01859nas a2200241 4500008004500000020001400045245011000059210006900169260000800238300001400246490000800260520114300268653001501411100002101426700001501447700001601462700001301478700001901491700002201510700001601532700002001548856004901568 2020 Engldsh a0006-349500aEvidence of Intramolecular Structural Stabilization in Light Activated State of Orange Carotenoid Protein0 aEvidence of Intramolecular Structural Stabilization in Light Act cFeb a208A-208A0 v1183 a
Orange carotenoid protein (OCP) controls efficiency of the light harvesting antenna, the phycobilisome (PBS), in diverse cyanobacteria and prevents oxidative damage. It is the only known photoactive protein that uses a carotenoid, canthaxanthin, as its chromophore. The structure of OCP consists of two globular domains, connected by an unstructured loop, that forms a hydrophobic pocket for the carotenoid. In low light, canthaxanthin bound OCP is inactive and appears orange. Illumination by strong light results in an active state that interacts with the PBS to induce fluorescence quenching, a red appearance and conformational changes that include a 12Å shift by canthaxanthin into the N-terminal domain. Terahertz (THz) dynamical transition measurements and anisotropic terahertz microscopy are used to measure the intramolecular structural dynamics in the inactive and active states, which can be induced by photoexcitation or chaotropic salts. The measurements indicate that the active state has a decrease in structural flexibility, which may be related to enhanced interactions with the PBS.
10aBiophysics1 aMcKinney, J., A.1 aSharma, A.1 aCrossen, K.1 aDeng, Y.1 aGeorge, D., K.1 aLechno-Yossef, S.1 aKerfeld, C.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/25300443nas a2200157 4500008004100000245004800041210004000089490000800129100001500137700001900152700001600171700001700187700001600204700001600220856004900236 2020 eng d00aIs the Protein Dynamical Transition useful?0 aProtein Dynamical Transition useful0 v1181 aSharma, A.1 aGeorge, D., K.1 aCrossen, K.1 aMcKinney, J.1 aKerfeld, C.1 aMarkelz, A. uhttps://markelz.physics.buffalo.edu/node/282