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Issue 7, 2013
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Signaling mechanisms of LOV domains: new insights from molecular dynamics studies

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Abstract

Phototropins are one of several classes of photoreceptors used by plants and algae to respond to light. These proteins contain flavin-binding LOV (Light-Oxygen-Voltage) domains that form covalent cysteine-flavin adducts upon exposure to blue light, leading to the enhancement of phototropin kinase activity. Several lines of evidence suggest that adduct formation in the phototropin LOV2 domains leads to the dissociation of an alpha helix (Jα) from these domains as part of the light-induced activation process. However, crystal structures of LOV domains both in the presence and absence of the Jα helix show very few differences between dark and illuminated states, and thus the precise mechanism through which adduct formation triggers helical dissociation remains poorly understood. Using Avena sativa phototropin 1 LOV2 as a model system, we have studied the interactions of the LOV domain core with the Jα helix through a series of equilibrium molecular dynamics simulations. Here we show that conformational transitions of a conserved glutamine residue in the flavin binding pocket are coupled to altered dynamics of the Jα helix both through a shift in dynamics of the main β-sheet of the LOV domain core and through a secondary pathway involving the N-terminal A′α helix.

Graphical abstract: Signaling mechanisms of LOV domains: new insights from molecular dynamics studies

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Publication details

The article was received on 25 Nov 2012, accepted on 04 Feb 2013 and first published on 05 Feb 2013


Article type: Paper
DOI: 10.1039/C3PP25400C
Citation: Photochem. Photobiol. Sci., 2013,12, 1158-1170
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    Signaling mechanisms of LOV domains: new insights from molecular dynamics studies

    P. L. Freddolino, K. H. Gardner and K. Schulten, Photochem. Photobiol. Sci., 2013, 12, 1158
    DOI: 10.1039/C3PP25400C

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