Light-Induced Conformational Changes in the Plant Cryptochrome Photolyase Homology Region Resolved by Selective...

Area of Science:

• Plant molecular biology
• Photoreceptor research
• Spectroscopy

Background:

• Plant cryptochromes are blue/UV-A light photoreceptors controlling vital processes like flowering and circadian rhythms.
• Light triggers flavin photoreduction in cryptochromes, but secondary structural changes in the photolyase homology region (PHR) remain understudied.
• Previous research focused on C-terminal extension changes, leaving the PHR's structural dynamics less understood.

Purpose of the Study:

• To investigate light-induced conformational changes in the photolyase homology region (PHR) of Chlamydomonas reinhardtii cryptochrome.
• To elucidate the role of the PHR in cryptochrome signaling pathways.
• To apply advanced spectroscopic techniques for detailed structural analysis.

Main Methods:

• Light-induced infrared difference spectroscopy was employed.
• Global 13C and 15N isotope labeling strategies were developed and utilized.
• UV/vis spectroscopy and mass spectrometry confirmed sample integrity and labeling efficiency.

Main Results:

• Prominent conformational changes within the PHR were detected upon blue light illumination.
• Isotope labeling enabled clear resolution of protein-derived difference bands.
• These changes were distinct from those observed in the C-terminal extension.

Conclusions:

• Blue light induces significant conformational changes in the PHR of Chlamydomonas reinhardtii cryptochrome.
• These PHR structural alterations, alongside C-terminal changes, likely mediate cryptochrome signaling.
• The findings provide new insights into the molecular mechanisms of plant photoreception.