Abstract
Phototropins (phot1 and phot2), as blue light (BL) receptors, mediate phototropism, chloroplast relocation and stomatal opening in Arabidopsis. We provide biochemical evidence for the binding of 14-3-3 protein to Arabidopsis phot1. Overlay assay using a recombinant 14-3-3 protein showed that the 14-3-3 protein bound to phot1 in etiolated seedlings, leaves, and guard cells within 1 min after the start of BL pulse. The half-saturating intensity of BL was 7.2 μmol m-2 s-1 (30 s). Interestingly, the 14-3-3 proein did not bind to phot2 in any fluence rate of BL. Furthermore, phot1 was co-precipitated with the 14-3-3 protein in the etiolated seedlings in response to BL, suggesting that the 14-3-3 protein binds to phot1 in vivo. These results indicate that the binding of 14-3-3 protein to phot1 is common to phot1-mediated responses. Overlay assay using recombinant phot1 revealed that binding site(s) localizes in the region between LOV1 and LOV2.
