title: Signals of LOV1: a computer simulation study on the wildtype LOV1-domain of Chlamydomonas reinhardtii and its mutants.
abstract: Phototropins are photoreceptors regulating the blue-light response in plants and bacteria. They consist of two LOV (light oxygen voltage sensitive) domains each containing a non-covalently bound flavin-mononucleotide (FMN) chromophore, which are connected to a serine/threonine-kinase. Upon illumination, the LOV-domains undergo conformational changes, triggering a signal cascade in the organism through kinase activation. Here, we present results from molecular dynamics simulations in which we investigate the signal transduction pathway of the wildtype LOV1-domain of Chlamydomonas reinhardtii and a methyl-mercaptan (MM) adduct of its Cys57Gly-mutant at the molecular level. In particular, we analyzed the effect of covalent-bond formation between the reactive cysteine Cys57 and the FMN-reaction center, as well as the subsequent charge redistribution, on the spatio-dynamical behavior of the LOV1-domain. We compare the calculation results with experimental data and demonstrate that these adduct state characteristics have an important influence on the response of this photosensor. The light-induced changes implicate primarily an alteration of the surface charge distribution through rearrangement of the highly flexible Cα-, Dα- and Eα-helices including the Glu51-Lys91-salt bridge on the hydrophilic side of the protein domain and a β-sheet tightening process via coupling of the Aβ- and Bβ-strands. Our findings confirm the aptitude of the LOV1-domain to function as a dimerization partner, allowing the green alga to adapt its reproduction and growth speed to the environmental conditions.
authors.affiliation: Department of Chemistry and Pharmacy, Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040 Regensburg, Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Peter
authors.forename: Bernhard
authors.initials: B
authors.lastname: Dick
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Baeurle
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D005486:Flavin Mononucleotide / Q000737:chemistry / Q000378:metabolism; D005420:Flavoproteins / Q000737:chemistry / Q000378:metabolism; D055537:Light Signal Transduction; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D010777:Photochemistry / Q000379:methods; D056949:Phototropins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D005420:Flavoproteins; D050505:Mutant Proteins; D056949:Phototropins; D005486:Flavin Mononucleotide; D003545:Cysteine