Abstract
LOV domains form subfamily of a PAS domain in the Light-Oxygen-Voltage sensing proteins. One of the major LOV proteins, phototropin (phot) has two LOV domains named LOV1 and LOV2. Despite the almost identical crystal structures, LOV1 and LOV2 have distinct functions. LOV2 plays significant roles in the photoregulation, however, LOV1 doesn't. One of the important roles of LOV1 is thought to be a dimerization site. Oligomeric structures, therefore, of LOV domains in Arabidopsis phot and their light-induced changes were studied by using a chemical cross-linking technique. Arabidopsis has two phots, phot1 and phot2, a broad-range and a strong light sensor, respectively. LOV1 of both phot1 and phot2 forms a dimer. However, oligomeric structures of LOV2 differ between phot1 and phot2. Phot2-LOV2 exists as a monomer and showed light-induced changes in the molecular size. Phot1-LOV2, while, has multiple oligomeric forms, such as, monomer, dimer and tetramer that showed no light-induced alteration.
