PDBsum entry: 1g28

Signaling protein, electron transport

PDB-id: 1g28

Asymmetric unit

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Description

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References

PROCHECK

Protein chains

104 a.a. *

Ligands

FMN ×4

Waters ×51

* Residue conservation analysis

Tools

Clefts Calculation

Biological unit*, dimer
(*as deduced by PQS)

PDB id:

1g28

Name:

Signaling protein, electron transport

Title:

Structure of a flavin-binding domain, lov2, from the chimeric phytochrome/phototropin photoreceptor phy3

Structure:

Phy3 protein. Chain: a, b, c, d. Fragment: fmn-binding domain of chimeric phytochrome/phototropin photoreceptor, lov3. Engineered: yes

Source:

Adiantum capillus-veneris. Organism_taxid: 13818. Gene: phy3. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Biological unit:

Dimer (from PQS)

UniProt:

Chains A, B, C, D: Q9ZWQ6 (Q9ZWQ6_ADICA)

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

1465 a.a.

Struc:

104 a.a.

Key:	PfamA domain
Secondary structure	CATH domain

Resolution:

2.73Å

R-factor:

0.247

R-free:

0.272

Authors:

S.Crosson,K.Moffat

Key ref:

S.Crosson and K.Moffat (2001). Structure of a flavin-binding plant photoreceptor domain: insights into light-mediated signal transduction.. Proc Natl Acad Sci U S A, 98, 2995-3000. [PubMed id: 11248020] [DOI: 10.1073/pnas.051520298]

Date:

17-Oct-00

Release date:

21-Mar-01

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Surface

Key reference

DOI no: 10.1073/pnas.051520298

Proc Natl Acad Sci U S A 98:2995-3000 (2001)

PubMed id: 11248020

Structure of a flavin-binding plant photoreceptor domain: insights into light-mediated signal transduction.

S.Crosson, K.Moffat.

ABSTRACT

Phototropin, a major blue-light receptor for phototropism in seed plants, exhibits blue-light-dependent autophosphorylation and contains two light, oxygen, or voltage (LOV) domains and a serine/threonine kinase domain. The LOV domains share homology with the PER-ARNT-SIM (PAS) superfamily, a diverse group of sensor proteins. Each LOV domain noncovalently binds a single FMN molecule and exhibits reversible photochemistry in vitro when expressed separately or in tandem. We have determined the crystal structure of the LOV2 domain from the phototropin segment of the chimeric fern photoreceptor phy3 to 2.7-A resolution. The structure constitutes an FMN-binding fold that reveals how the flavin cofactor is embedded in the protein. The single LOV2 cysteine residue is located 4.2 A from flavin atom C(4a), consistent with a model in which absorption of blue light induces formation of a covalent cysteinyl-C(4a) adduct. Residues that interact with FMN in the phototropin segment of the chimeric fern photoreceptor (phy3) LOV2 are conserved in LOV domains from phototropin of other plant species and from three proteins involved in the regulation of circadian rhythms in Arabidopsis and Neurospora. This conservation suggests that these domains exhibit the same overall fold and share a common mechanism for flavin binding and light-induced signaling.

Selected figure(s)

Figure 2.
Fig. 2. Chromophore of phy3 LOV2. (A) Simulated-annealing omit map of FMN from one of the four monomers in the asymmetric unit. The map is contoured at ±3.5 (blue) and ±10 (yellow), in which is the rms-deviation value of the electron density. Electron density distinguishes the dimethylbenzene and pyrimidine moieties of the isoalloaxazine ring and shows a +10 feature over the terminal phosphate. (B) Stereo diagram of FMN-protein interactions. All residues and waters that hydrogen bond to or form van der Waals contact with FMN are shown. Hydrogen bonds are indicated by the dotted blue lines using a 2.6- to 3.5-Å range for hydrogen bonding. Atoms are colored as in Fig. 1 with the addition of sulfur as yellow, water molecules as light blue, and C(4a) of the isoalloxazine ring as pink.

Figure 5.
Fig. 5. Proposed schematic mechanism for cysteine-C(4a) covalent adduct formation in response to light absorption by the LOV domain (see text).

Figures were selected by an automated process.