Cryptochromes (CRYs) are widespread flavoproteins with homology to photolyases (PHRs), a class of blue-light-activated DNA repair enzymes. Unlike PHRs, both plant and animal CRYs have a C-terminal domain. This cryptochrome C-terminal (CCT) domain mediates interactions with other proteins, while the PHR-like domain converts light energy into a signal via reduction and radical formation of the flavin adenine dinucleotide cofactor. However, the mechanism by which the PHR-like domain regulates the CCT domain is not known. Here, we applied the pulsed-laser-induced transient grating method to detect conformational changes induced by blue-light excitation of full-length Arabidopsis thaliana cryptochrome 1 (AtCRY1). A significant reduction in the diffusion coefficient of AtCRY1 was observed upon photoexcitation, indicating that a large conformational change occurs in this monomeric protein. AtCRY1 containing a single mutation (W324F) that abolishes an intra-protein electron transfer cascade did not exhibit this conformational change. Moreover, the conformational change was much reduced in protein lacking the CCT domain. Thus, we conclude that the observed large conformational changes triggered by light excitation of the PHR-like domain result from C-terminal domain rearrangement. This interdomain modulation would be critical for CRYs’ ability to transduce a bluelight signal into altered protein–protein interactions for biological activity. Lastly, we demonstrate that the transient grating technique provides a powerful method for the direct observation and understanding of photoreceptor dynamics.

TLR4 is indispensable for LPS-induced bone resorption in vivo.

Topical application of LPS as an antigen induced periodontal destruction when the serum level of anti-LPS IgG was elevated in rats immunized with LPS. The presence of C1qB suggests that the formation of immune complexes is involved in this destruction.

In the present study, we showed that the formation of immune complex appears to be involved in the acute phase of periodontal destruction and that the biological activity of antigens is also important.

These findings demonstrate that green tea extract suppresses the onset of loss of attachment and alveolar bone resorption in a rat model of experimental periodontitis.