumination, LOV domains form internal protein-flavin adducts that generate conformational changes which control effector function. Here we advance our understanding of LOV regulation with structural, biophysical, and biochemical studies of EL222, a light-regulated DNA-binding protein. The dark-state crystal structure reveals interactions between the EL222 LOV and helix-turn-helix domains that we show inhibit DNA binding. Solution biophysical data indicate that illumination breaks these interactions, freeing the LOV and helix-turn-helix domains of each other. This conformational change has a key functional effect, allowing EL222 to bind DNA in a light-dependent manner. Our data reveal a conserved signaling mechanism among diverse LOV-containing proteins, where light-induced conformational changes trigger activation via a conserved interaction surface.

Original languageEnglish (US)
Pages (from-to)9449-9454
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number23
StatePublished - Jun 7 2011


  • Allosteric regulation
  • PER-ARNT-SIM domain
  • Photosensing

ASJC Scopus subject areas

  • General


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