Molecule of the Month: Phototropin
Phototrophins sense the level of blue light, allowing plants to respond to changing environmental conditions
Seeing the Light
Made with LOV
Sending the Signal
Exploring the Structure
Phototropin LOV2 Domain (PDB entries 1g28 and 1jnu)
Scientists have solved structures of the phototropin LOV domains, as well as other blue-light sensing proteins, in both the dark and after they absorb light. In phototropin, the photo-activated flavin reacts with a nearby cysteine amino acid, forming a covalent bond. This distorts the flavin ring, and also distorts the surrounding protein. The two structures are available in PDB entries 1g28 and 1jnu . Click on the image to explore these structures in an interactive JSmol.
Topics for Further Discussion
- There are many other structures for proteins that sense blue light. To see other proteins like phototropin, try searching the PDB for "LOV," and to see other types of proteins, search for "cryptochrome" or "BLUF."
- Flavins are also used as electron-carrying cofactors in many enzymatic reactions. You can search for "FAD" to find examples in the PDB.
- You can use the "Protein Feature View" to see how the different domains of phototropin fit together, for instance, in the view of Arabidopsis phototropin.
March 2015, David Goodsellhttp://doi.org/10.2210/rcsb_pdb/mom_2015_3