Characterization of a water-soluble carotenoid protein from Synechocystis PCC6803
Abstract
Colored carotenoid proteins are usually embedded within various membranes or the outer cell wall but a few are water soluble. Three water soluble oxygenated carotenoid proteins have been found in cyanobacteria (Holt and Krogmann 1981, Diverse-Pierluissi and Krogmann 1989, Engle et al. 1991). However, this group of colored proteins which are usually masked by phycobilin protein and which may deposit their chromophore on the anionic exchange matrix. From Synechocystis PCC6803, an echinenone derivative containing orange protein, OCP, was purified, and the partially identified OCP gene segment matches slr1963 in S. PCC6803 whole genome map from Kazusa Institute, Japan. Although the spectral and chromatographic characteristics of the holoprotein and chromophore of OCP are similar to the orange 3$\sp\prime$ hydroxyechinenone protein (Holt and Krogmann 1981), OCP has an apoprotein mass of 34.7 kD which is at least 10 kD different from previous studies. According to deduced estimations peptide sequence and MS data, OCP carries 4 chromophores maximally, 80% less than the previous. The secondary structure prediction analysis indicates that OCP is a globular protein containing 8 $\alpha$ helices with more which no more than 20 residues and 3 short $\beta$ sheets less than 10 residues long. There is an ATP/GTP binding motif near the N-terminus. These features are different from all the other reported carotenoid carrying proteins that contain $\beta$ sheets barrel to house carotenoid. Perhaps, OCP may be an energy dependent or ATP/GTP regulated carrier that deliver photon-quenching carotenoids to the periphery of the cell.
Degree
Ph.D.
Advisors
Krogmann, Purdue University.
Subject Area
Molecular biology|Microbiology|Botany
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.