5FCX

Structure of Anabaena (Nostoc) sp. PCC 7120 Red Carotenoid Protein binding canthaxanthin

Summary for 5FCX

• Entry DOI: 10.2210/pdb5fcx/pdb
• Related: 5fcy
• Descriptor: Red carotenoid protein (RCP), beta,beta-carotene-4,4'-dione (2 entities in total)
• Functional Keywords: carotenoid, photoprotection, cyanobacteria, cartenoid binding protein
• Biological source: Nostoc sp.
• Total number of polymer chains: 2
• Total formula weight: 39610.90

Authors

Sutter, M.,Leverenz, R.L.,Kerfeld, C.A. (deposition date: 2015-12-15, release date: 2016-07-27, Last modification date: 2023-09-27)

Primary citation

Melnicki, M.R.,Leverenz, R.L.,Sutter, M.,Lopez-Igual, R.,Wilson, A.,Pawlowski, E.G.,Perreau, F.,Kirilovsky, D.,Kerfeld, C.A.
Structure, Diversity, and Evolution of a New Family of Soluble Carotenoid-Binding Proteins in Cyanobacteria.
Mol Plant, 9:1379-1394, 2016

PubMed Abstract: Using a phylogenomic approach, we have identified and subclassified a new family of carotenoid-binding proteins. These proteins have sequence homology to the N-terminal domain (NTD) of the Orange Carotenoid Protein (OCP), and are referred to as Helical Carotenoid Proteins (HCPs). These proteins comprise at least nine distinct clades and are found in diverse organisms, frequently as multiple paralogs representing the distinct clades. These seem to be out-paralogs maintained from ancient duplications associated with subfunctionalization. All of the HCPs share conservation of the residues for carotenoid binding, and we confirm that carotenoid binding is a fundamental property of HCPs. We solved two crystal structures of the Nostoc sp. PCC 7120 HCP1 protein, each binding a different carotenoid, suggesting that the proteins flexibly bind a range of carotenoids. Based on a comprehensive phylogenetic analysis, we propose that one of the HCP subtypes is likely the evolutionary ancestor of the NTD of the OCP, which arose following a domain fusion event. However, we predict that the majority of HCPs have functions distinct from the NTD of the OCP. Our results demonstrate that the HCPs are a new family of functionally diverse carotenoid-binding proteins found among ecophysiologically diverse cyanobacteria.

PubMed: 27392608
DOI: 10.1016/j.molp.2016.06.009

Experimental method

X-RAY DIFFRACTION (3.206 Å)